XIV. COFFEE HOUSES OF OLD PHILADELPHIA…

XIV. COFFEE HOUSES OF OLD PHILADELPHIA

Ye Coffee House, Philadelphia's first coffee house, opened about 1700--The two London coffee houses--The City tavern, or Merchants coffee house--How these, and other celebrated resorts, dominated the social, political, and business life of the Quaker City in the eighteenth century

William Penn is generally credited with the introduction of coffee into the Quaker colony which he founded on the Delaware in 1682. He also brought to the "city of brotherly love" that other great drink of human brotherhood, tea. At first (1700), "like tea, coffee was only a drink for the well-to-do, except in sips."[93] As was the case in the other English colonies, coffee languished for a time while tea rose in favor, more especially in the home.

Following the stamp act of 1765, and the tea tax of 1767, the Pennsylvania Colony joined hands with the others in a general tea boycott; and coffee received the same impetus as elsewhere in the colonies that became the thirteen original states.

The coffee houses of early Philadelphia loom large in the history of the city and the republic. Picturesque in themselves, with their distinctive colonial architecture, their associations also were romantic. Many a civic, sociological, and industrial reform came into existence in the low-ceilinged, sanded-floor main rooms of the city's early coffee houses.

For many years, Ye coffee house, the two London coffee houses, and the City tavern (also known as the Merchants coffee house) each in its turn dominated the official and social life of Philadelphia. The earlier houses were the regular meeting places of Quaker municipal officers, ship captains, and merchants who came to transact public and private business. As the outbreak of the Revolution drew near, fiery colonials, many in Quaker garb, congregated there to argue against British oppression of the colonies. After the Revolution, the leading citizens resorted to the coffee house to dine and sup and to hold their social functions.

When the city was founded in 1682, coffee cost too much to admit of its being retailed to the general public at coffee houses. William Penn wrote in his Accounts that in 1683 coffee in the berry was sometimes procured in New York at a cost of eighteen shillings nine pence the pound, equal to about $4.68. He told also that meals were served in the ordinaries at six pence (equal to twelve cents), to wit: "We have seven ordinaries for the entertainment of strangers and for workmen that are not housekeepers, and a good meal is to be had there for six pence sterling." With green coffee costing $4.68 a pound, making the price of a cup about seventeen cents, it is not likely that coffee was on the menus of the ordinaries serving meals at twelve cents each. Ale was the common meal-time beverage.

There were four classes of public houses--inns, taverns, ordinaries, and coffee houses. The inn was a modest hotel that supplied lodgings, food, and drink, the beverages consisting mostly of ale, port, Jamaica rum, and Madeira wine. The tavern, though accommodating guests with bed and board, was more of a drinking place than a lodging house. The ordinary combined the characteristics of a restaurant and a boarding house. The coffee house was a pretentious tavern, dispensing, in most cases, intoxicating drinks as well as coffee.

Philadelphia's First Coffee House

The first house of public resort opened in Philadelphia bore the name of the Blue Anchor tavern, and was probably established in 1683 or 1684; colonial records do not state definitely. As its name indicates, this was a tavern. The first coffee house came into existence about the year 1700. Watson, in one place in his Annals of the city, says 1700, but in another 1702. The earlier date is thought to be correct, and is seemingly substantiated by the co-authors Scharf and Westcott in their History of the city, in which they say, "The first public house designated as a coffee house was built in Penn's time [1682-1701] by Samuel Carpenter, on the east side of Front Street, probably above Walnut Street. That it was the first of its kind--the only one in fact for some years--seems to be established beyond doubt. It was always referred to in old times as 'Ye Coffee House.'"

Carpenter owned also the Globe inn, which was separated from Ye coffee house by a public stairway running down from Front Street to Water Street, and, it is supposed, to Carpenter's Wharf. The exact location of the old house was recently established from the title to the original patentee, Samuel Carpenter, by a Philadelphia real-estate title-guarantee company, as being between Walnut and Chestnut Streets, and occupying six and a half feet of what is now No. 137 South Front Street and the whole of No. 139.

How long Ye coffee house endured is uncertain. It was last mentioned in colonial records in a real estate conveyance from Carpenter to Samuel Finney, dated April 26, 1703. In that document it is described as "That brick Messuage, or Tenement, called Ye Coffee House, in the possession of Henry Flower, and situate, lying and being upon or before the bank of the Delaware River, containing in length about thirty feet and in breadth about twenty-four."

The Henry Flower mentioned as the proprietor of Philadelphia's first coffee house, was postmaster of the province for a number of years, and it is believed that Ye coffee house also did duty as the post-office for a time. Benjamin Franklin's Pennsylvania Gazette, in an issue published in 1734, has this advertisement:

All persons who are indebted to Henry Flower, late postmaster of Pennsylvania, for Postage of Letters or otherwise, are desir'd to pay the same to him at the old Coffee House in Philadelphia.

Flower's advertisement would indicate that Ye coffee house, then venerable enough to be designated as old, was still in existence, and that Flower was to be found there. Franklin also seems to have been in the coffee business, for in several issues of the Gazette around the year 1740 he advertised: "Very good coffee sold by the Printer."

The First London Coffee House

Philadelphia's second coffee house bore the name of the London coffee house, which title was later used for the resort William Bradford opened in 1754. The first house of this name was built in 1702, but there seems to be some doubt about its location. Writing in the American Historical Register, Charles H. Browning says: "William Rodney came to Philadelphia with Penn in 1682, and resided in Kent County, where he died in 1708; he built the old London coffee house at Front and Market Streets in 1702." Another chronicler gives its location as "above Walnut Street, either on the east side of Water Street, or on Delaware Avenue, or, as the streets are very close together, it may have been on both. John Shewbert, its proprietor, was a parishioner of Christ Church, and his establishment was largely patronized by Church of England people." It was also the gathering place of the followers of Penn and the Proprietary party, while their opponents, the political cohorts of Colonel Quarry, frequented Ye coffee house.

The first London coffee house resembled a fashionable club house in its later years, suitable for the "genteel" entertainments of the well-to-do Philadelphians. Ye coffee house was more of a commercial or public exchange. Evidence of the gentility of the London is given by John William Wallace:

The appointments of the London Coffee House, if we may infer what they were from the will of Mrs. Shubert [Shewbert] dated November 27, 1751, were genteel. By that instrument she makes bequest of two silver quart tankards; a silver cup; a silver porringer; a silver pepper pot; two sets of silver castors; a silver soup spoon; a silver sauce spoon, and numerous silver tablespoons and tea spoons, with a silver tea-pot.

One of the many historic incidents connected with this old house was the visit there by William Penn's eldest son, John, in 1733, when he entertained the General Assembly of the province on one day and on the next feasted the City Corporation.

Roberts' Coffee House

Another house with some fame in the middle of the eighteenth century was Roberts' coffee house, which stood in Front Street near the first London house. Though its opening date is unknown, it is believed to have come into existence about 1740. In 1744 a British army officer recruiting troops for service in Jamaica advertised in the newspaper of the day that he could be seen at the Widow Roberts' coffee house. During the French and Indian War, when Philadelphia was in grave danger of attack by French and Spanish privateers, the citizens felt so great relief when the British ship Otter came to the rescue, that they proposed a public banquet in honor of the Otter's captain to be held at Roberts' coffee house. For some unrecorded reason the entertainment was not given; probably because the house was too small to accommodate all the citizens desiring to attend. Widow Roberts retired in 1754.

The James Coffee House

Contemporary with Roberts' coffee house was the resort run first by Widow James, and later by her son, James James. It was established in 1744, and occupied a large wooden building on the northwest corner of Front and Walnut Streets. It was patronized by Governor Thomas and many of his political followers, and its name frequently appeared in the news and advertising columns of the Pennsylvania Gazette.

The Second London Coffee House

Probably the most celebrated coffee house in Penn's city was the one established by William Bradford, printer of the Pennsylvania Journal. It was on the southwest corner of Second and Market Streets, and was named the London coffee house, the second house in Philadelphia to bear that title. The building had stood since 1702, when Charles Reed, later mayor of the city, put it up on land which he bought from Letitia Penn, daughter of William Penn, the founder. Bradford was the first to use the structure for coffee-house purposes, and he tells his reason for entering upon the business in his petition to the governor for a license: "Having been advised to keep a Coffee House for the benefit of merchants and traders, and as some people may at times be desirous to be furnished with other liquors besides coffee, your petitioner apprehends it is necessary to have the Governor's license." This would indicate that in that day coffee was drunk as a refreshment between meals, as were spirituous liquors for so many years before, and thereafter up to 1920.

Bradford's London coffee house seems to have been a joint-stock enterprise, for in his Journal of April 11, 1754, appeared this notice: "Subscribers to a public coffee house are invited to meet at the Courthouse on Friday, the 19th instant, at 3 o'clock, to choose trustees agreeably to the plan of subscription."

The building was a three-story wooden structure, with an attic that some historians count as the fourth story. There was a wooden awning one-story high extending out to cover the sidewalk before the coffee house. The entrance was on Market (then known as High) Street.

The London coffee house was "the pulsating heart of excitement, enterprise, and patriotism" of the early city. The most active citizens congregated there--merchants, shipmasters, travelers from other colonies and countries, crown and provincial officers. The governor and persons of equal note went there at certain hours "to sip their coffee from the hissing urn, and some of those stately visitors had their own stalls." It had also the character of a mercantile exchange--carriages, horses, foodstuffs, and the like being sold there at auction. It is further related that the early slave-holding Philadelphians sold negro men, women, and children at vendue, exhibiting the slaves on a platform set up in the street before the coffee house.

The resort was the barometer of public sentiment. It was in the street before this house that a newspaper published in Barbados, bearing a stamp in accordance with the provisions of the stamp act, was publicly burned in 1765, amid the cheers of bystanders. It was here that Captain Wise of the brig Minerva, from Pool, England, who brought news of the repeal of the act, was enthusiastically greeted by the crowd in May, 1766. Here, too, for several years the fishermen set up May poles.

Bradford gave up the coffee house when he joined the newly formed Revolutionary army as major, later becoming a colonel. When the British entered the city in September, 1777, the officers resorted to the London coffee house, which was much frequented by Tory sympathizers. After the British had evacuated the city, Colonel Bradford resumed proprietorship; but he found a change in the public's attitude toward the old resort, and thereafter its fortunes began to decline, probably hastened by the keen competition offered by the City tavern, which had been opened a few years before.

Bradford gave up the lease in 1780, transferring the property to John Pemberton, who leased it to Gifford Dally. Pemberton was a Friend, and his scruples about gambling and other sins are well exhibited in the terms of the lease in which said Dally "covenants and agrees and promises that he will exert his endeavors as a Christian to preserve decency and order in said house, and to discourage the profanation of the sacred name of God Almighty by cursing, swearing, etc., and that the house on the first day of the week shall always be kept closed from public use." It is further covenanted that "under a penalty of L100 he will not allow or suffer any person to use, or play at, or divert themselves with cards, dice, backgammon, or any other unlawful game."

It would seem from the terms of the lease that what Pemberton thought were ungodly things, were countenanced in other coffee houses of the day. Perhaps the regulations were too strict; for a few years later the house had passed into the hands of John Stokes, who used it as dwelling and a store.

City Tavern or Merchants Coffee House

The last of the celebrated coffee houses in Philadelphia was built in 1773 under the name of the City tavern, which later became known as the Merchants coffee house, possibly after the house of the same name that was then famous in New York. It stood in Second Street near Walnut Street, and in some respects was even more noted than Bradford's London coffee house, with which it had to compete in its early days.

The City tavern was patterned after the best London coffee houses; and when opened, it was looked upon as the finest and largest of its kind in America. It was three stories high, built of brick, and had several large club rooms, two of which were connected by a wide doorway that, when open, made a large dining room fifty feet long.

Daniel Smith was the first proprietor, and he opened it to the public early in 1774. Before the Revolution, Smith had a hard struggle trying to win patronage from Bradford's London coffee house, standing only a few blocks away. But during and after the war, the City tavern gradually took the lead, and for more than a quarter of a century was the principal gathering place of the city. At first, the house had various names in the public mind, some calling it by its proper title, the City tavern, others attaching the name of the proprietor and designating it as Smith's tavern, while still others used the title, the New tavern.

The gentlefolk of the city resorted to the City tavern after the Revolution as they had to Bradford's coffee house before. However, before reaching this high estate, it once was near destruction at the hands of the Tories, who threatened to tear it down. That was when it was proposed to hold a banquet there in honor of Mrs. George Washington, who had stopped in the city in 1776 while on the way to meet her distinguished husband, then at Cambridge in Massachusetts, taking over command of the American army. Trouble was averted by Mrs. Washington tactfully declining to appear at the tavern.

After peace came, the house was the scene of many of the fashionable entertainments of the period. Here met the City Dancing Assembly, and here was held the brilliant fete given by M. Gerard, first accredited representative from France to the United States, in honor of Louis XVI's birthday. Washington, Jefferson, Hamilton, and other leaders of public thought were more or less frequent visitors when in Philadelphia.

The exact date when the City tavern became the Merchants coffee house is unknown. When James Kitchen became proprietor, at the beginning of the nineteenth century, it was so called. In 1806 Kitchen turned the house into a bourse, or mercantile exchange. By that time clubs and hotels had come into fashion, and the coffee-house idea was losing caste with the elite of the city.

In the year 1806 William Renshaw planned to open the Exchange coffee house in the Bingham mansion on Third Street. He even solicited subscriptions to the enterprise, saying that he proposed to keep a marine diary and a registry of vessels for sale, to receive and to forward ships' letter bags, and to have accommodations for holding auctions. But he was persuaded from the idea, partly by the fact that the Merchants coffee house seemed to be satisfactorily filling that particular niche in the city life, and partly because the hotel business offered better inducements. He abandoned the plan, and opened the Mansion House hotel in the Bingham residence in 1807.

XV. THE BOTANY OF THE COFFEE PLANT

Its complete classification by class, sub-class, order, family, genus, and species--How the Coffea arabica grows, flowers, and bears--Other species and hybrids described--Natural caffein-free coffee--Fungoid diseases of coffee

The coffee tree, scientifically known as Coffea arabica, is native to Abyssinia and Ethiopia, but grows well in Java, Sumatra, and other islands of the Dutch East Indies; in India, Arabia, equatorial Africa, the islands of the Pacific, in Mexico, Central and South America, and the West Indies. The plant belongs to the large sub-kingdom of plants known scientifically as the Angiosperms, or Angiospermae, which means that the plant reproduces by seeds which are enclosed in a box-like compartment, known as the ovary, at the base of the flower. The word Angiosperm is derived from two Greek words, sperma, a seed, and aggeion, pronounced angeion, a box, the box referred to being the ovary.

This large sub-kingdom is subdivided into two classes. The basis for this division is the number of leaves in the little plant which develops from the seed. The coffee plant, as it develops from the seed, has two little leaves, and therefore belongs to the class Dicotyledoneae. This word dicotyledoneae is made up of the two Greek words, di(s), two, and kotyledon, cavity or socket. It is not necessary to see the young plant that develops from the seed in order to know that it had two seed leaves; because the mature plant always shows certain characteristics that accompany this condition of the seed.

In every plant having two seed leaves, the mature leaves are netted-veined, which is a condition easily recognized even by the layman; also the parts of the flowers are in circles containing two or five parts, but never in threes or sixes. The stems of plants of this class always increase in thickness by means of a layer of cells known as a cambium, which is a tissue that continues to divide throughout its whole existence. The fact that this cambium divides as long as it lives, gives rise to a peculiar appearance in woody stems by which we can, on looking at the stem of a tree of this type when it has been sawed across, tell the age of the tree.

In the spring the cambium produces large open cells through which large quantities of sap can run; in the fall it produces very thick-walled cells, as there is not so much sap to be carried. Because these thin-walled open cells of one spring are next to the thick-walled cells of the last autumn, it is very easy to distinguish one year's growth from the next; the marks so produced are called annual rings.

We have now classified coffee as far as the class; and so far we could go if we had only the leaves and stem of the coffee plant. In order to proceed farther, we must have the flowers of the plant, as botanical classification goes from this point on the basis of the flowers. The class Dicotyledoneae is separated into sub-classes according to whether the flower's corolla (the showy part of the flower which ordinarily gives it its color) is all in one piece, or is divided into a number of parts. The coffee flower is arranged with its corolla all in one piece, forming a tube-shaped arrangement, and accordingly the coffee plant belongs to the sub-class Sympetalae, or Metachlamydeae, which means that its petals are united.

The next step in classification is to place the plant in the proper division under the sub-class, which is the order. Plants are separated into orders according to their varied characteristics. The coffee plant belongs to an order known as Rubiales. These orders are again divided into families. Coffee is placed in the family Rubiaceae, or Madder Family, in which we find herbs, shrubs or trees, represented by a few American plants, such as bluets, or Quaker ladies, small blue spring flowers, common to open meadows in northern United States; and partridge berries (Mitchella repens).

The Madder Family has more foreign representatives than native genera, among which are Coffea, Cinchona, and Ipecacuanha (Uragoga), all of which are of economic importance. The members of this family are noted for their action on the nervous system. Coffee, as is well known, contains an active principle known as caffein which acts as a stimulant to the nervous system and in small quantities is very beneficial. Cinchona supplies us with quinine, while Ipecacuanha produces ipecac, which is an emetic and purgative.

The families are divided into smaller sections known as genera, and to the genus Coffea belongs the coffee plant. Under this genus Coffea are several sub-genera, and to the sub-genus Eucoffea belongs our common coffee, Coffea arabica. Coffea arabica is the original or common Java coffee of commerce. The term "common" coffee may seem unnecessary, but there are many other species of coffee besides arabica. These species have not been described very frequently; because their native haunts are the tropics, and the tropics do not always offer favorable conditions for the study of their plants.

All botanists do not agree in their classification of the species and varieties of the coffea genus. M.E. de Wildman, curator of the royal botanical gardens at Brussels, in his Les Plantes Tropicales de Grande Culture, says the systematic division of this interesting genus is far from finished; in fact, it may be said hardly to be begun.

Coffea arabica we know best because of the important role it plays in commerce.

COMPLETE CLASSIFICATION OF COFFEE

Kingdom Vegetable Sub-Kingdom Angiospermae Class Dicotyledoneae Sub-class Sympetalae or Metachlamydeae Order Rubiales Family Rubiaceae Genus Coffea Sub-genus Eucoffea Species C. arabica

The coffee plant most cultivated for its berries is, as already stated, Coffea arabica, which is found in tropical regions, although it can grow in temperate climates. Unlike most plants that grow best in the tropics, it can stand low temperatures. It requires shade when it grows in hot, low-lying districts; but when it grows on elevated land, it thrives without such protection. Freeman[94] says there are about eight recognized species of coffea.

Coffea Arabica

Coffea arabica is a shrub with evergreen leaves, and reaches a height of fourteen to twenty feet when fully grown. The shrub produces dimorphic branches, i.e., branches of two forms, known as uprights and laterals. When young, the plants have a main stem, the upright, which, however, eventually sends out side shoots, the laterals. The laterals may send out other laterals, known as secondary laterals; but no lateral can ever produce an upright. The laterals are produced in pairs and are opposite, the pairs being borne in whorls around the stem. The laterals are produced only while the joint of the upright, to which they are attached, is young; and if they are broken off at that point, the upright has no power to reproduce them. The upright can produce new uprights also; but if an upright is cut off, the laterals at that position tend to thicken up. This is very desirable, as the laterals produce the flowers, which seldom appear on the uprights. This fact is utilized in pruning the coffee tree, the uprights being cut back, the laterals then becoming more productive. Planters generally keep their trees pruned down to about six feet.

The leaves are lanceolate, or lance-shaped, being borne in pairs opposite each other. They are three to six inches in length, with an acuminate apex, somewhat attenuate at the base, with very short petioles which are united with the short interpetiolar stipules at the base. The coffee leaves are thin, but of firm texture, slightly coriaceous. They are very dark green on the upper surface, but much lighter underneath. The margin of the leaf is entire and wavy. In some tropical countries the natives brew a coffee tea from the leaves of the coffee tree.

The coffee flowers are small, white, and very fragrant, having a delicate characteristic odor. They are borne in the axils of the leaves in clusters, and several crops are produced in one season, depending on the conditions of heat and moisture that prevail in the particular season. The different blossomings are classed as main blossoming and smaller blossomings. In semi-dry high districts, as in Costa Rica or Guatemala, there is one blossoming season, about March, and flowers and fruit are not found together, as a rule, on the trees. But in lowland plantations where rain is perennial, blooming and fruiting continue practically all the year; and ripe fruits, green fruits, open flowers, and flower buds are to be found at the same time on the same branchlet, not mixed together, but in the order indicated.

The flowers are also tubular, the tube of the corolla dividing into five white segments. Dr. P.J.S. Cramer, chief of the division of plant breeding, Department of Agriculture, Netherlands India, says the number of petals is not at all constant, not even for flowers of the same tree. The corolla segments are about one-half inch in length, while the tube itself is about three-eighths of an inch long. The anthers of the stamens, which are five in number, protrude from the top of the corolla tube, together with the top of the two-cleft pistil. The calyx, which is so small as to escape notice unless one is aware of its existence, is annular, with small, tooth-like indentations.

While the usual color of the coffee flower is white, the fresh stamens and pistils may have a greenish tinge, and in some cultivated species the corolla is pale pink.

The size and condition of the flowers are entirely dependent on the weather. The flowers are sometimes very small, very fragrant, and very numerous; while at other times, when the weather is not hot and dry, they are very large, but not so numerous. Both sets of flowers mentioned above "set fruit," as it is called; but at times, especially in a very dry season, they bear flowers that are few in number, small, and imperfectly formed, the petals frequently being green instead of white. These flowers do not set fruit. The flowers that open on a dry sunny day show a greater yield of fruit than those that open on a wet day, as the first mentioned have a better chance of being pollinated by the insects and the wind. The beauty of a coffee estate in flower is of a very fleeting character. One day it is a snowy expanse of fragrant white blossoms for miles and miles, as far as the eye can see, and two days later it reminds one of the lines from Villon's Des Dames du Temps Jadis.

Where are the snows of yesterday? The winter winds have blown them all away.

But here, the winter winds are not to blame: the soft, gentle breezes of the perpetual summer have wrought the havoc, leaving, however, a not unpleasing picture of dark, cool, mossy green foliage.

The flowers are beautiful, but the eye of the planter sees in them not alone beauty and fragrance. He looks far beyond, and in his mind's eye he sees bags and bags of green coffee, representing to him the goal and reward of all his toil. After the flowers droop, there appear what are commercially known as the coffee berries. Botanically speaking, "berry" is a misnomer. These little fruits are not berries, such as are well represented by the grape; but are drupes, which are better exemplified by the cherry and the peach. In the course of six or seven months, these coffee drupes develop into little red balls about the size of an ordinary cherry; but, instead of being round, they are somewhat ellipsoidal, having at the outer end a small umbilicus. The drupe of the coffee usually has two locules, each containing a little "stone" (the seed and its parchment covering) from which the coffee bean (seed) is obtained. Some few drupes contain three, while others, at the outer ends of the branches, contain only one round bean, known as the peaberry. The number of pickings corresponds to the different blossomings in the same season; and one tree of the species arabica may yield from one to twelve pounds a year.

In countries like India and Africa, the birds and monkeys eat the ripe coffee berries. The so-called "monkey coffee" of India, according to Arnold, is the undigested coffee beans passed through the alimentary canal of the animal.

The pulp surrounding the coffee beans is at present of no commercial importance. Although efforts have been made at various times by natives to use it as a food, its flavor has not gained any great popularity, and the birds are permitted a monopoly of the pulp as a food. From the human standpoint the pulp, or sarcocarp, as it is scientifically called, is rather an annoyance, as it must be removed in order to procure the beans. This is done in one of two ways. The first is known as the dry method, in which the entire fruit is allowed to dry, and is then cracked open. The second way is called the wet method; the sarcocarp is removed by machine, and two wet, slimy seed packets are obtained. These packets, which look for all the world like seeds, are allowed to dry in such a way that fermentation takes place. This rids them of all the slime; and, after they are thoroughly dry, the endocarp, the so-called parchment covering, is easily cracked open and removed. At the same time that the parchment is removed, a thin silvery membrane, the silver skin, beneath the parchment, comes off, too. There are always small fragments of this silver skin to be found in the groove of the coffee bean contained within the parchment packet.

We have said that the coffee tree yields from one to twelve pounds a year, but of course this varies with the individual tree and also with the region. In some countries the whole year's yield is less than 200 pounds per acre, while there is on record a patch in Brazil which yields about seventeen pounds to the tree, bringing the yield per acre much higher.

The beans do not retain their vitality for planting for any considerable length of time; and, if they are thoroughly dried, or are kept for longer than three or four months, they are useless for that purpose. It takes the seed about six weeks to germinate and to appear above ground. Trees raised from seed begin to blossom in about three years; but a good crop can not be expected of them for the first five or six years. Their usefulness, save in exceptional cases, is ended in about thirty years.

The coffee tree can be propagated in a way other than by seeds. The upright branches can be used as slips, which, after taking root, will produce seed-bearing laterals. The laterals themselves can not be used as slips. In Central America the natives sometimes use coffee uprights for fences and it is no uncommon sight to see the fence posts "growing."

The wood of the coffee tree is used also for cabinet work, as it is much stronger than many of the native woods, weighing about forty-three pounds to the cubic foot, having a crushing strength of 5,800 pounds per square inch, and a breaking strength of 10,900 pounds per square inch.

The propagation of the coffee plant by cutting has two distinct advantages over propagation by seed, in that it spares the expense of seed production, which is enormous, and it gives also a method of hybridization, which, if used, might lead not only to very interesting but also to very profitable results.

The hybridization of the coffee plant was taken up in a thoroughly scientific manner by the Dutch government at the experimental garden established at Bangelan, Java, in 1900. In his studies, twelve varieties of Coffea arabica are recognized by Dr. P.J.S. Cramer[95], namely:

Laurina, a hybrid of Coffea arabica with C. mauritiana, having small narrow leaves, stiff, dense branches, young leaves almost white, berry long and narrow, and beans narrow and oblong.

Murta, having small leaves, dense branches, beans as in the typical Coffea arabica, and the plant able to stand bitter cold.

Menosperma, a distinct type, with narrow leaves and bent-down branches resembling a willow, the berries seldom containing more than one seed.

Mokka (Coffea Mokkae), having small leaves, dense foliage, small round berries, small round beans resembling split peas, and possessed of a stronger flavor than Coffea arabica.

Purpurescens, a red-leaved variety, comparable with the red-leaved hazel and copper beech, a little less productive than the Coffea arabica.

Variegata, having variegated leaves striped and spotted with white.

Amarella, having yellow berries, comparable with the white-fruited variety of the strawberry, raspberry, etc.

Bullata, having broad, curled leaves; stiff, thick, fragile branches, and round, fleshy berries containing a high percentage of empty beans.

Angustifolia, a narrow-leaved variety, with berries somewhat more oblong and, like the foregoing, a poor producer.

Erecta, a variety that is sturdier than the typical arabica, better suited to windy places, and having a production as in the common arabica.

Maragogipe, a well-defined variety with light green leaves having colored edges: berries large, broad, sometimes narrower in the middle; a light bearer, the whole crop sometimes being reduced to a couple of berries per tree.[96]

Columnaris, a vigorous variety, sometimes reaching a height of 25 feet, having leaves rounded at the base and rather broad, but a shy bearer, recommended for dry climates.

Coffea Stenophylla

Coffea arabica has a formidable rival in the species stenophylla. The flavor of this variety is pronounced by some as surpassing that of arabica. The great disadvantage of this plant is the fact that it requires so long a time before a yield of any value can be secured. Although the time required for the maturing of the crop is so long, when once the plantation begins to yield, the crop is as large as that of Coffea arabica, and occasionally somewhat larger. The leaves are smaller than any of the species described, and the flowers bear their parts in numbers varying from six to nine. The tree is a native of Sierra Leone, where it grows wild.

Coffea Liberica

The bean of Coffea arabica, although the principal bean used in commerce, is not the only one; and it may not be out of place here to describe briefly some of the other varieties that are produced commercially. Coffea liberica is one of these plants. The quality of the beverage made from its berries is inferior to that of Coffea arabica, but the plant itself offers distinct advantages in its hardy growing qualities. This makes it attractive for hybridization.

The Coffea liberica tree is much larger and sturdier than the Coffea arabica, and in its native haunts it reaches a height of 30 feet. It will grow in a much more torrid climate and can stand exposure to strong sunlight. The leaves are about twice as long as those of arabica, being six to twelve inches in length, and are very thick, tough, and leathery. The apex of the leaf is acute. The flowers are larger than those of arabica, and are borne in dense clusters. At any time during the season, the same tree may bear flowers, white or pinkish, and fragrant, or even green, together with fruits, some green, some ripe and of a brilliant red. The corolla has been known to have seven segments, though as a rule it has five. The fruits are large, round, and dull red; the pulps are not juicy, and are somewhat bitter. Unlike Coffea arabica, the ripened drupes do not fall from the trees, and so the picking can be delayed at the planter's convenience.

Among the allied Liberian species Dr. Cramer recognizes:

Abeokutae, having small leaves of a bright green, flower buds often pink just before opening (in Liberian coffee never), fruit smaller with sharply striped red and yellow shiny skin, and producing somewhat smaller beans than Liberian coffee, but beans whose flavor and taste are praised by brokers;

Dewevrei, having curled edged leaves, stiff branches, thick-skinned berries, sometimes pink flowers, beans generally smaller than in C. liberica, but of little interest to the trade;

Arnoldiana, a species near to Coffea Abeokutae having darker foliage and the even colored small berries;

Laurentii Gillet, a species not to be confused with the C. Laurentii belonging to the robusta coffee, but standing near to C. liberica, characterized by oblong rather than thin-skinned berries;

Excelsa, a vigorous, disease-resisting species discovered in 1905 by Aug. Chevalier in West Africa, in the region of the Chari River, not far from Lake Tchad. The broad, dark-green leaves have an under side of light green with a bluish tinge; the flowers are large and white, borne in axillary clusters of one to five; the berries are short and broad, in color crimson, the bean smaller than robusta, very like Mocha, but in color a bright yellow like liberica. The caffein content of the coffee is high, and the aroma is very pronounced;

Dybowskii, another disease-resisting variety similar to excelsa, but having different leaf and fruit characteristics;

Lamboray, having bent gutter-like leaves, and soft-skinned, oblong fruit;

Wanni Rukula, having large leaves, a vigorous growth, and small berries;

Coffea aruwimensis, being a mixture of different types.

The last three types were received by Dr. Cramer at Bangelan from Frere Gillet in the Belgian Congo, and were still under trial in Java in 1919.

Coffea Robusta

Emil Laurent, in 1898, discovered a species of coffee growing wild in Congo. This was taken up by a horticultural firm of Brussels, and cultivated for the market. This firm gave to the coffee the name Coffea robusta, although it had already been given the name of the discoverer, being known as Coffea Laurentii. The plant differs widely from both arabica and liberica, being considerably larger than either. The tree is umbrella-shaped, due to the fact that its branches are very long and bend toward the ground.

The leaves of robusta are much thinner than those of liberica, though not as thin as those of arabica. The tree, as a whole, is a very hardy variety and even bears blossoms when it is less than a year old. It blossoms throughout the entire year, the flowers having six-parted corollas. The drupes are smaller than those of liberica; but are much thinner skinned, so that the coffee bean is actually not any smaller. The drupes mature in ten months. Although the plants bear as early as the first year, the yield for the first two years is of no account; but by the fourth year the crop is large.

Arno Viehoever, pharmacognosist in charge of the pharmacognosy laboratory of the Bureau of Chemistry, United States Department of Agriculture, has recently announced findings confirming Hartwich which appear to permit of differentiation between robusta, arabica, and liberica.[97] These are mainly the peculiar folding of the endosperm, showing quite generally a distinct hook in the case of the robusta coffee bean. The size of the embryo, and especially the relation of the rootlet to hypercotyl, will be found useful in the differentiation of the species Coffea arabica, liberica, and robusta (see cut, page 142).

Viehoever and Lepper carried on a series of cup tests of robusta, the results as to taste and flavor being distinctly favorable. They summarized their studies and tests as follows:

The time when coffee could be limited to beans obtained from plants of Coffea arabica and Coffea liberica has passed. Other species, with qualities which make them desirable, even in preference to the well reputed named ones, have been discovered and cultivated. Among them, the species or group of Coffea robusta has attained a great economic significance, and is grown in increasing amounts. While it has, as reports seem to indicate, not as yet been possible to obtain a strain that would be as desirable in flavor as the old "standard" Coffea arabica, well known as Java or "Fancy Java" coffee, its merits have been established.

The botanical origin is not quite cleared up, and the classification of the varieties belonging to the robusta group deserves further study. Anatomical means of differentiating robusta coffee from other species or groups, may be applied as distinctly helpful....

As is usual in most of the coffee species, caffein is present. The amount appears to be, on an average, somewhat larger (even exceeding 2.0 percent) than in the South American coffee species. In no instance, however, did the amount exceed the maximum limits observed in coffee in general....

Due to its rapid growth, early and prolific yield, resistance to coffee blight, and many other desirable qualities, Coffea robusta has established "its own". In the writers' judgment, robusta coffee deserves consideration and recognition.

Among the robusta varieties, Coffea canephora is a distinct species, well characterized by growth, leaves, and berries. The branches are slender and thinner than robusta; the leaves are dark green and narrower; the flowers are often tinged with red; the unripe berries are purple, the ripe berries bright red and oblong. The produce is like robusta, only the shape of the bean, somewhat narrower and more oblong, makes it look more attractive. Coffea canephora, like C. robusta, seems better fitted to higher altitudes.

Other canephora varieties include:

Madagascar, having small, slightly striped, bright red berries and small round beans;

Quillouensis, having dark green foliage and reddish brown young leaves; and,

Stenophylla Paris, with purplish young berries.

These last two named were under test at the Bangelan gardens in 1919.

Among other allied robusta species are:

Ugandae:, whose produce is said to possess a better flavor than robusta;

Bukobensis, different from Ugandae in the color of its berries, which are a dark red; and

Quillou, having bright red fruit, a copper-colored silver skin, three pounds of fruit producing one pound of market coffee. Some people prefer Quillou to robusta because of the difference in the taste of the roasted bean.

Some Interesting Hybrids

The most popular hybrid belongs to a crossing of liberica and arabica. Cramer states that the beans of this hybrid make an excellent coffee combining the strong taste of the liberica with the fine flavor of the old Government Java (arabica), adding:

The hybrids are not only of value to the roaster, but also to the planter. They are vigorous trees, practically free from leaf disease; they stand drought well and also heavy rains; they are not particular in regard to shade and upkeep; never fail to give a fair and often a rather heavy crop. The fruit ripens all the year around, and does not fall so easily as in the case of arabica.

Among other hybrids (many were still under trial in 1919) may be mentioned: Coffea excelsia x liberica; C. Abeokutae x liberica; C. Dybowskii x excelsa; C. stenophylla x Abeokutae; C. congensis x Ugandae; C. Ugandae x congensis; and C. robusta x Maragogipe.

There are many species of Coffea that stand quite apart from the main groups, arabica, robusta and liberica; but while some are of commercial value, most of them are interesting only from the scientific point of view. Among the latter may be mentioned: Coffea bengalensis, C. Perieri, C. mauritiana, C. macrocarpa, C. madagascariensis, and C. schumanniana.

M. Teyssonnier, of the experimental garden at Camayenne, French Guinea, West Africa, has produced a promising species of coffee known as affinis. It is a hybrid of C. stenophylla with a species of liberica.

Among other promising species recognized by Dr. Cramer are:

Coffea congensis, whose berry resembles that of C. arabica, when well prepared for the market being green or bluish; and

Coffea congensis var. Chalotii, probably a hybrid of C. congensis with C. canephora.

Caffein-free Coffee

Certain trees growing wild in the Comoro Islands and Madagascar are known as caffein-free coffee trees. Just whether they are entitled to this classification or not is a question. Some of the French and German investigators have reported coffee from these regions that was absolutely devoid of caffein. It was thought at first that they must represent an entirely new genus; but upon investigation, it was found that they belonged to the genus Coffea, to which all our common coffees belong. Professor Dubard, of the French National Museum and Colonial Garden, studied these trees botanically and classified them as C. Gallienii, C. Bonnieri, C. Mogeneti, and C. Augagneuri. The beans of berries from these trees were analyzed by Professor Bertrand and pronounced caffein-free; but Labroy, in writing of the same coffee, states that, while the bean is caffein-free, it contains a very bitter substance, cafamarine, which makes the infusion unfit for use. Dr. O.W. Willcox[98], in examining some specimens of wild coffee from Madagascar, found that the bean was not caffein-free; and though the caffein content was low, it was no lower than in some of the Porto Rican varieties.

Hartwich[99] reports that Hanausek found no caffein in C. mauritiana, C. humboltiana, C. Gallienii, C. Bonnerii, and C. Mogeneti.

Fungoid Disease of Coffee

The coffee tree, like every other living thing, has specific diseases and enemies, the most common of which are certain fungoid diseases where the mycelium of the fungus grows into the tissue and spots the leaves, eventually causing them to fall, thus robbing the plant of its only means of elaborating food. Its most deadly enemy in the insect world is a small insect of the lepidopterous variety, which is known as the coffee-leaf miner. It is closely related to the clothes moth and, like the moth, bores in its larval stage, feeding on the mesophyl of the leaves. This gives the leaves an appearance of being shriveled or dried by heat.

There are three principal diseases, due to fungi, from which the coffee plants suffer. The most common is known as the leaf-blight fungus, Pellicularia tokeroga, which is a slow-spreading disease, but one that causes great loss. Although the fungus does not produce spores, the leaves die and dry, and are blown away, carrying with them the dried mycelium of the fungus. This mycelium will start to grow as soon as it is supplied with a new moist coffee leaf to nourish it. The method of getting rid of this disease is to spray the trees in seasons of drought.

It was a fungoid disease known as the Hemileia vastatrix that attacked Ceylon's coffee industry in 1869, and eventually destroyed it. It is a microscopic fungus whose spores, carried by the wind, adhere to and germinate upon the leaves of the coffee tree[100].

Another common disease is known as the root disease, which eventually kills the tree by girdling it below the soil. It spreads slowly, but seems to be favored by collections of decaying matter around the base of the tree. Sometimes the digging of ditches around the roots is sufficient to protect it. The other common disease is due to Stilbium flavidum, and is found only in regions of great humidity. It affects both the leaf and the fruit and is known as the spot of leaf and fruit.

XVI. THE MICROSCOPY OF THE COFFEE FRUIT

How the beans may be examined under the microscope, and what is revealed--Structure of the berry, the green, and the roasted bean--The coffee leaf disease under the microscope--Value of microscopic analysis in detecting adulteration

The microscopy of coffee is, on the whole, more important to the planter than to the consumer and the dealer; while, on the other hand, the microscopy is of paramount importance to the consumer and the dealer as furnishing the best means of determining whether the product offered is adulterated or not. Also, from this standpoint, the microscopy of the plant is less important than that of the bean.

The Fruit and the Bean

The fruit, as stated in chapter XV, consists of two parts, each one containing a single seed, or bean. These beans are flattened laterally, so as to fit together, except in the following instances: in the peaberry, where one of the ovules never develops, the single ovule, having no pressure upon it, is spherical; in the rare instances where three seeds are found, the grains are angular.

The coffee bean with which the consumer is familiar is only a small part of the fruit. The fruit, which is the size of a small cherry, has, like the cherry, an outer fleshy portion called the pericarp. Beneath this is a part like tissue paper, spoken of technically as the parchment, but known scientifically as the endocarp. Next in position to this, and covering the seed, is the so-called spermoderm, which means the seed skin, referred to in the trade as the silver skin. Small portions of this silver skin are always to be found in the cleft of the coffee bean.

The coffee bean is the embryo and its food supply; the embryo is that part of the seed which, when supplied with food and moisture, develops into a new plant. The embryo of the coffee is very minute (Fig. 331, II, Em)[101]; and the greater part of the seed is taken up by the food supply, consisting of hard and soft endosperm (Fig. 331, I and II, Sa, Sp). The minute embryo consists of two small thick leaves, the cotyledons (Fig. 331, III, cot), a short stem, invisible in the undissected embryo, and a small root, the radicle (Fig. 331, III, rad).

Fruit Structure

In order to examine the structure of these layers of the fruit under the microscope, it is necessary to use the pericarp dry, as it is not easily obtainable in its natural condition. If desired, an alcoholic specimen may be used, but it has been found that the dry method gives more satisfactory results. The dried pericarp is about 0.5 mm thick. Great difficulty is experienced in cutting microtome sections of pericarp when the specimen is embedded in paraffin, because the outer layers are soft and the endocarp is hard, and the two parts of the section separate at this point. To overcome this, the sections might also be embedded in celloidin. When the sections are satisfactory, they may be stained with any of the double stains ordinarily used in the study of plant histology.

A section cut crosswise through the entire fruit would present the appearance shown in Fig. 333. The cells of the epicarp are broad and polygonal, sometimes regularly four-sided, about 15-35 mu broad. At intervals along the surface of the epicarp are stomata, or breathing pores, surrounded by guard cells. The next layer of the pericarp is the mesocarp (Figs. 333, 334, 335), the cells of which are larger and more regular in outline than the epicarp. The cells of the mesocarp become as large as 100 mu broad, but in the inner parts of the layer they become very much flattened. Fibrovascular bundles are scattered through the compressed cells of the mesocarp. The cell walls are thick; and large, amorphous, brown masses are found within the cell; occasionally, large crystals are found in the outer part of the layer. The fibro-vascular bundles consist mainly of bast and wood fibers and vessels. The bast fibers are as large as 1 mm long and 25 mu broad, with thick walls and very small lumina. Spiral and pitted vessels are also present.

The layer next to this is a soft tissue, parenchyma (Fig. 333, 5; Fig. 334, p). The parenchyma, or palisade cells as they are called, is a thin-walled tissue in which the cells are elongated, from which fact they receive their name. The walls of these cells, though very thin, are mucilaginous, and capable of taking up large amounts of water. They stain well with the aniline stains.

The endocarp (Fig. 336) is closely connected with the palisade layer and has thin-walled cells that closely resemble, in all respects, the endocarp of the apple. The outer layer consists of thick-walled fibers, which are remarkably porous (Fig. 333, 6; Fig. 336) while the fibers of the inner layer are thin-walled and run in the transverse direction.

The Bean Structure

Spermoderm, or silver skin, is not difficult to secure for microscopic analysis; because shreds of it remain in the groove of the berry, and these shreds are ample for examination. It can readily be removed without tearing, if soaked in water for a few hours. The spermoderm is thin enough not to need sectioning. It consists of two elements--sclerenchyma and parenchyma cells. (Figs. 333, 337, st, p).

Sclerenchyma forms an uninterrupted covering in the early stages of the seed; but as the seed develops, surrounding tissues grow more rapidly than the sclerenchyma, and the cells are pushed apart and scattered. The cells occurring in the cleft of the berry are straight, narrow, and long, becoming as long as 1 mm, and resemble bast fibers somewhat. On the surface of the berry, and sometimes in the cleft, there are found smaller, thicker cells, which are irregular in outline, club-shaped and vermiform types predominating.

Parenchyma cells form the remainder of the spermoderm; and these are partially obliterated, so that the structure is not easily seen, appearing almost like a solid membrane. The raphe runs through the parenchyma found in the cleft of the berry.

The endosperm (Figs. 333; 338) consist of small cells in the outer part, and large cells, frequently as thick as 100 mu, in the inner part. The cell walls are thickened and knotted. Certain of the inner cells have mucilaginous walls which when treated with water disappear, leaving only the middle lamellae, which gives the section a peculiar appearance. The cells contain no starch, the reserve food supply being stored cellulose, protein, and aleurone grains. Various investigators report the presence of sugar, tannin, iron, salts, and caffein.

The embryo (Fig. 331, III) may be obtained by soaking the bean in water for several hours, cutting through the cleft and carefully breaking apart the endosperm. If it is now soaked in diluted alkali, the embryo protrudes through the lower end of the endosperm. It is then cleared in alkali, or in chloral hydrate. The cotyledons shown have three pairs of veins, which are slightly netted. The radicle is blunt and is about 3/4 mm in length, while the cotyledons are 1/2 mm long.

The Coffee-Leaf Disease

The coffee tree has many pests and diseases; but the disease most feared by planters is that generally referred to as the coffee-leaf disease, and by this is meant the fungoid Hemileia vastatrix, which as told in chapter XV, destroyed Ceylon's once prosperous coffee industry. As it has since been found in nearly all coffee-producing countries, it has become a nightmare in the dreams of all coffee planters. The microscope shows how the spores of this dreaded fungus, carried by the winds upon a leaf of the coffee tree, proceed to germinate at the expense of the leaf; robbing it of its nourishment, and causing it to droop and to die. A mixture of powdered lime and sulphur has been found to be an effective germicide, if used in time and diligently applied.

Value of Microscopic Analysis

The value of the microscopic analysis of coffee may not be apparent at first sight; but when one realizes that in many cases the microscopic examination is the only way to detect adulteration in coffee, its importance at once becomes apparent. In many instances the chemical analysis fails to get at the root of the trouble, and then the only method to which the tester has recourse is the examination of the suspected material under the scope. The mixing of chicory with coffee has in the past been one of the commonest forms of adulteration. The microscopic examination in this connection is the most reliable. The coffee grain will have the appearance already described. Microscopically, chicory shows numerous thin-walled parenchymatous cells, lactiferous vessels, and sieve tubes with transverse plates. There are also present large vessels with huge, well-defined pits.

Roasted date stones have been used as adulterants, and these can be detected quite readily with the aid of the microscope, as they have a very characteristic microscopic appearance. The epidermal cells are almost oblong, while the parenchymatous cells are large, irregular and contain large quantities of tannin.

Adulteration and adulterants are considered more fully in chapter XVII.

XVII. THE CHEMISTRY OF THE COFFEE BEAN

Chemistry of the preparation and treatment of the green bean--Artificial aging--Renovating damaged coffees--Extracts--"Caffetannic acid"--Caffein, caffein-free coffee--Caffeol--Fats and oils--Carbohydrates--Roasting--Scientific aspects of grinding and packaging--The coffee brew--Soluble coffee--Adulterants and substitutes--Official methods of analysis

By Charles W. Trigg

Industrial Fellow of the Mellon Institute of Industrial Research, Pittsburgh, 1916-1920

When the vast extent of the coffee business is considered, together with the intimate connection which coffee has with the daily life of the average human, the relatively small amount of accurate knowledge which we possess regarding the chemical constituents and the physiological action of coffee is productive of amazement.

True, a painstaking compilation of all the scientific and semi-scientific work done upon coffee furnishes quite a compendium of data, the value of which is not commensurate with its quantity, because of the spasmodic nature of the investigations and the non-conclusive character of the results so far obtained. The following general survey of the field argues in favor of the promulgation of well-ordered and systematic research, of the type now in progress at several places in the United States, into the chemical behavior of coffee throughout the various processes to which it is subjected in the course of its preparation for human consumption.

Green Coffee

One of the few chemical investigations of the growing tree is the examination by Graf of flowers from 20-year-old coffee trees, in which he found 0.9 percent caffein, a reducing sugar, caffetannic acid, and phytosterol. Power and Chestnut[102] found 0.82 percent caffein in air-dried coffee leaves, but only 0.087 percent of the alkaloid in the stems of the plant separated from the leaves. In the course of a study[103] instituted for the purpose of determining the best fertilizers for coffee trees, it developed that the cherries in different stages of growth show a preponderance of potash throughout, while the proportion of P_2_O_5 attains a maximum in the fourth month and then steadily declines.

Experiments are still in progress to ascertain the precise mineral requirements of the crop as well as the most suitable stage at which to apply them. During the first five months the moisture content undergoes a steady decrease, from 87.13 percent to 65.77 percent, but during the final ripening stage in the last month there is a rise of nearly 1 percent. This may explain the premature falling and failure to ripen of the crop on certain soils, especially in years of low rainfall. Malnutrition of the trees may result also in the production of oily beans.[104]

The coffee berry comprises about 68 percent pulp, 6 percent parchment, and 26 percent clean coffee beans. The pulp is easily removed by mechanical means; but in order to separate the soft, glutinous, saccharine parchment, it is necessary to resort to fermentation, which loosens the skin so that it may be removed easily, after which the coffee is properly dried and aged. There is first a yeast fermentation producing alcohol; and then a bacterial action giving mainly inactive lactic acid, which is the main factor in loosening the parchment. For the production of the best coffee, acetic acid fermentation (which changes the color of the bean) and temperature above 60 deg. should be avoided, as these inhibit subsequent enzymatic action.[105]

Various schemes have been proposed for utilizing the large amount of pulp so obtained in preparing coffee for market. Most of these depend upon using the pulp as fertilizer, since fresh pulp contains 2.61 percent nitrogen, 0.81 percent P_2_O_5, 2.38 percent potassium, and 0.57 percent calcium. One procedure[106] in particular is to mix pulp with sawdust, urine, and a little lime, and then to leave this mixture covered in a pit for a year before using. In addition to these mineral matters, the pulp also contains about 0.88 percent of caffein and 18 to 37 percent sugars. Accordingly, it has been proposed[107] to extract the caffein with chloroform, and the sugars with acidulated water. The aqueous solution so obtained is then fermented to alcohol. The insoluble portion left after extraction can be used as fuel, and the resulting ash as fertilizer.

The pulp has been dried and roasted for use in place of the berry, and has been imported to England for this purpose. It is stated that the Arabs in the vicinity of Jiddah discard the kernel of the coffee berries and make an infusion of the husk.[108]

Quality of green coffee is largely dependent upon the methods used and the care taken in curing it, and upon the conditions obtaining in shipment and storage. True, the soil and climatic conditions play a determinative role in the creation of the characteristics of coffee, but these do not offer any greater opportunity for constructive research and remunerative improvement than does the development of methods and control in the processes employed in the preparation of green coffee for the market.

Storage prior and subsequent to shipment, and circumstances existing during transportation, are not to be disregarded as factors contributory to the final quality of the coffee. The sweating of mules carrying bags of poorly packed coffee, and the absorption of strong foreign aromas and flavors from odoriferous substances stored in too close proximity to the coffee beans, are classic examples of damage that bear iterative mention. Damage by sea water, due more to the excessive moisture than to the salt, is not so common an occurrence now as heretofore. However, a cheap and thoroughly effective means of ethically renovating coffee which has been damaged in this manner would not go begging for commercial application.

That green coffee improves with age, is a tenet generally accepted by the trade. Shipments long in transit, subjected to the effects of tropical heat under closely battened hatches in poorly ventilated holds, have developed into much-prized yellow matured coffee. Were it not for the large capital required and the attendant prohibitive carrying charges, many roasters would permit their coffees to age more thoroughly before roasting. In fact, some roasters do indulge this desire in regard to a portion of their stock. But were it feasible to treat and hold coffees long enough to develop their attributes to a maximum, still the exact conditions which would favor such development are not definitely known. What are the optimum temperature and the correct humidity to maintain, and should the green coffee be well ventilated or not while in storage? How long should coffee be stored under the most favorable conditions best to develop it? Aging for too long a period will develop flavor at the expense of body; and the general cup efficiency of some coffees will suffer if they be kept too long.

The exact reason for improvement upon aging is in no wise certain, but it is highly probable that the changes ensuing are somewhat analogous to those occurring in the aging of grain. Primarily an undefined enzymatic and mold action most likely occurs, the nature of the enzymes and molds being largely dependent upon the previous treatment of the coffee. Along with this are a loss of moisture and an oxidation, all three actions having more evident effects with the passage of time.

Artificial Aging

In consideration of the higher prices which aged products demand, attempts have naturally been made to shorten by artificial means the time necessary for their natural production. Some of these methods depend upon obtaining the most favorable conditions for acceleration of the enzyme action; others, upon the effects of micro-organisms; and still others, upon direct chemical reaction or physical alteration of the green bean.

One of the first efforts toward artificial maturing was that of Ashcroft[109], who argued from the improved nature of coffee which had experienced a delayed voyage. His method consisted of inclosing the coffee in sweat-boxes having perforated bottoms and subjecting it to the sweating action of steam, the boxes being enclosed in an oven or room maintained at the temperature of steam.

Timby[110] claimed to remove dusts, foreign odors, and impurities, while attaining in a few hours or days a ripening effect normally secured only in several seasons. In this process, the bagged coffee is placed in autoclaves and subjected to the action of air at a pressure of 2 to 3 atmospheres and a temperature of 40 deg. to 100 deg. F. The temperature should seldom be allowed to rise above 150 deg. F. The pressure is then allowed to escape and a partial vacuum created in the apparatus. This alteration of pressure and vacuum is continued until the desired maturation is obtained. Desvignes[111] employs a similar procedure, although he accomplishes seasoning by treating the coffee also with oxygen or ozone.[112] First the coffee is rendered porous by storage in a hot chamber, which is then exhausted prior to admission of the oxygen. The oxygen can be ozonized in the closed vessel while in contact with the coffee. Complete aging in a few days is claimed.

Weitzmann[113] adopts a novel operation, by exposing bags of raw coffee to the action of a powerful magnetic field, obtained with two adjustable electro-magnets. The claim that a maturation naturally produced in several years is thus obtained in 1/2 to 2 hours is open to considerable doubt. A process that is probably attended with more commercial success is that of Gram[114] in which the coffee is treated with gaseous nitrogen dioxid.

By far the most notable progress in this field, both scientifically and commercially, has been made by Robison[115] with his "culturing" method. Here the green coffee is washed with water, and then inoculated with selected strains of micro-organisms, such as Ochraeceus or Aspergillus Wintii. Incubation is then conducted for 6 to 7 days at 90 deg. F. and 85 percent relative humidity. Subsequent to this incubation, the coffee is stored in bins for about ten days; after which it is tumbled and scoured. With this process it is possible to improve the cupping qualities of a coffee to a surprising degree.

Renovating Damaged Coffees

Sophistication has often been resorted to in order ostensibly to improve damaged or cheap coffee. Glazing, coloring, and polishing of the green beans was openly and covertly practised until restricted by law. The steps employed did not actually improve the coffee by any means, but merely put it into condition for more ready sale. An apparently sincere endeavor to renovate damaged coffee was made by Evans[116] when he treated it with an aqueous solution of sulphuric acid having a density of 10.5 deg. Baume. After agitation in this solution, the beans were washed free from acid and dried. In this manner discolorations and impurities were removed and the beans given a fuller appearance.

The addition of glucose, sucrose, lactose, or dextrin to green coffees is practised by von Niessen[117] and by Winter[118], with the object of giving a mild taste and strong aroma to "hard" coffees. The addition is accomplished by impregnating, with or without the aid of vacuum, the beans with a moderately concentrated solution of the sugar, the liquid being of insufficient quantity to effect extraction. When the solution has completely disseminated through the kernels, they are removed and dried. Upon subsequent roasting, a decided amelioration of flavor is secured.

Another method developed by von Niessen[119] comprises the softening of the outer layers of the beans by steam, cold or warm water, or brine, and then surrounding them with an absorbent paste or powder, such as china clay, to which a neutralizing agent such as magnesium oxid may be added. After drying, the clay can be removed by brushing or by causing the beans to travel between oppositely reciprocated wet cloths. In the development of this process, von Niessen evidently argued that the so-called "caffetannic acid" is the "harmful" substance in coffee, and that it is concentrated in the outer layers of the coffee beans. If these be his precepts, the question of their correctness and of the efficiency of his process becomes a moot one.

A procedure which aims at cleaning and refining raw coffee, and which has been the subject of much polemical discussion, is that of Thum[120]. It entails the placing of the green beans in a perforated drum; just covering them with water, or a solution of sodium chloride or sodium carbonate, at 65 deg. to 70 deg. C.; and subjecting them to a vigorous brushing for from 1 to 5 minutes, according to the grade of coffee being treated. The value of this method is somewhat doubtful, as it would not seem to accomplish any more than simple washing. In fact, if anything, the process is undesirable; as some of the extractive matters present in the coffee, and particularly caffein, will be lost. Both Freund[121] and Harnack[122] hold briefs for the product produced by this method, and the latter endeavors analytically to prove its merits; but as his experimental data are questionable, his conclusions do not carry much weight.

The Acids of Coffee

The study of the acids of coffee has been productive of much controversy and many contradictory results, few of which possess any value. The acid of coffee is generally spoken of as "caffetannic acid." Quite a few attempts have been made to determine the composition and structure of this compound and to assign it a formula. Among them may be noted those of Allen,[123] who gives it the empirical formula C_14_H_16_O_7; Hlasiwetz,[124] who represents it as C_15_H_18_O_8; Richter, as C_30_H_18_O_16; Griebel,[125] as C_18_H_24_O_10, and Cazeneuve and Haddon,[126] as C_21_H_28_O_14. It is variously supposed to exist in coffee as the potassium, calcium, or magnesium salt. In regard to the physical appearance of the isolated substance there is also some doubt, Thorpe[127] describing it as an amorphous powder, and Howard[128] as a brownish, syrup-like mass, having a slight acid and astringent taste.

The chemical reactions of "caffetannic acid" are generally agreed upon. A dark green coloration is given with ferric chloride; and upon boiling it with alkalies or dilute acids, caffeic acid and glucose are formed. Fusion with alkali produces protocatechuic acid.

K. Gorter[129] has made an extensive and accurate investigation into the matter, and in reporting upon the same has made some very pertinent observations. His claim is that the name "caffetannic acid" is a misnomer and should be abandoned. The so-called "caffetannic acid" is really a mixture which has among its constituents chlorogenic acid (C_32_H_38_O_19), which is not a tannic acid, and coffalic acid. Tatlock and Thompson[130] have expressed the opinion that roasted coffee contains no tannin, and that the lead precipitate contains mostly coloring matter. They found only 4.5 percent of tannin (precipitable by gelatin or alkaloids) in raw coffee.

Hanausek[131] demonstrated the presence of oxalic acid in unripe beans, and citric acid has been isolated from Liberian coffee. It also has been claimed that viridic acid, C_14_H_20_O_11, is present in coffee. In addition to these, the fat of coffee contains a certain percentage of free fatty acids.

It is thus apparent that even in green coffee there is no definite compound "caffetannic acid," and there is even less likelihood of its being present in roasted coffee. The conditions, high heat and oxidation, to which coffee is subjected in roasting would suffice to decompose this hypothetical acid if it were present.

In the method of analysis for caffetannic acid (No. 24) given at the end of this chapter, there are many chances of error, although this procedure is the best yet devised. Lead acetate forms three different compounds with "caffetannic acid," so that this reagent must be added with extreme care in order to precipitate the compound desired. The precipitate, upon forming, mechanically carries down with it any fats which may be present, and which are removed from it only with difficulty. The majority of the mineral salts in the solution will come down simultaneously. All of the above-mentioned organic acids form insoluble salts with lead acetate, and there will also be a tendency toward precipitation of certain of the components of caramel, the acidic polymerization products of acrolein, glycerol, etc., and of the proteins and their decomposition products.

In view of this condition of uncertainty in composition, necessity for great care in manipulation, and ever-present danger of contamination, the significance of "caffetannic acid analysis" fades. It is highly desirable that the nomenclature relevant to this analytical procedure be changed to one, such as "lead number," which will be more truly indicative of its significance.

The Alkaloids of Coffee

In addition to caffein, the main alkaloid of coffee, trigonellin--the methylbetaine of nicotinic acid--sometimes known as caffearine, has been isolated from coffee.[132] This alkaloid, having the formula C_14_H_16_O_4_N_2, is also found in fenugreek, Trigonella foenum-graecum, in various leguminous plants, and in the seeds of strophanthus. When pure it forms colorless needles melting at 140 deg. C., and, as with all alkaloids, gives a weak basic reaction. It is very soluble in water, slightly soluble in alcohol, and only very slightly soluble in ether, chloroform or benzol, so that it does not contaminate the caffein in the determination of the latter. Its effects on the body have not been studied, but they are probably not very great, as Polstorff obtained only 0.23 percent from the coffee which he examined.

Caffein, thein, trimethylxanthin, or C_5_H(CH_3)_3_N_4_O_2, in addition to being in the coffee bean is also found in guarana leaves, the kola nut, mate, or Paraguay tea, and, in small quantities, in cocoa. It is also found in other parts of these plants besides those commonly used for food purposes.

A neat test for detecting the presence of caffein is that of A. Viehoever,[133] in which the caffein is sublimed directly from the plant tissue in a special apparatus. The presence of caffein in the sublimate is verified by observing its melting point, determined on a special heating stage used in connection with a microscope.

The chief commercial source of this alkaloid is waste and damaged tea, from which it is prepared by extraction with boiling water, the tannin precipitated from the solution with litharge, and the solution then concentrated to crystallize out the caffein. It is further purified by sublimation or recrystallization from water. Coffee chaff and roaster-flue dust have been proposed as sources for medicinal caffein, but the extraction of the alkaloid from the former has not proven to be a commercial success. Several manufacturers of pharmaceuticals are now extracting caffein from roaster-flue dust, probably by an adaptation of the Faunce[134] process. The recovery of caffein from roaster-flue gases may be facilitated and increased by the use of a condenser such as proposed Ewe.[135]

Pure caffein forms long, white, silky, flexible needles, which readily felt together to form light, fleecy masses. It melts at 235-7 deg. C. and sublimes completely at 178 deg. C., though the sublimation starts at 120 deg. Salts of an unstable nature are formed with caffein by most acids. The solubility of caffein as determined by Seidell[136] is given in Table I.

TABLE I--THE SOLUBILITY OF CAFFEIN

Solubility: Grm. Caffein per 100 Grm. of Sp. Gr. of Sp. Gr. of Temperature Saturated Saturated Solvent Solvent of Solution Solution Solution

Water 0.997 25 2.14 Ether 0.716 25 0.27 Chloroform 1.476 25 11.0 Acetone 0.809 30-1 2.18 0.832 Benzene 0.872 30-1 1.22 0.875 Benzaldehyde 1.055 30-1 11.62 1.087 Amylacetate 0.860 30-1 0.72 0.862 Aniline 1.02 30-1 22.89 1.080 Amyl alcohol 0.814 25 0.49 0.810 Acetic acid 1.055 21.5 2.44 Xylene 0.847 32.5 1.11 0.847 Toluene 0.862 25 0.57 0.861

The similarity between caffein and theobromin (the chief alkaloid of cocoa), xanthin (one of the constituents of meat), and uric acid, is shown by the accompanying structural formulae.

These formulae show merely the relative position occupied by caffein in the purin group, and do not in any wise indicate, because of its similarity of structure to the other compounds, that it has the same physiological action. The presence and position of the methyl groups (CH_3) in caffein is probably the controlling factor which makes its action differ from the behavior of other members of the series. The structure of these compounds was established, and their syntheses accomplished, in the course of various classic researches by Emil Fischer.[137]

Gorter states that caffein exists in coffee in combination with chlorogenic acid as a potassium chlorogenate, C_32_H_36_O_19, K_2(C_8_H_10_O_2_N_4)_2.2H_2_O, which he isolated in colorless prisms. This compound is water-soluble, but caffein can not be extracted from the crystals with anhydrous solvents. To this behavior can probably be attributed the difficulty experienced in extracting caffein from coffee with dry organic solvents. However, the fact that a small percentage can be extracted from the green bean in this manner indicates that some of the caffein content exists therein in a free state. This acid compound of caffein will be largely decomposed during the process of torrefaction, so that in roasted coffee a larger percentage will be present in the free state. Microscopical examination of the roasted bean lends verisimilitude to this contention.

TABLE II--COFFEE ANALYSES

Santos Green | Santos Roasted | | Padang Green | | | Padang Roasted | | | | Guatemala Green | | | | | Guatemala Roasted | | | | | | Mocha Green | | | | | | | Mocha | | | | | | | Roasted | | | | | | | | Moisture 8.75 3.75 8.78 2.72 9.59 3.40 9.06 3.36 April 20th Moisture September 20th 8.12 6.45 8.05 6.03 8.68 6.92 8.15 7.10 Ash 4.41 4.49 4.23 4.70 3.93 4.48 4.20 4.43 Oil 12.96 13.76 12.28 13.33 12.42 13.07 14.04 14.18 Caffein 1.87 1.81 1.56 1.47 1.26 1.22 1.31 1.28 Caffein, dry basis 2.03 .... 1.69 .... 1.39 .... 1.44 .... Crude fiber 20.70 14.75 21.92 14.95 22.23 15.23 22.46 15.41 Protein 9.50 12.93 12.62 14.75 10.43 11.69 8.56 9.57 Protein, dry basis 10.41 .... 13.68 .... 11.53 .... 9.41 .... Water extract 31.11 30.30 30.83 30.21 31.04 30.47 31.27 30.44 Specific gravity, 10 percent extract 1.0109 1.0101 1.0107 1.0104 1.0105 1.0104 1.0108 1.0108 Bushelweight 47.0 28.2 45.2 27.8 52.2 27.2 48.8 30.2 1,000 kernel weight 130.60 120.20 167.30 151.35 189.20 165.80 119.52 100.00 1,000 kernel weight, dry basis 119.1 115.7 154.1 147.2 171.0 160.1 108.6 96.6 Dextrose .... 0.72 .... 0.81 .... 0.54 .... 0.46 Caffetannic acid 15.58 17.44 15.37 16.93 16.27 17.13 15.61 16.89 Acidity by titration apparent 1.50 2.08 1.47 2.00 1.39 2.13 1.11 1.87

As may be seen in Table II,[138] the caffein content of coffee varies with the different kinds, a fair average of the caffein content being about 1.5 percent for C. arabica, to which class most of our coffees belong. However, aside from these may be mentioned C. canephora, which yields 1.97 percent caffein; C. mauritiana, which contains 0.07 percent of the alkaloid (less than the average "caffein-free coffee"); and C. humboltiana, which contains no caffein, but a bitter principle, cafemarin. Neither do the berries of C. Gallienii, C. Bonnieri, or C. Mogeneti contain any caffein; and there has also been reported[139] a "Congo coffee" which contained no crystallizable alkaloid whatever.

Apparently the variation in caffein content is largely due to the genus of the tree from which the berry comes, but it is also quite probable that the nature of the soil and climatic conditions play an important part. In the light of what has been accomplished in the field of agricultural research, it does not seem improbable that a man of Burbank's ability and foresight could successfully develop a series of coffees possessed of all the cup qualities inherent in those now used, but totally devoid of caffein. Whether this is desirable or not is a question to be considered in an entirely different light from the possibility of its accomplishment.

TABLE III--CAFFEIN IN DIFFERENT ROASTS

Rio Santos Guatemala

Green 1.68% 1.85% 1.82% Cinnamon 1.70 1.72 1.80 Medium 1.66 1.66 1.56 City 1.36 1.66 1.46

The variation in the caffein content of coffee at different intensities of roasting, as shown in Table III[140] is, of course, primarily dependent upon the original content of the green. A considerable portion of the caffein is sublimed off during roasting, thus decreasing the amount in the bean. The higher the roast is carried, the greater the shrinkage; but, as the analyses in the above table show, the loss of caffein proceeds out of proportion to the shrinkage, for the percentage of caffein constantly decreases with the increase in color. If the roast be carried almost to the point of carbonization, as in the case of the "Italian roast," the caffein content will be almost nil. This is not a suitable coffee for one desiring an almost caffein-free drink, for the empyreumatic products produced by this excessive roasting will be more toxic by far than the caffein itself would have been.

Caffein-free Coffee

The demand for a caffein-free coffee may be attributed to two causes, namely: the objectionable effect which caffein has upon neurasthenics; and the questionable advertising of the "coffee-substitute" dealers, who have by this means persuaded many normal persons into believing that they are decidedly sub-normal. As a result of this demand, a variety of decaffeinated coffees have been placed on the market. Just why the coffee men have not taken advantage of naturally caffein-free coffees, or of the possibility of obtaining coffees low in caffein content by chemical selection from the lines now used, is a difficult question to answer.

In the endeavor to develop a commercial decaffeinated coffee the first method of procedure was to extract the caffein from roasted coffee. This method had its advantages and its disadvantages, of which the latter predominated. The caffein in the roasted coffee is not as tightly bound chemically as in the green coffee, and is, therefore, more easily extracted. Also, the structure of the roasted bean renders it more readily penetrable by solvents than does that of the green bean. However, the great objection to this method arises from the fact that at the same time as the caffein is extracted, the volatile aromatic and flavoring constituents of the coffee are removed also. These substances, which are essential for the maintenance of quality by the coffee, though readily separated from the caffein, can not be returned to the roasted bean with any degree of certainty. This virtually insurmountable obstacle forced the abandonment of this mode of attack.

In order to avoid this action, the attention of investigators was directed to extraction of the alkaloid in question from the green bean. Because of the difficulty of causing the solvent to penetrate the bean, recourse to grinding resulted. This greatly facilitated the desired extraction, but a difficulty was encountered when the subsequent roasting was attempted. The irregular and broken character of the ground green beans resisted all attempts to produce practically a uniformly roasted, highly aromatic product from the ground material.

Avoidance of this lack of uniformity in the product, and the great desirability to duplicate the normal bean as far as possible, necessitated the development of a method of extraction of the caffein from the whole raw bean without a permanent alteration of the shape thereof. The close structure of the green bean, and its consequent resistance to penetration by solvents, and the existence of the caffein in the bean as an acid salt, which is not easily soluble, offered resistance to successful extraction.

As a means of overcoming the difficulty of structure, the beans were allowed to stand in water in order to swell, or the cells were expanded by treatment with steam, or the beans were subjected to the action of some "cellulose-softening acids," such as acetic acid or sulphur dioxid. As a method of facilitating the mechanical side of extraction without deleterious effects, the treatment of the coffee with steam under pressure, as utilized in the patented process of Myer, Roselius, and Wimmer,[141] is probably the safest.

Many ingenious methods have been devised for the ready removal of the caffein from this point on. Several processes employ an alkali, such as ammonium hydroxid, to free the caffein from the acid; or an acid, such as acetic, hydrochloric, or sulphurous, is used to form a more soluble salt of caffein. Other procedures effect the dissociation of the caffein-acid salt by dampening or immersion in a liquid and subjecting the mass to the action of an electric current.

The caffein is usually extracted from the beans by benzol or chloroform, but a variety of solvents may be employed, such as petrolic ether, water, alcohol, carbon tetrachloride, ethylene chloride, acetone, ethyl ether, or mixtures or emulsions of these. After extraction, the beans may be steam distilled to remove and to recover any residual traces of solvent, and then dried and roasted. It is said[142] that by heating the beans before bringing them into contact with steam, not only is an economy of steam effected, but the quality of the resultant product is improved.

One clever but expensive method[143] of preparing caffein-free coffee consists in heating the beans under pressure, with some substance, such as sodium salicylate, with the resultant formation of a more soluble and more easily steam-distillable compound of caffein. The beans are then steam distilled to remove the caffein, dried, and roasted.

Another process of peculiar interest is that of Hubner,[144] in which the coffee beans are well washed and then spread in layers and kept covered with water at 15 deg. C. until limited germination has taken place, whereupon the beans are removed and the caffein extracted with water at 50 deg. C. It is claimed by the inventor that sprouting serves to remove some of the caffein, but it is quite probable that the process does nothing more than accomplish simple aqueous extraction.

In the majority of these processes the flavor of the resultant product should be very similar to natural roasted coffee. However, in the cases where aqueous extraction is employed, other substances besides caffein are removed that are replaced in the bean only with difficulty. The resultant product accordingly is very likely to have a flavor not entirely natural. On the other hand, beans from which the caffein is extracted with volatile solvents, if the operation be conducted carefully, should give a natural-tasting roast. Any residual traces of the solvent left in the bean are volatilized upon roasting.

Some of the caffein-free coffees on the market show upon analysis almost as much caffein as the natural bean. Those manufactured by reliable concerns, however, are virtually caffein-free, their content of the alkaloid varying from 0.3 to 0.07 percent as opposed to 1.5 percent in the untreated coffee. Thus, although actually only caffein-poor, in order to get the reaction of one cup of ordinary coffee one would have to drink an unusual amount of the brew made from these coffees.

The Aromatic Principles of Coffee

To ascertain just what substance or substances give the pleasing and characteristic aroma to coffee has long been the great desire of both practical and scientific men interested in the coffee business. This elusive material has been variously called caffeol, caffeone, "the essential oil of coffee," etc., the terms having acquired an ambiguous and incorrect significance. It is now generally agreed that the aromatic constituent of coffee is not an essential oil, but a complex of compounds which usage has caused to be collectively called "caffeol."

These substances are not present in the green bean, but are produced during the process of roasting. Attempts at identification and location of origin have been numerous; and although not conclusive, still have not proven entirely futile. One of the first observations along this line was that of Benjamin Thompson in 1812. "This fragrance of coffee is certainly owing to the escape of a volatile aromatic substance which did not originally exist as such in the grain, but which is formed in the process of roasting it." Later, Graham, Stenhouse, and Campbell started on the way to the identification of this aroma by noting that "in common with all the valuable constituents of coffee, caffeone is found to come from the soluble portion of the roasted seed."[145]

Comparison of the aroma given off by coffee during the roasting process with that of fresh-ground roasted coffee shows that the two aromas, although somewhat different, may be attributed to the same substances present in different proportions in the two cases. Recovery and identification of the aromatic principles escaping from the roaster would go far toward answering the question regarding the nature of the aroma. Bernheimer[146] reported water, caffein, caffeol, acetic acid, quinol, methylamin, acetone, fatty acids and pyrrol in the distillate coming from roasting coffee. The caffeol obtained by Bernheimer in this work was believed by him to be a methyl derivative of saligenin. Jaeckle[147] examined a similar product and found considerable quantities of caffein, furfurol, and acetic acid, together with small amounts of acetone, ammonia, trimethylamin, and formic acid. The caffeol of Bernheimer could not be detected. Another substance was separated also, but in too small a quantity to permit complete identification. This substance consisted of colorless crystals, which readily sublimed, melted at 115 deg. to 117 deg. C., and contained sulphur. The crystals were insoluble in water, almost insoluble in alcohol, but readily soluble in ether.

By distilling roasted coffee with superheated steam, Erdmann[148] obtained an oil consisting of an indifferent portion of 58 percent and an acid portion of 42 percent, consisting mainly of a valeric acid, probably alphamethylbutyric acid. The indifferent portion was found to contain about 50 percent furfuryl alcohol, together with a number of phenols. The fraction containing the characteristic odorous constituent of coffee boiled at 93 deg. C. under 13 mm. pressure. The yield of this latter principle was extremely small, only about 0.89 gram being procured from 65 kilos of coffee.

Pyridin was also shown to be present in coffee by Betrand and Weisweiller[149] and by Sayre.[150] As high as 200 to 500 milligrams of this toxic compound have been obtained from 1 kilogram of freshly roasted coffee.

As stated above, the empyreumatic volatile aromatic constituents of the coffee are without question formed during and by the roasting process. According to Thorpe,[151] the most favorable temperature for development of coffee odor and flavor is about 200 deg. C. Erdmann claimed to have produced caffeol by gently heating together caffetannic acid, caffein, and cane sugar. Other investigators have been unable to duplicate this work. Another authority,[152] giving it the empirical formula C_8_H_10_O_2, states that it is produced during roasting, probably at the expense of a portion of the caffein. These conceptions are in the main incomplete and inaccurate.

By means of careful work, Grafe[153] came closer to ascertaining the origin of the fugacious aromatic materials. His work with normal, caffein-free coffee and with Thum's purified coffee led him to state that a part of these substances was derived from the crude fiber, probably from the hemi-cellulose of the thick endosperm cells. Sayre[154] makes the most plausible proposal regarding the origin of caffeol. He considers the roasting of coffee as a destructive distillation process, summarizing the results, briefly, as the production of furfuraldehyde from the carbohydrates, acrolein from the fats, catechol and pyrogallol from the tannins, and ammonia, amins, and pyrrols from the proteins. The products of roasting inter-react to produce many compounds of varying degrees of complexity and toxicity.

The great difficulty which arises in the attempt to identify the aromatic constituents of coffee is that the caffeols of no two coffees may be said to be the same. The reason for this is apparent; for the green coffees themselves vary in composition, and those of the same constitution are not roasted under identical conditions. Therefore, it is not to be expected that the decomposition products formed by the action of the different greens would be the same. Also, these volatile products occur in the roasted coffee in such a small amount that the ascertaining of their percentage relationship and the recognition of all that are present are not possible with the methods of analysis at present at our disposal. Until better analytical procedures have been developed we can not hope to establish a chemical basis for the grading of coffees from this standpoint.

Coffee Oil and Fat

It is well to distinguish between the "coffee oils," as they are termed by the trade, and true coffee oil. In speaking of the qualities of coffee, connoisseurs frequently use erroneous terms, particularly when they designate certain of the flavoring and aromatic constituents of coffee as "oils" or "essential oils." Coffee does not contain any essential oils, the aromatic constituent corresponding to essential oil in coffee being caffeol, a complex which is water-soluble, a property not possessed by any true oil. True, the oil when isolated from roasted coffee does possess, before purification, considerable of the aromatic and flavoring constituents of coffee. They are, however, no part of the coffee fat, but are held in it no doubt by an enfleurage action in much the same way that perfumes of roses, etc., are absorbed and retained by fats and oils in the commercial preparation of pomades and perfumes. This affinity of the coffee oil for caffeol assists in the retention of aromatic substances by the whole roasted bean. However, upon extraction of ground roasted coffee with water, the caffeol shows a preferential solubility in water, and is dissolved out from the oil, going into the brew.

The true oil of coffee has been investigated to a fair degree and has been found to be inodorous when purified. Analysis of green and roasted coffees shows them to possess between 12 percent and 20 percent fat. Warnier[155] extracted ground unroasted coffee with petroleum ether, washed the extract with water, and distilled off the solvent, obtaining a yellow-brownish oil possessing a sharp taste. From his examination of this oil he reported these constants: d_24-5, 0.942; refraction at 25 deg., 81.5; solidifying point, 6 deg. to 5 deg.; melting point, 8 deg. to 9 deg.; saponification number, 177.5; esterification number, 166.7; acid number, 6.2; acetyl number, 0; iodin number, 84.5 to 86.3. Meyer and Eckert[156] carefully purified coffee oil and saponified it with Li_2_O in alcohol. In the saponifiable portion, glycerol was the only alcohol present, the acids being carnaubic, 10 percent; daturinic acid, 1 to 1.5 percent; palmitic acid, 25 to 28 percent; capric acid, 0.5 percent; oleic acid, 2 percent, and linoleic acid, 50 percent. The unsaponifiable wax amounted to 21.2 percent, was nitrogen-free, gave a phytostearin reaction, and saponification and oxidation indicated that it was probably a tannol carnaubate. Von-Bitto[157] examined the fat extracted from the inner husk of the coffee berry and found it to be faint yellow in color, and to solidify only gradually after melting. Upon analysis, it showed: saponification value, 141.2; palmitic acid, 37.84 percent, and glycerids as tripalmitin, 28.03 percent.

Carbohydrates of the Coffee Berry

There has been considerable diversity of opinion regarding the sugar of coffee. Bell believed the sugar to be of a peculiar species allied to melezitose, but Ewell,[158] G.L. Spencer, and others definitely proved the presence of sucrose in coffee. In fat-free coffee 6 percent of sucrose was found extractable by 70 percent alcohol. Baker[159] claimed that manno-arabinose, or manno-xylose, formed one of the most important constituents of the coffee-berry substance and yielded mannose on hydrolysis. Schultze and Maxwell state that raw coffee contains galactan, mannan, and pentosans, the latter present to the extent of 5 percent in raw and 3 percent in roasted coffee. By distilling coffee with hydrochloric acid Ewell obtained furfurol equivalent to 9 percent pentose. He also obtained a gummy substance which, on hydrolysis, gave rise to a reducing sugar; and as it gave mucic acid and furfurol on oxidation, he concluded that it was a compound of pentose and galactose. In undressed Mysore coffee Commaille[160] found 2.6 percent of glucose and no dextrin. This claim of the presence of glucose in coffee was substantiated by the work of Hlasiwetz,[161] who resolved a caffetannic acid, which he had isolated, into glucose and a peculiar crystallizable acid, C_8_H_8_O_4, which he named caffeic acid.

The starch content of coffee is very low. Cereals may readily be detected and identified in coffee mixtures by the presence and characteristics of their starch, in view of the fact that coffee (chicory, too) is practically free from starch. On this score it is inadvisable for diabetics to use any of the many cereal substitutes for coffee. It is pertinent to note in this connection that persons suffering from diabetes may sweeten their coffee with saccharin (1/2 to 1 grain per cup) or glycerol, thus obtaining perfect satisfaction without endangering their health.

The cellulose in coffee is of a very hard and horny character in the green bean, but it is made softer and more brittle during the process of roasting. It is rather difficult to define under the microscope, particularly after roasting, even though the chief characteristics of the cellular tissue are more or less retained. Coffee cellulose gives a blue color with sulphuric acid and iodin, and is dissolved by an ammoniacal solution of copper oxid. Even after roasting, remnants of the silver skin are always present, the structure of which, a thin membrane with adherent, thick-walled, spindle-shaped, hollow cells, is peculiar to coffee.

The Chemistry of Roasting

The effect of the heat in the roasting of coffee is largely evidenced as a destructive distillation and also as a partial dehydration. At the same time, oxidizing and reducing reactions probably occur within the bean, as well as some polymerization and inter-reactions.

A loss of water is to be expected as the natural outcome of the application of heat; and analyses show that the moisture content of raw coffee varies from 8 to 14 percent, while after roasting it rarely exceeds 3 percent, and frequently falls as low as 0.5 percent. The loss of the original water content of the green bean is not the only moisture loss; for many of the constituents of coffee, notably the carbohydrates, are decomposed upon heating to give off water, so that analysis before and after roasting is no direct indication of the exact amount of water driven off in the process. If it be desired to ascertain this quantity accurately, catching of the products which are driven off and determination of their water content becomes necessary.

The carbohydrates both dehydrate and decompose. The result of the dehydration is the formation of caramel and related products, which comprise the principal coloring matters in coffee infusion. That portion of the carbohydrates known as pentosans gives rise to furfuraldehyde, one of the important components of caffeol.

The effect of roasting upon the fat content of the beans is to reduce its actual weight, but not to change appreciably the percentage present, since the decrease in quantity keeps pace fairly well with the shrinkage. Some of the more volatile fatty acids are driven off, and the fats break down to give a larger percentage of free fatty acids, some light esters, acrolein, and formic acid. If the roast be a very heavy one, or is brought up too rapidly, the fat will come to the surface, through breaking of the fat cells, with a decided alteration in the chemical nature of the fat and with pronounced expansion and cracking.

Decomposition of the caffein acid-salt and considerable sublimation of the caffein also occur. The majority of the caffein undergoes this volatilization unchanged, but a portion of it is probably oxidized with the formation of ammonia, methylamin, di-methylparabanic acid, and carbon dioxid. This reaction partly explains why the amount of caffein recovered from the roaster flues is not commensurate with the amount lost from the roasting coffee; although incomplete condensation is also an important factor. Microscopic examination of the roasted beans will show occasional small crystals of caffein in the indentations on the surface, where they have been deposited during the cooling process.

The compound, or compounds, known as "caffetannic acid" are probably the source of catechol, as the proteins are of ammonia, amins, and pyrrols. The crude fiber and other unnamed constituents of the raw beans react analogously to similar compounds in the destructive distillation of wood, giving rise to acetone, various fatty acids, carbon dioxid and other uncondensable gases, and many compounds of unknown identity.

During the course of roasting and subsequent cooling these decomposition products probably interact and polymerize to form aromatic tar-like materials and other complexes which play an important role among the delicate flavors of coffee. In fact, it is not unlikely that these reactions continue throughout the storage time after roasting, and that upon them the deterioration of roasted coffee is largely dependent. Speculation upon what complex compounds are thus formed offers much attraction. A notable one by Sayre[162] postulates the reaction between acrolein and ammonia to give methyl pyridin, which in turn with furfurol forms furfurol vinyl pyridin. This upon reduction would produce the alkaloid, conin, traces of which have been found in coffee.

Although furfuraldehyde is the natural decomposition product of pentosans, furfuryl alcohol is the main furane body of coffee aroma. This would indicate that active reducing conditions prevail within the bean during roasting; and the further fact that carbon monoxid is given off during roasting makes this seem quite probable. If one admits that caffetannic acid exists in the green bean; that upon oxidation it gives viridic acid; and that it is concentrated in the outer layers of the bean, as certain investigators have claimed, then there is chemical proof of the existence of oxidizing conditions about the exterior of the bean. In any event, however, the fact that oxidizing conditions predominate on the external portion of the bean is obvious. Accordingly, our meager knowledge of the chemistry of roasting indicates that while the external layers of the roasting beans are subjected to oxidizing conditions, reducing ones exist in the interior. Future experimentation will, no doubt, prove this to be the case.

Attempts have been made to retain in the beans the volatile products, which normally escape, both by coating previous to roasting[163] and by conducting the process under pressure.[164] However, the results so obtained were not practical, since the cup values were decreased in the majority of cases, and the physiological effects produced were undesirable. In cases where the quality was improved, the gain was not sufficient to recompense the roaster for the additional expense and difficulty of operation.

Various persons have essayed to control the roasting process automatically; but the extreme variance in composition of different coffees, the effect of changing atmospheric conditions, and the lack of constancy in the calorific power of fuels have conspired to defeat the automatic roasting machine.[165] It is even doubtful whether De Mattia's[166] process for roasting until the vapors evolved produce a violet color when passed into a solution of fuchsin decolorized with sulphur dioxid is commercially reliable.

Many patents have been granted for the treatment of coffees immediately prior to or during roasting with the object of thus improving the product. The majority of these depend upon adding solutions of sugar,[167] calcium saccharate,[168] or other carbohydrates,[169] and in the case of Eckhardt,[170] of small percentages of tannic acid and fat. In direct opposition to this latter practise, Jurgens and Westphal[171] apply alkali, ostensibly to lessen the "tannic acid" content. Brougier[172] sprays a solution containing caffein upon the roasting berries; and Potter[173] roasts the coffee together with chicory, effecting a separation at the end.

The exact effect which roasting with sugars has upon the flavor is not well understood; but it is known that it causes the beans to absorb more moisture, due to the hygroscopicity of the caramel formed. For instance, berries roasted with the addition of glucose syrup hold an additional 7 percent of water and give a darker infusion than normally roasted coffee. When the green coffee is glazed with cane sugar prior to roasting, the losses during the process are much higher than ordinarily, on account of the higher temperature required to attain the desired results. Losses for ordinary coffee taken to a 16-percent roast are 9.7 percent of the original fat and 21.1 percent of the original caffein; while for "sugar glazed" coffee the losses were 18.3 percent of the original fat and 44.3 percent of the original caffein, using 8 to 9 percent sugar with Java coffee.

Grinding and Packaging

It is a curious fact that green coffee improves upon aging, whereas after roasting it deteriorates with time. Even when packed in the best containers, age shows to a disadvantage on the roasted bean. This is due to a number of causes, among which are oxidation, volatilization of the aroma, absorption of moisture and consequent hydrolysis, and alteration in the character of the aromatic principles. Doolittle and Wright[174] in the course of some extensive experiments found that roasted coffee showed a continual gain in weight throughout 60 weeks, this gain being mostly due to moisture absorption. An investigation by Gould[175] also demonstrated that roasted coffee gives off carbon dioxid and carbon monoxid upon standing. The latter, apparently produced during roasting and retained by the cellular structure of the bean, diffuses therefrom; whereas the former comes from an ante-roasting decomposition of unstable compounds present.[176]

The surface of the whole bean forms a natural protection against atmospheric influences, and as soon as this is broken, deterioration sets in. On this account, coffee should be ground immediately before extraction if maximum efficiency is to be obtained. The cells of the beans tend to retain the fugacious aromatic principles to a certain extent; so that the more of these which are broken in grinding, the greater will be the initial loss and the more rapid the vitiation of the coffee. It might, therefore, seem desirable to grind coarsely in order to avoid this as much as possible. However, the coarser the grind, the slower and more incomplete will be the extraction. A patent[177] has been granted for a grind which contains about 90 percent fine coffee and 10 percent coarse, the patentee's claim being that in his "irregular grind" the coarse coffee retains enough of the volatile constituents to flavor the beverage, while the fine coffee gives a very high extraction, thus giving an efficient brew without sacrificing individuality.

In packaging roasted coffee the whole bean is naturally the best form to employ, but if the coffee is ground first, King[178] found that deterioration is most rapid with the coarse ground coffee, the speed decreasing with the size of the ground particles. He explains this on the ground of "ventilation"--the finer the grind, the closer the particles pack together, the less the circulation of air through the mass, and the smaller the amount of aroma which is carried away. He also found that glass makes the best container for coffee, with the tin can, and the foil-lined bag with an inner lining of glassine, not greatly inferior.

Considerable publicity has been given recently to the method of packing coffee in a sealed tin under reduced pressure. While thus packing in a partial vacuum undoubtedly retards oxidation and precludes escape of aroma from the original package, it would seem likely to hasten the initial volatilizing of the aroma. Also, it would appear from Gould's[179] work that roasted coffee evolves carbon dioxid until a certain positive pressure is attained, regardless of the initial pressure in the container. Accordingly, vacuum-packing apparently enhances decomposition of certain constituents of coffee. Whether this result is beneficial or otherwise is not quite clear.

Brewing

The old-time boiling method of making coffee has gone out of style, because the average consumer is becoming aware of the fact that it does not give a drink of maximum efficiency. Boiling the ground coffee with water results in a large loss of aromatic principles by steam distillation, a partial hydrolysis of insoluble portions of the grounds, and a subsequent extraction of the products thus formed, which give a bitter flavor to the beverage. Also, the maintenance of a high temperature by the direct application of heat has a deleterious effect upon the substances in solution. This is also true in the case of the pumping percolator, and any other device wherein the solution is caused to pass directly into steam at the point where heat is applied. Warm and cold water extract about the same amount of material from coffee; but with different rates of speed, an increase in temperature decreasing the time necessary to effect the desired result.

It is a well known fact that re-warming a coffee brew has an undesirable effect upon it. This is very probably due to the precipitation of some of the water-soluble proteins when the solution cools, and their subsequent decomposition when heat is applied directly to them in reheating the solution. The absorption of air by the solution upon cooling, with attendant oxidation, which is accentuated by the application of heat in re-warming, must also be considered. It is likewise probable that when an extract of coffee cools upon standing, some of the aromatic principles separate out and are lost by volatilization.

The method of extracting coffee which gives the most satisfaction is practised by using a grind just coarse enough to retain the individualistic flavoring components, retaining the ground coffee in a fine cloth bag, as in the urn system, or on a filter paper, as in the Tricolator, and pouring water at boiling temperature over the coffee. During the extraction, a top should be kept on the device to minimize volatilization, and the temperature of the extract should be maintained constant at about 200 deg. F. after being made. Whether a repouring is necessary or not is dependent upon the speed with which the water passes through the coffee, which in turn is controlled by the fineness of the grind and of the filtering medium.

The Water Extract

Although many analyses of the whole coffee bean are available, but little work has been reported upon the aqueous extracts. The total water extract of roasted coffee varies from 20 to 31 percent in different kinds of coffee. The following analysis of the extract from a Santos coffee may be taken as a fair average example of the water-soluble material.[180]

TABLE IV--ANALYSIS OF SANTOS COFFEE EXTRACT (DRY BASIS)

Ether extract, fixed 1.06% Total nitrogen 3.40% Caffein 5.42% Crude fiber 0.25% Total ash 17.43% Reducing sugar 2.70% Caffetannic acid 15.33% Protein 7.71%

It is difficult to make the trade terms, such as acidity, astringency, etc., used in describing a cup of coffee, conform with the chemical meanings of the same terms. However, a fair explanation of the cause of some of these qualities can be made. Careful work by Warnier[181] showed the actual acidities of some East India coffees to be:

TABLE V--ACIDITY OF SOME EAST INDIA COFFEES

Coffee from Acid Content Sindjai 0.033% Timor 0.028% Bauthain 0.019% Boengei 0.016% Loewae 0.021% Waloe Pengenten 0.018% Kawi Redjo 0.015% Palman Tjiasem 0.022% Malang 0.013%

These figures may be taken as reliable examples of the true acid content of coffee; and though they seem very low, it is not at all incomprehensible that the acids which they indicate produce the acidity in a cup of coffee. They probably are mainly volatile organic acids, together with other acidic-natured products of roasting. We know that very small quantities of acids are readily detected in fruit juices and beer, and that variation in their percentage is quickly noticed, while the neutralization of this small amount of acidity leaves an insipid drink. Hence, it seems quite likely that this small acid content gives to the coffee brew its essential acidity. A few minor experiments on neutralization have proven that a very insipid beverage is produced by thus treating a coffee infusion.

The body, or what might be called the licorice-like character, of coffee, is due conceivably to the presence of bodies of a glucosidic nature and to caramel. Astringency, or bitterness, is dependent upon the decomposition products of crude fiber and chlorogenic acid, and upon the soluble mineral content of the bean. The degree to which a coffee is sweet-tasting or not is, of course, dependent upon its other characteristics, but probably varies with the reducing sugar content. Aside from the effects of these constituents upon cup quality, the influence of volatile aromatic and flavoring constituents is always evident in the cup valuation, and introduces a controlling factor in the production of an individualistic drink.

Coffee Extracts

The uncertainty of the quality of coffee brews as made from day to day, the inconvenience to the housewife of conducting the extraction, and the inevitable trend of the human race toward labor-saving devices, have combined their influences to produce a demand for a substance which will give a good cup of coffee when added to water. This gave rise to a number of concentrated liquid and solid "extracts of coffee," which, because of their general poor quality, soon brought this type of product into disrepute. This is not surprising; for these preparations were mainly mixtures of caramel and carelessly prepared extracts of chicory, roasted cereals, and cheap coffee.

Liquid extracts of coffee galore have appeared on the market only soon to disappear. Difficulty is experienced in having them maintain their quality over a protracted period of time, primarily due to the hydrolyzing action of water on the dissolved substances. They also ferment readily, although a small percentage of preservative, such as benzoate of soda, will halt spoilage.[182]

So much trouble is not encountered with coffee-extract powders--the so-called "soluble" or "instant" coffees. The majority of these powdered dry extracts do, however, show great affinity for atmospheric moisture. Their hygroscopicity necessitates packing and keeping them in air-tight containers to prevent them running into a solid, slowly soluble mass.

The general method of procedure employed in the preparation of these powders is to extract ground roasted coffee with water, and to evaporate the aqueous solution to dryness with great care. The major difficulty which seems to arise is that the heat needed to effect evaporation changes the character of the soluble material, at the same time driving off some volatile constituents which are essential to a natural flavor. Many complex and clever processes have been developed for avoiding these difficulties, and quite a number of patents on processes, and several on the resultant product, have been allowed; but the commercial production of a soluble coffee of freshly-brewed-coffee-duplicating-power is yet to be accomplished. However, there are now on the market several coffee-extract powders which dissolve readily in water, giving quite a fair approximation of freshly brewed coffee. The improvement shown since they first appeared augurs well for the eventual attainment of their ultimate goal.

Adulterants and Substitutes

There would appear to be three reasons why substitutes for coffee are sought--the high cost, or absence, of the real product; the acquiring of a preferential taste, by the consumer, for the substitute; and the injurious effects of coffee when used to excess. Makers of coffee substitutes usually emphasize the latter reason; but many substitutes, which are, or have been, on the market, seem to depend for their existence on the other two. Properly speaking, there are scarcely any real substitutes for coffee. The substances used to replace it are mostly like it only in appearance, and barely simulate it in taste. Besides, many of them are not used alone, but are mixed with real coffee as adulterants.

The two main coffee substitutes are chicory and cereals. Chicory, succory, Cichorium Intybus, is a perennial plant, growing to a height of about three feet, bearing blue flowers, having a long tap root, and possessing a foliage which is sometimes used as cattle food. The plant is cultivated generally for the sake of its root, which is cut into slices, kiln-dried, and then roasted in the same manner as coffee, usually with the addition of a small proportion of some kind of fat. The preparation and use of roasted chicory originated in Holland, about 1750. Fresh chicory[183] contains about 77 percent water, 7.5 gummy matter, 1.1 of glucose, 4.0 of bitter extractive, 0.6 fat, 9.0 cellulose, inulin and fiber, and 0.8 ash. Pure roasted chicory[184] contains 74.2 percent water-soluble material, comprised of 16.3 percent water, 26.1 glucose, 9.6 dextrin and inulin, 3.2 protein, 16.4 coloring matter, and 2.6 ash; and 25.8 percent insoluble substances, namely, 3.2 percent protein, 5.7 fat, 12.3 cellulose, and 4.6 ash. The effect of roasting upon chicory is to drive off a large percentage of water, increasing the reducing sugars, changing a large proportion of the bitter extractives and inulin, and forming dextrin and caramel as well as the characteristic chicory flavor.

The cereal substitutes contain almost every type of grain, mainly wheat, rye, oats, buckwheat, and bran. They are prepared in two general ways, by roasting the grains, or the mixtures of grains, with or without the addition of such substances as sugar, molasses, tannin, citric acid, etc., or by first making the floured grains into a dough, and then baking, grinding, and roasting. Prior to these treatments, the grains may be subjected to a variety of other treatments, such as impregnation with various compounds, or germination. The effect of roasting on these grains and other substitutes is the production of a destructive distillation, as in the case of coffee; the crude fiber, starches, and other carbohydrates, etc., being decomposed, with the production of a flavor and an aroma faintly suggesting coffee.

The number, of other substitutes and imitations which have been employed are too numerous to warrant their complete description; but it will prove interesting to enumerate a few of the more important ones, such as malt, starch, acorns, soya beans, beet roots, figs, prunes, date stones, ivory nuts, sweet potatoes, beets, carrots, peas, and other vegetables, bananas, dried pears, grape seeds, dandelion roots, rinds of citrus fruits, lupine seeds, whey, peanuts, juniper berries, rice, the fruit of the wax palm, cola nuts, chick peas, cassia seeds, and the seeds of any trees and plants indigenous to the country in which the substitute is produced.

Aside from adulteration by mixing substitutes with ground coffee, and an occasional case of factitious molded berries, the main sophistications of coffee comprise coating and coloring the whole beans. Coloring of green and roasted coffees is practised to conceal damaged and inferior beans. Lead and zinc chromates, Prussian blue, ferric oxid, coal-tar colors, and other substances of a harmful nature, have been employed for this purpose, being made to adhere to the beans with adhesives. As glazes and coatings, a variety of substances have been employed, such as butter, margarin, vegetable oils, paraffin, vaseline, gums, dextrin, gelatin, resins, glue, milk, glycerin, salt, sodium bicarbonate, vinegar, Irish moss, isinglass, albumen, etc. It is usually claimed that coating is applied to retain aroma and to act as a clarifying agent; but the real reasons are usually to increase weight through absorption of water, to render low-grade coffees more attractive, to eliminate by-products, and to assist in advertising.

METHODS OF ANALYSIS OF COFFEES[185]

(Official and Tentative)

(Sole responsibility for any errors in compilation or printing of these methods is assumed by the author.)

GREEN COFFEE

1. Macroscopic Examination--Tentative

A macroscopic examination is usually sufficient to show the presence of excessive amounts of black and blighted coffee beans, coffee hulls, stones, and other foreign matter. These can be separated by hand-picking and determined gravi-metrically.

2. Coloring Matters--Tentative

Shake vigorously 100 grams or more of the sample with cold water or 70 percent alcohol by volume. Strain through a coarse sieve and allow to settle. Identify soluble colors in the solution and insoluble pigments in the sediment.

ROASTED COFFEE

3. Macroscopic Examination--Tentative

Artificial coffee beans are apparent from their exact regularity of form. Roasted legumes and lumps of chicory, when present in whole roasted coffee, can be picked out and identified microscopically. In the case of ground coffee, sprinkle some of the sample on cold water and stir lightly. Fragments of pure coffee, if not over-roasted, will float; while fragments of chicory, legumes, cereals, etc., will sink immediately, chicory coloring the water a decided brown. In all cases identify the particles that sink by microscopical examination.

4. Preparation of Sample--Official

Grind the sample to pass through a sieve having holes 0.5 mm. in diameter and preserve in a tightly stoppered bottle.

5. Moisture--Tentative

Dry 5 grams of the sample at 105 deg.--110 deg. C. for 5 hours and subsequent periods of an hour each until constant weight is obtained. The same procedure may be used, drying in vacuo at the temperature of boiling water. In the case of whole coffee, grind rapidly to a coarse powder and weigh at once portions for the determination without sifting and without unnecessary exposure to the air.

6. Soluble Solids--Tentative

Place 4 grams of the sample in a 200-cc. flask, add water to the mark, and allow the mass to infuse for eight hours, with occasional shaking; let stand 16 hours longer without shaking, filter, evaporate 50 cc. of filtrate to dryness in a flat-bottomed dish, dry at 100 deg. C., cool and weigh.

7. Ash--Official

Char a quantity of the substance, representing about 2 grams of the dry material, and burn until free of carbon at a low heat, not to exceed dull redness. If a carbon-free ash can not be obtained in this manner, exhaust the charred mass with hot water, collect the insoluble residue on a filter, burn till the ash is white or nearly so, and then add the filtrate to the ash and evaporate to dryness. Heat to low redness, until ash is white or grayish white, and weigh.

8. Ash Insoluble in Acid--Official

Boil the water-insoluble residue, obtained as directed under 9, or the total ash obtained as directed under 7, with 25 cc. of 10-percent hydrochloric acid (sp. gr. 1.050) for 5 minutes, collect the insoluble matter on a Gooch crucible or an ashless filter, wash with hot water, ignite and weigh.

9. Soluble and Insoluble Ash--Official

Heat 5 to 10 grams of the sample in a platinum dish of from 50 to 100 cc. capacity at 100 deg. C. until the water is expelled, and add a few drops of pure olive oil and heat slowly over a flame until swelling ceases. Then place the dish in a muffle and heat at low redness until a white ash is obtained. Add water to the ash, in the platinum dish, heat nearly to boiling, filter through ash-free filter paper, and wash with hot water until the combined filtrate and washings measure to about 60 cc. Return the filter and contents to the platinum dish, carefully ignite, cool and weigh. Compute percentages of water-insoluble ash and water-soluble ash.

10. Alkalinity of the Soluble Ash--Official

Cool the filtrate from 9 and titrate with N/10 hydrochloric acid, using methyl orange as an indicator.

Express the alkalinity in terms of the number of cc. of N/10 acid per 1 gram of the sample.

11. Soluble Phosphoric Acid in the Ash--Official

Acidify the solution of soluble ash, obtained in 9, with dilute nitric acid and determine phosphoric acid (P_2_O_5). For percentages up to 5 use an aliquot corresponding to 0.4 gram of substance, for percentages between 5 and 20 use an aliquot corresponding to 0.2 gram of substance, and for percentages above 20 use an aliquot corresponding to 0.1 gram of substance. Dilute to 75-100 cc., heat in a water-bath to 60 deg.-65 deg. C., and for percentages below 5 add 20-25 cc. of freshly filtered molybdate solution. For percentages between 5 and 20 add 30-35 cc. of molybdate solution. For percentages greater than 20 add sufficient molybdate solution to insure complete precipitation. Stir, let stand in the bath for about 15 minutes, filter at once, wash once or twice with water by decantation, using 25-30 cc. each time, agitate the precipitate thoroughly and allow to settle; transfer to the filter and wash with cold water until the filtrate from two fillings of the filter yields a pink color upon the addition of phenolphthalein and one drop of the standard alkali. Transfer the precipitate and filter to the beaker, or precipitating vessel, dissolve the precipitate in a small excess of the standard alkali, add a few drops of phenolphthalein solution, and titrate with the standard acid.

12. Insoluble Phosphoric Acid in the Ash--Official

Determine phosphoric acid (P_2_O_5) in the Insoluble ash by the foregoing method.

13. Chlorides--Official

Moisten 5 grams of the substance in a platinum dish with 20 cc. of a 5-percent solution of sodium carbonate, evaporate to dryness and ignite as thoroughly as possible at a temperature not exceeding dull redness. Extract with hot water, filter and wash. Return the residue to the platinum dish and ignite to an ash; dissolve in nitric acid, and add this solution to the water extract. Add a known volume of N/10 silver nitrate in slight excess to the combined solutions. Stir well, filter and wash the silver chloride precipitate thoroughly. To the filtrate and washings add 5 cc. of a saturated solution of ferric alum and a few cc. of nitric acid. Titrate the excess silver with N/10 ammonium or potassium thiocyanate until a permanent light brown color appears. Calculate the amount of chlorin.

14. Caffein--The Fendler and Stueber Method--Tentative

Pulverize the coffee to pass without residue through a sieve having circular openings 1 mm. in diameter. Treat a 10-gram sample with 10 grams of 10-percent ammonium hydroxid and 200 grams of chloroform in a glass-stoppered bottle and shake continuously by machine or hand for one-half hour. Pour the entire contents of the bottle on a 12.5-cm. folded filter, covering with a watch glass. Weigh 150 grams of the filtrate into a 250-cc. flask and evaporate on the steam bath, removing the last chloroform with a blast of air. Digest the residue with 80 cc. of hot water for ten minutes on a steam bath with frequent shaking, and let cool. Treat the solution with 20 cc. (for roasted coffee) or 10 cc. (for unroasted coffee) of 1-percent potassium permanganate and let stand for 15 minutes at room temperature. Add 2 cc. of 3-percent hydrogen peroxid (containing 1 cc. of glacial acetic acid in 100 cc.). If the liquid is still red or reddish, add hydrogen peroxid, 1 cc. at a time, until the excess of potassium permanganate is destroyed. Place the flask on the steam bath for 15 minutes, adding hydrogen peroxid in 0.5-cc. portions until the liquid becomes no lighter in color. Cool and filter into a separatory funnel, washing with cold water. Extract four times with 25 cc. of chloroform. Evaporate the chloroform extract from a weighed flask with aid of an air blast and dry at 100 deg. C. to constant weight (one-half hour is usually sufficient). Weigh the residue as caffein and calculate on 7.5 grams of coffee. Test the purity of the residue by determining nitrogen and multiplying by 3.464 to obtain caffein.

15. Caffein--Power-Chestnut Method--Official

Moisten 10 grams of the finely powdered sample with alcohol, transfer to a Soxhlet, or similar extraction apparatus, and extract with alcohol for 8 hours. (Care should be exercised to assure complete extraction.) Transfer the extract with the aid of hot water to a porcelain dish containing 10 grams of heavy magnesium oxid in suspension in 100 cc. of water. (This reagent should meet the U.S.P. requirements.) Evaporate slowly on the steam bath with frequent stirring to a dry, powdery mass. Rub the residue with a pestle into a paste with boiling water. Transfer with hot water to a smooth filter, cleaning the dish with a rubber-tipped glass rod. Collect the filtrate in a liter flask marked at 250 cc. and wash with boiling water until the filtrate reaches the mark. Add 10 cc. of 10-percent sulphuric acid and boil gently for 30 minutes with a funnel in the neck of the flask. Cool and filter through a moistened double paper into a separatory funnel and wash with small portions of 0.5-percent sulphuric acid. Extract with six successive 25-cc. portions of chloroform. Wash the combined chloroform extracts in a separatory funnel with 5 cc. of 1-percent potassium hydroxid solution. Filter the chloroform into an Erlenmeyer flask. Wash the potassium hydroxid with 2 portions of chloroform of 10 cc. each, adding them to the flask together with the chloroform washings of the filter paper. Evaporate or distil on the steam bath to a small volume (10-15 cc.), transfer with chloroform to a tared beaker, evaporate carefully, dry for 30 minutes in a water oven, and weigh. The purity of the residue can be tested by determining nitrogen and multiplying by the factor 3.464.

16. Crude Fiber--Official

Prepare solutions of sulphuric acid and sodium hydroxid of exactly 1.25-percent strength, determined by titration. Extract a quantity of the substance representing about 2 grams of the dry material with ordinary ether, or use residue from the determination of the ether extract. To this residue in a 500-cc. flask add 200 cc. of boiling 1.25-percent sulphuric acid; connect the flask with a reflux condenser, the tube of which passes only a short distance beyond the rubber stopper into the flask, or simply cover a tall conical flask, which is well suited for this determination, with a watch glass or short stemmed funnel. Boil at once and continue boiling gently for thirty minutes. A blast of air conducted into the flask may serve to reduce the frothing of the liquid. Filter through linen, and wash with boiling water until the washings are no longer acid; rinse the substance back into the flask with 200 cc. of the boiling 1.25-percent solution of sodium hydroxid free, or nearly so, of sodium carbonate; boil at once and continue boiling gently for thirty minutes in the same manner as directed above for the treatment with acid. Filter at once rapidly, wash with boiling water until the washings are neutral. The last filtration may be performed upon a Gooch crucible, a linen filter, or a tared filter paper. If a linen filter is used, rinse the crude fiber, after washing is completed, into a flat-bottomed platinum dish by means of a jet of water; evaporate to dryness on a steam bath, dry to constant weight at 110 deg. C., weigh, incinerate completely, and weigh again. The loss in weight is considered to be crude fiber. If a tared filter paper is used, weigh in a weighing bottle. In any case, the crude fiber after drying to constant weight at 110 deg. C., must be incinerated and the amount of the ash deducted from the original weight.

17. Starch--Tentative

Extract 5 grams of the finely pulverized sample on a hardened filter with five successive portions (10 cc. each) of ether, wash with small portions of 95-percent alcohol by volume until a total of 200 cc. have passed through, place the residue in a beaker with 50 cc. of water, immerse the beaker in boiling water and stir constantly for 15 minutes or until all the starch is gelatinized; cool to 55 deg. C., add 20 cc. of malt extract and maintain at this temperature for an hour. Heat again to boiling for a few minutes, cool to 55 deg. C., add 20 cc. of malt extract and maintain at this temperature for an hour or until the residue treated with iodin shows no blue color upon microscopic examination. Cool, make up directly to 250 cc., and filter. Place 200 cc. of the filtrate in a flask with 20 cc. of hydrochloric acid (sp. gr. 1.125); connect with a reflux condenser and heat in a boiling water bath for 2.5 hours. Cool, nearly neutralize with sodium hydroxid solution, and make up to 500 cc. Mix the solution well, pour through a dry filter and determine the dextrose in an aliquot. Conduct a blank determination upon the same volume of the malt extract as used upon the sample, and correct the weight of reduced copper accordingly. The weight of the dextrose obtained multiplied by 0.90 gives the weight of starch.

18. Sugars--Tentative

See original.[186]

19. Petroleum Ether Extract--Official

Dry 2 grams of coffee at 100 deg. C., extract with petroleum ether (boiling point 35 deg. to 50 deg. C.) for 16 hours, evaporate the solvent, dry the residue at 100 deg. C., cool, and weigh.

20. Total Acidity--Tentative

Treat 10 grams of the sample, prepared as directed under 4, with 75 cc. of 80-percent alcohol by volume in an Erlenmeyer flask, stopper, and allow to stand 16 hours, shaking occasionally. Filter and transfer an aliquot of the filtrate (25 cc. in the case of green coffee, 10 cc. in the case of roasted coffee) to a beaker, dilute to about 100 cc. with water and titrate with N/10 alkali, using phenolphthalein as an indicator. Express the result as the number of cc. of N/10 alkali required to neutralize the acidity of 100 grams of the sample.

21. Volatile Acidity--Tentative

Into a volatile acid apparatus introduce a few glass beads, and over these place 20 grams of the unground sample. Add 100 cc. of recently boiled water to the sample, place a sufficient quantity of recently boiled water in the outer flask and distil until the distillate is no longer acid to litmus paper. Usually 100 cc. of distillate will be collected. Titrate the distillate with N/10 alkali, using phenolphthalein as an indicator. Express the result as the number of cc. of N/10 alkali required to neutralize the acidity of 100 grams of the sample.

UNOFFICIAL METHODS

22. Protein

Determine nitrogen in 3 grams of the sample by the Kjeldahl or Gunning method. This gives the total nitrogen due to both the proteids and the caffein. To obtain the protein nitrogen, subtract from the total nitrogen the nitrogen due to caffein, obtained by direct determination on the separated caffein or by calculation (caffein divided by 3.464 gives nitrogen). Multiply by 6.25 to obtain the amount of protein.

23. Ten Percent Extract--McGill Method

Weigh into a tared flask the equivalent of 10 grains of the dried substance, add water until the contents of the flask weigh 110 grams, connect with a reflux condenser and heat, beginning the boiling in 10 to 15 minutes. Boil for 1 hour, cool for 15 minutes, weigh again, making up any loss by the addition of water, filter, and take the specific gravity of the filtrate at 15 deg. C.

According to McGill, a 10-percent extract of pure coffee has a specific gravity of 1.00986 at 15 deg. C., and under the same treatment chicory gives an extract with a specific gravity of 1.02821. In mixtures of coffee and chicory the approximate percentage of chicory may be calculated by the following formula:

(1.02821 - sp. gr.) Percent of chicory = 100 ------------------ 0.01835

The index of refraction of the above solution may be taken with the Zeiss immersion refractometer or with the Abbe refractometer.

With a 10-percent coffee extract, n_d 20 deg. = 1.3377.

With a 10-percent chicory extract, n_d 20 deg. = 1.3448.

Determinations of the solids, ash, sugar, nitrogen, etc., may be made in the 10-percent extract, if desired.

24. Caffetannic Acid--Krug's Method[187]

Treat 2 grains of the coffee with 10 cc. of water and digest for 36 hours; add 25 cc. of 90-percent alcohol and digest 24 hours more, filter, and wash with 90-percent alcohol. The filtrate contains tannin, caffein, color, and fat. Heat the filtrate to the boiling point and add a saturated solution of lead acetate. If this is carefully done, a caffetannate of lead will be precipitated containing 49 percent of lead. As soon as the precipitate has become flocculent, collect on a tared filter, wash with 90-percent alcohol until free from lead, wash with ether, dry and weigh. The precipitate multiplied by 0.51597 gives the weight of the caffetannic acid.

XVIII. PHARMACOLOGY OF THE COFFEE DRINK

General physiological action--Effect on children--Effect on longevity--Behavior in the alimentary regime--Place in dietary--Action on bacteria--Use in medicine--Physiological action of "caffetannic acid"--Of caffeol--Of caffein--Effect of caffein on mental and motor efficiency--Conclusions

By Charles W. Trigg

Industrial Fellow of the Mellon Institute of Industrial Research, Pittsburgh, 1916-1920

The published information regarding the effects of coffee drinking on the human system is so contradictory in its nature that it is hazardous to make many generalizations about the physiological behavior of coffee. Most of the investigations that have been conducted to date have been characterized by incompleteness and a failure to be sufficiently comprehensive to eliminate the element of individual idiosyncrasy from the results obtained. Accordingly, it is possible to select statements from literature to the effect either that coffee is an "elixir of life," or even a poison.

This is a deplorable state of affairs, not calculated to promote the dissemination of accurate knowledge among the consuming public, but it may be partly excused upon the grounds that experimental apparatus has not always been at the level of perfection that it now occupies. Also, to do justice to some of the able men who have interested themselves in this problem, it should be said that some of their results were obtained in researches, distinguished by painstaking accuracy, which have effected the establishment of the major reactions of ingested coffee.

The Physiological Action of Coffee

Drinking of coffee by mankind may be attributed to three causes: the demand for, and the pleasing effects of, a hot drink (a very small percentage of the coffee consumed is taken cold), the pleasing reaction which its flavors excite on the gustatory nerve, and the stimulating effect which it has upon the body. The flavor is due largely to the volatile aromatic constituents, "caffeol," which, when isolated, have a general depressant action on the system; and the stimulation is caused by the caffein. The general and specific actions of these individual components, together with that of the hypothetical "caffetannic acid," are considered under separate headings.

Coffee may be considered a member of the general class of adjuvant, or auxiliary, foods to which other beverages and condiments of negligible inherent food value belong. Its position on the average menu may be attributed largely to its palatability and comforting effects. However, the medicinal value of coffee in the dietary and per se must not be overlooked.

The ingestion of coffee infusion is always followed by evidences of stimulation. It acts upon the nervous system as a powerful cerebro-spinal stimulant, increasing mental activity and quickening the power of perception, thus making the thoughts more precise and clear, and intellectual work easier without any evident subsequent depression. The muscles are caused to contract more vigorously, increasing their working power without there being any secondary reaction leading to a diminished capacity for work. Its action upon the circulation is somewhat antagonistic; for while it tends to increase the rate of the heart by acting directly on the heart muscle, it tends to decrease it by stimulating the inhibitory center in the medulla.[188]

The effect on the kidneys is more marked, the diuretic effect being shown by an increase in water, soluble solids, and of uric acid directly attributable to the caffein content of the coffee taken. In the alimentary tract coffee seems to stimulate the oxyntic cells and slightly to increase the secretion of hydrochloric acid, as well as to favor intestinal peristalsis. It is difficult to accept reports of coffee accomplishing both a decrease in metabolism and an increase in body heat; but if the production of heat by the demethylation of caffein to form uric acid and a possible repression of perspiration by coffee be considered, the simultaneous occurrence of these two physiological reactions may be credited.

The disagreement of medical authorities over the physiological effects of coffee is quite pronounced. This may be observed by a careful perusal of the following statements made by these men. It will be noticed that the majority opinion is that coffee in moderation is not harmful. Just how much coffee a person may drink, and still remain within the limits of moderation and temperance, is dependent solely upon the individual constitution, and should be decided from personal experience rather than by accepting an arbitrary standard set by some one who professes to be an authority on the matter.

A writer in the British Homeopathic Review[189] says that "the exciting effects of coffee upon the nervous system exhibit themselves in all its departments as a temporary exaltation. The emotions are raised in pitch, the fancies are lively and vivid, benevolence is excited, the religious sense is stimulated, there is great loquacity.... The intellectual powers are stimulated, both memory and judgment are rendered more keen and unusual vivacity of verbal expression rules for a short time." He continues:

Hahnemann gives a characteristically careful account of the coffee headache. If the quantity of coffee taken be immoderately great and the body be very excitable and quite unused to coffee, there occurs a semilateral headache from the upper part of the parietal bone to the base of the brain. The cerebral membranes of this side also seem to be painfully sensitive, the hands and feet becoming cold, and sweat appears on the brows and palms. The disposition becomes irritable and intolerant, anxiety, trembling and restlessness are apparent.... I have met with headaches of this type which yielded readily to coffee and with many more in which the indicated remedy failed to act until the use of coffee as a beverage was abandoned. The eyes and ears suffer alike from the super-excitation of coffee. There is a characteristic toothache associated with coffee.

In apparent contradiction of this opinion, Dr. Valentin Nalpasse,[190] of the Faculty of Medicine of Paris, states:

When coffee is properly made and taken in moderation, it is a most valuable drink. It facilitates the digestion because it produces a local excitement. Its principal action gives clear and stable imaginative power to the brain. By doing that, it makes intellectual work easy, and, to a certain extent, regulates the functions of the brain. The thoughts become more precise and clear, and mental combinations are formed with much greater rapidity. Under the influence of coffee, the memory is sometimes surprisingly active, and ideas and words flow with ease and elegance.... Many people abuse coffee without feeling any bad effect.

Discussing the use and abuse of coffee, I.N. Love[191] says:

The world has in the infusion of coffee one of its most valuable beverages. It is a prompt diffusible stimulant, antiseptic and encourager of elimination. In season it supports, tides over danger, helps the appropriate powers of the system, whips up the flagging energies, enhances the endurance; but it is in no sense a food, and for this reason it should be used temperately.

Also Dr. Jonathan Hutchinson[192] makes the following weighty pronouncement:

In reference to my suggestion to give children tea and coffee. I may explain that it is done advisedly. There is probably no objection to their use even at early ages. They arouse the dull, calm the excitable, prevent headaches, and fit the brain for work. They preserve the teeth, keep them tight in their place, strengthen the vocal chords, and prevent sore throat. To stigmatize these invaluable articles of diet as "nerve stimulants" is an erroneous expression, for they undoubtedly have a right to rank as nerve nutrients.

But Dr. Harvey Wiley[193] comes forth with evidence on the other side, saying:

The effects of the excessive use of coffee, tea, and other natural caffein beverages is well known. Although the caffein is combined in these beverages naturally, and they are as a rule taken at meal times, which mitigates the effects of the caffein, they are recognized by every one as tending to produce sleeplessness, and often indigestion, stomach disorders, and a condition which, for lack of a better term, is described as nervousness.... The excessive drinking of tea and coffee is acknowledged to be injurious by practically all specialists.

Dr. V.C. Vaughn,[194] of the University of Michigan, speaking of tea and coffee, expresses this opinion:

I believe that caffein used as a beverage and in moderation not only is harmless to the majority of adults, but is beneficial.

This verdict is upheld by the results of a symposium[195] conducted by the Medical Times, in which a large majority of the medical experts participating, among whom may be enumerated Drs. Lockwood, Wood, Hollingworth, Robinson, and Barnes, agreed that the drinking of coffee is not harmful per se, but that over-indulgence is the real cause of any ill effects. This is also true of any ingested material.

Insomnia is a condition frequently attributed to coffee, but that the authorities disagree on this ground is shown by Wiley's[196] contention, "We know beyond doubt that the caffein (in coffee) makes a direct attack on the nerves and causes insomnia." While Woods Hutchinson[197] observes:

Oddly enough, a cup of hot, weak tea or coffee, with plenty of cream and sugar, will often help you to sleep, for the grateful warmth and stimulus to the lining of the stomach, drawing the blood into it and away from the head, will produce more soothing effects than the small amount of caffein will produce stimulating and wakeful ones.

The writer has often had people remark to him that while black coffee sometimes kept them awake, coffee with cream or sugar or both made them drowsy.

In the course of experiments conducted by Montuori and Pollitzer[198] it was found that coffee prepared by hot infusion when given by mouth or hypodermically with the addition of a small dose of alcohol proved an efficient means of combating the pernicious effects of low temperatures. Coffee prepared by boiling, and tea, showed negative effects.

The value of coffee as a strength-conserver, and its function of increasing endurance, morale, and healthfulness, was demonstrated by the great stress which the military authorities, in the late and in previous wars, placed upon furnishing the soldiers with plenty of good coffee, particularly at times when they were under the greatest strain. Various articles[199] record this fact; and these statements are further borne out by the data given below in the discussion of the physiological effects of caffein, to which the majority of the stimulating effects of coffee may be attributed.

According to Fauvel,[200] with a healthy patient on a vegetable diet, chocolate and coffee increase the excretion of purins, diminishing the excretion of uric acid and apparently hindering the precipitation of uric acid in the organism. This diminution, however, was not due to retention of uric acid in the organism.

"Habit-forming" is one of the adjectives often used in describing coffee, but it is a fact that coffee is much less likely than alcoholic liquors to cause ill effects. A man rarely becomes a slave of coffee; and excessive drinking of this beverage never produces a state of moral irresponsibility or leads to the commission of crime. Dr. J.W. Mallet,[201] in testimony given before a Federal Court, stated that caffein and coffee were not habit-forming in the correct sense of the term. His definition of the expression is that the habit formed must be a detrimental and injurious one--one which becomes so firmly fixed upon a person forming it that it is thrown off with great difficulty and with considerable suffering, continuous exercise of the habit increasing the demand for the habit-forming drug. It is well known that the desire ceases in a very short period of time after cessation of use of caffein-containing beverages, so that in that sense, coffee is not habit-forming.

It has been shown by Gourewitsch[202] that the daily administration of coffee produces a certain degree of tolerance, and that the doses must be increased to obtain toxic results. Harkness[203] has been quoted as stating that "taken in moderation; coffee is one of the most wholesome beverages known. It assists digestion, exhilarates the spirits, and counteracts the tendency to sleep." Carl V. Voit,[204] the German physiological chemist, says this about coffee:

The effect of coffee is that we are bothered less by unpleasant experiences and become more able to conquer difficulties; therefore, for the feasting rich, it makes intestinal work after a meal less evident and drives away the deadly ennui; for the student it is a means to keep wide awake and fresh; for the worker it makes the day's fatigue more bearable.

Dr. Brady[205] believes that the so-called harmfulness of coffee is mainly psychological, as evidenced by his expression, "Most of the prejudice which exists against coffee as a beverage is based upon nothing more than morbid fancy. People of dyspeptic or neurotic temperament are fond of assuming that coffee must be bad because it is so good, and accordingly, denying themselves the pleasure of drinking it."

The recounting of evidence, both pro and con, relevant to the general effects of coffee could continue almost ad infinitum, but the fairest unification of the various opinions is best quoted from Woods Hutchinson[206]:

Somewhere from 1 to 3 percent of the community are distinctly injured or poisoned by tea or coffee, even small amounts producing burning of the stomach, palpitation of the heart, headache, eruptions of the skin, sensations of extreme nervousness, and so on; though the remaining 97 percent are not injured by them in any appreciable way if consumed in moderation.

So, if one is personally satisfied that he belongs to the abnormal minority, and has not been argued by fallacious reasoning into his belief that coffee injures him, he should either reduce his consumption of coffee or let it alone. Even those most vitally interested in the commercial side of coffee will admit that this is the logical procedure.

Effects of Coffee on Children

The same sort of controversy has raged around the question of the advisability of giving coffee to children as has occurred regarding its general action. Dr. J. Hutchinson[207] advocates furnishing children with coffee, while Dr. Charlotte Abbey[208] is strongly against such a practise, claiming that use of caffein-containing beverages before the attainment of full growth will weaken nerve power. Nalpasse[209] observes that until fully developed the young are immoderately excited by coffee; and Hawk[210] is of the opinion that to give such a stimulant to an active school-child is both logically and dietetically incorrect. Dr. Vaughn[211] advances this scientific argument against the drinking of coffee by children under seven years of age:

In proportion to body weight the young contain more of the xanthin bases than adults. They are already laden with these physiological stimulants, and the additional dose given in tea or coffee may be harmful.

In a study of the effects of coffee drinking upon 464 school children, C.K. Taylor[212] found a slight difference in mental ability and behavior, unfavorable to coffee. About 29 percent of these children drank no coffee; 46 percent drank a cup a day; 12 percent, 2 cups; 8 percent, 3 cups; and the remainder, 4 or more cups a day. The measurements of height, weight, and hand strength also showed a slight advantage in favor of the non-coffee drinkers. If these results be taken as truly representative, their indication is obvious. However, it seems desirable to repeat these experiments upon other groups; at the same time noting carefully the factors of environment, and other diet, before any criterion is made.

As a refutation to this experimental evidence is the practical experience of the inhabitants of the Island of Groix, off the Brittany coast, whose annual consumption of coffee is nearly 30 pounds per capita, being ingested both as the roasted bean and as an infusion. It is reported that many of the children are nourished almost entirely on coffee soup up to ten years of age, yet the mentality and physique of the populace does not fall below that of others of the same stock and educational opportunities.[213]

Pertinent in this connection is Hawk's[214] statement that young mothers should refrain from the use of coffee, as caffein stimulates the action of the kidneys and tends to bring about a loss from the body of some of the salts necessary to the development of the unborn child as well as for the proper production of milk during the nursing period. The caffein of coffee also increases the flow of milk, but the milk produced is correspondingly dilute and a later decreased secretion may be expected. Furthermore, some of the caffein of the coffee may pass into the mother's milk, thus reaching the child, so that the use of coffee during the nursing period is undesirable on this ground also. Naturally, the question arises as to whether this arraignment is purely theoretical or based upon analytical and clinical data.

It is a difficult matter definitely to set an age below which coffee should not be drunk, as the time of reaching maturity varies with climate and ancestral origin. Yet, from a theoretical standpoint, children before or during the adolescent period should be limited to the use of a rather small amount of tea and coffee as beverages, as their poise and nerve control have not reached a stage of development sufficient to warrant the stimulation incident to the consumption of an appreciable quantity of caffein.

Coffee Drinking and Longevity

There are many who would have us believe that the use of coffee is only a means toward the end of quickly reaching the great beyond; but it is known that the habitual coffee drinker generally enjoys good health, and some of the longest-lived people have used it from their earliest youth without any apparent injury to their health. Nearly every one has an acquaintance who has lived to a ripe old age despite the use of coffee. Quoting Metchnikoff[215]:

In some cases centenarians have been much addicted to the drinking of coffee. The reader will recall Voltaire's reply when his doctor described the grave harm that comes from the abuse of coffee, which acts as a real poison. "Well", said Voltaire, "I have been poisoning myself for nearly eighty years." There are centenarians who have lived longer than Voltaire and have drunk still more coffee. Elizabeth Durieux, a native of Savoy, reached the age of 114. Her principal food was coffee, of which she took daily as many as forty small cups. She was jovial and a boon table companion, and used black coffee in quantities that would have surprised an Arab. Her coffee-pot was always on the fire, like the tea-pot in an English cottage (Lejoncourt, p. 84; Chemin, p. 147).

The entire matter resolves itself into one of individual tolerance, resistivity, and constitution. Numerous examples of young abstainers who have died and coffee drinkers who have still lived on can be found, and vice versa, the preponderance of instances being in neither direction. Bodies of persons killed by accident have been painstakingly examined for physiological changes attributable to coffee; but no difference between those of coffee and of non-coffee drinkers (ascertained by careful investigation of their life history) could be discerned.[216] In the long run, it is safe to say that the effect of coffee drinking upon the prolongation or shortening of life is neutral.

Coffee in the Alimentary Tract

When coffee is taken per os it passes directly to the stomach, where its sole immediate action is to dilute the previous contents, just as other ingested liquids do. Eventually the caffein content is absorbed by the system, and from thence on a stimulation is apparent. Considerable conjecture has occurred over the difference in the effects of tea and coffee, the most feasible explanation advanced being one appearing in the London Lancet.[217]

The caffein tannate of tea is precipitated by weak acids, and the presumption is that it is precipitated by the gastric juice and, therefore, the caffein is probably not absorbed until it reaches the alkaline alimentary tract. In the case of coffee, however, in whatever form the caffein may be present, it is soluble in both alkaline and acid fluids, and, therefore, the absorption of the alkaloid probably takes place in the stomach.

This theory, if true, goes far toward explaining the more rapid stimulation of coffee.

The statement has sometimes been made that milk or cream causes the coffee liquid to become coagulated when it comes into contact with the acids of the stomach. This is true, but does not carry with it the inference that indigestibility accompanies this coagulation. Milk and cream, upon reaching the stomach, are coagulated by the gastric juice; but the casein product formed is not indigestible. These liquids, when added to coffee, are partially acted upon by the small acid content of the brew, so that the gastric juice action is not so pronounced, for the coagulation was started before ingestion, and the coagulable constituent, casein, is more dilute in the cup as consumed than it is in milk. Accordingly, the particles formed by it in the stomach will be relatively smaller and more quickly and easily digested than milk per se. It has been observed that coffee containing milk or cream is not as stimulating as black coffee. The writer believes that this is probably due to mechanical inclusion of caffein in the casein and fat particles, and also to some adsorption of the alkaloid by them. This would materially retard the absorption of the caffein by the body, spread the action over a longer period of time, and hence decrease the maximum stimulation attained.

In a few instances, a small fraction of one percent of coffee users, there is a certain type of distress, localized chiefly in the alimentary tract, caused by coffee, which can not be blamed upon the much-maligned caffein. The irritating elements may be generally classified as compounds formed upon the addition of cream or milk to the coffee liquor, volatile constituents, and products formed by hydrolysis of the fibrous part of the grounds. It may be generally postulated that the main causation of this discomfort is due to substances formed in the incorrect brewing of coffee, the effect of which is accentuated by the addition of cream or milk, when the condition of individual idiosyncrasy is present.

Without enlarging upon his reason, Lorand[218] concludes that neither tea nor coffee is advisable for weak stomachs. Nalpasse,[219] however, believes that coffee taken after meals makes the digestion more perfect and more rapid, augmenting the secretions, and that it agrees equally well with people inclined to embonpoint and heavy eaters whose digestion is slow and difficult. Thompson[220] also observes that coffee drunk in moderation is a mild stimulant to gastric digestion.

Eder[221] reported, as the result of an inquiry into the action of coffee on the activity of the stomachs of ruminants, that coffee infusions produced a transitory increase in the number and intensity of the movements of the paunch, but that the influence exercised was very irregular.

An elaborate investigation of the action of tea and coffee on digestion in the stomach was made by Fraser,[222] in which he found that both retard peptic digestion, the former to a greater degree than the latter. The digestion of white of egg, ham, salt beef, and roast beef was much less affected than that of lamb, fowl, or bread. Coffee seemed actually to aid the digestion of egg and ham. He attributed the retarding effect to the tannic acid of the tea and the volatile constituents of the coffee--the caffein itself favoring digestion rather than otherwise. Tea increased the production of gas in all but salt foods, whereas coffee did not. Coffee is, therefore, to be preferred in cases of flatulent dyspepsia.

Hutchinson, in his Food and Dietetics, opines:

As regards the practical inferences to be drawn from experiences and observations, it may be said that in health the disturbance of digestion produced by the infused beverages (tea and coffee) is negligible. Roberts, indeed, goes so far as to suggest that the slight slowing of digestion which they produce may be favored rather than otherwise, as tending to compensate for too rapid digestibility which refinements of manufacture and preparation have made characteristic of modern foods.

Regarding increase in secretory activity, Moore and Allanston[223] report that in their experience meat extracts, tea, caffein solution, and coffee call forth a greater gastric secretion than does water, while with milk the flow of gastric juice seems to be retarded. Cushing[224] and others support this statement. This action is partially explained by Voit on the grounds that all tasty foods increase gastric secretion, the action being partly psychological; but Cushing observed the same effects upon introducing coffee directly into the stomachs of animals.

In general, a moderate amount of coffee stimulates appetite, improves digestion and relieves the sense of plenitude in the stomach. It increases intestinal peristalsis, acts as a mild laxative, and slightly stimulates secretion of bile. Excessive use, however, profoundly disturbs digestive function, and promotes constipation and hemorrhoids.[225] There is much evidence to support the view that "neither tea, coffee, nor chicory in dilute solutions has any deleterious action on the digestive ferments, although in strong solutions such an action may be manifest."[226] After conducting exhaustive experiments with various types of coffee, Lehmann[227] concluded that ordinary coffee is without effect on the digestion of the majority of sound persons, and may be used with impunity.

Coffee in the Dietary--Food Value

There are three things to be considered in deciding upon the inclusion of a substance in the dietary--palatability, digestibility without toxicity or disarrangement, and calorific value. Coffee is as satisfactory from these viewpoints as any other food product.

The palatability of a well-made cup of good coffee needs no eulogizing; it speaks for itself. It adds enormously to the attractiveness of the meal, and to our ability to eat with relish and appetite large amounts of solid foods, without a subsequent uncomfortable feeling. Wiley[228] says that the feeling of drowsiness after a full meal is a natural condition incidental to the proper conduct of digestion, and that to drive away this natural feeling with coffee must be an interference with the normal condition. However, if by so doing, we can increase our over-all efficiency without material harm to our digestive organs (and we can and do), the procedure has much in its favor both psychologically and dietetically.

The fact that coffee favors digestion without eventual disarrangement has been demonstrated above. On the subject of the relative agreement with the constitution of foods of daily consumption, Dr. English[229] said:

It is well known that there is no species of diet which invariably suits all constitutions, nor will that which is palatable and salutary at one time be equally palatable and salutary at another time to the same individual. I think the most natural food provided for us is milk; yet I will engage to show twenty instances where milk disagrees more than coffee.

Further in this regard, Hutchinson[230] considers that ninety percent of the "dyspepsias" attributed to coffee are due to malnutrition, or to food simultaneously ingested, no disease known to the medical profession being directly attributable to it.

No one cognizant of the facts will contend that a cup of black coffee has any direct food value; but not so with the roasted bean. This has quite an appreciable content of protein and fat, both substances of high calorific value. The inhabitants of the Island of Groix eat the whole roasted coffee bean in considerable quantity, and seem to obtain considerable nourishment therefrom. Also, the Galla, a wandering tribe of Africa, make large use of food balls, about the size of billiard balls, consisting of pulverized coffee held in shape with fat. One ball is said to contain a day's ration; and, because of its food content and stimulating power, serves to sustain them on long marches of days' duration.

When an infusion, or decoction, of roasted coffee is made, about 1.25 percent of the extracted matter is protein, it being accompanied by traces of dextrin and sugar. The same dearth of extraction of food materials occurs upon infusing coffee substitutes. This small amount can have but little dietetic significance. However, upon addition of sugar and of milk or cream, with their content of protein, fat, and lactose, the calorific value of the cup of coffee rises. Lusk and Gephart[231] give the food value of an ordinary restaurant cup of coffee as 195.5 calories, and Locke[232] gives it as 156.

Mattei[233] found that 8 cc. of an infusion of roasted Mocha coffee of five-percent strength suppressed incipient polyneuritis in pigeons within a few hours' time. Their weight did not improve, but otherwise they were completely restored to health. However, in from four to six weeks after the apparent cure, the symptoms rapidly returned and the pigeons perished, with symptoms of paralysis and cerebral complications. The temporary cure was probably due to caffein stimulation and secondary actions of the volatile constituents of coffee, which may be related to the vitamines; for it is not likely that the vitamines would withstand the heat of roasting. If B-vitamine does occur in roasted coffee, it is present only in traces.[234]

The inclusion of coffee in the average dietary is warranted because of its evident worth as an aid to digestion and for its assimilating power, thus earning its characterization as an "adjuvant food."

Action of Coffee on Bacteria

The employment of coffee as an aid to sanitation has been but little considered. Coffee, when freshly roasted and ground, is deodorant, antiseptic, and germicidal, probably due to the empyreumatic products developed during the process of roasting. An infusion of 0.5 percent inhibits the growth of many pathogenic organisms, and those of 10 percent kill anthrax bacteria in three hours, cholera spirilla in four hours, and many other bacteria, including those producing typhoid, in two to six days.[235]

The maintenance of a low rate of contraction of typhoid fever has often been attributed to drinking of coffee instead of water, the action of the coffee being partly due to the bactericidal effect of the caffeol and partly to the boiling of the water before infusion. The stimulating tendency of the caffein to sustain and to "tide over" those of low vitalities is also evidenced.

Use of Coffee in Medicine

Coffee has been employed in medicinal practise as a direct specific, as a preventive, and as an antidote. The United States Dispensatory[236] summarizes the uses of caffein and coffee as follows:

Caffein is a valuable remedy in practical medicine as a cerebral and cardiac stimulant and as a diuretic. In undue somnolence, in nervous headache, in narcotism, also, at times when the exigencies of life require excessively prolonged wakefulness, caffein may be used as the most powerful agent known for producing wakefulness. In a series of experiments, J. Hughes Bennett found that within narrow limits there is a direct physiological antagonism between caffein and morphine. Coffee and caffein in narcotic poisoning are of value as a means of keeping the patient awake, and of stimulating the respiratory centres.

As a cardiac stimulant, caffein may be used in any form of heart failure; the indications for its use are those which call for the employment of digitalis. It is superior to digitalis in never disagreeing with the stomach, in having no distinctive cumulative tendency, and in the promptness of its action. It is pronouncedly inferior to digitalis in the power and certainty of its action, and in the permanence of its influence once asserted. As a diuretic it is superior; it is very valuable in the treatment of cardiac dropsies, and is often useful in chronic Bright's disease when there is no irritation of the kidneys.

On account of its tendency to produce wakefulness, it is usually better to mass the doses early in the day, at least six hours being left between the last dose and the ordinary time for sleep. From eight to fifteen grams (of caffein) may be given in the course of a day in severe cases. If tried, it would probably prove a useful drug in cases of sudden collapse from various causes.

Good effects of coffee are recounted by Thompson.[237]

It removes the sensation of fatigue in the muscles, and increases their functional activity; it allays hunger to a limited extent; it strengthens the heart action; it acts as a diuretic, and increases the excretion of urea; it has a mildly sudorific influence; it counteracts nervous exhaustion and stimulates nerve centers. It is used sometimes as a nervine in cases of migraine, and there are many persons who can sustain prolonged mental fatigue and strain from anxiety and worry much better by the use of strong black coffee. In low delirium, or when the nervous system is overcome by the use of narcotics or by excessive hemorrhage, strong black coffee is serviceable to keep the patient from falling into the drowsiness which soon merges into coma. In such cases as much as half a pint of strong black coffee may be injected into the rectum.

Strong coffee with a little lemon juice or brandy is often useful in overcoming a malarial chill or a paroxysm of asthma. It is a useful temporary cardiac stimulant for children suffering collapse.

Dr. Restrepo,[238] of Medellin, Colombia, claims to have cured many cases of chronic malaria and related diseases with infusion of green coffee, after quinine had failed. Wallace[239] states that tincture of green coffee is a natural and efficacious specific for cholera, and that she knows of more than a thousand eases of cholera and diarrhea which have been treated with it without an isolated case of failure. Landanabileo has been quoted as using raw coffee infusion in hepatic and nephritic diseases, venal and hepatic colics, and in diabetes.

In the Civil War, surgeons utilized coffee in allaying malarial fever and other maladies with which they had to contend, often under the most trying conditions, and with severely limited means of combating disease.[240] Its effect is to counteract the depressant action of low and miasmatic atmospheres, opening the secretions which they have checked. Travelers from the colder climes soon find that the fragrant cup of coffee is a corrective to derangements of the liver resulting from climatic conditions.[241]

Dr. Guillasse, of the French Navy, in a paper on typhoid fever, says:

Coffee has given us unhoped for satisfaction, and after having dispensed it we find, to our great surprise, that its action is as prompt as it is decisive. No sooner have our patients taken a few tablespoonfuls of it, than their features become relaxed and they come to their senses. The next day the improvement is such that we are tempted to look upon coffee as a specific against typhoid fever. Under its influence the stupor is dispelled, and the patient arouses from the state of somnolency in which he has been since the invasion of the disease. Soon all the functions take their natural course, and he enters upon convalescence.[242]

Also it has been reported that in extreme cases of yellow fever, coffee has been used most effectively by many physicians as the main reliance after all other well known remedies have been administered and failed.

According to Lorand,[243] the use of coffee in gout is strictly prohibited by Umber and Schittenhelm; but he considered it a mistake absolutely to forbid coffee, as, when a person has good kidneys, the small amount of uric acid furnished by the caffein can readily be eliminated. A curious remedy for gout and rheumatism, the efficacy of which the writer scouts, is said to be[244]--a pint of hot, strong, black coffee, which must be perfectly pure, and seasoned with a teaspoonful of pure black pepper, thoroughly mixed before drinking, and the preparation taken just before going to bed. If this has any value, it is probably purely psychological in its function.

Several writers[245] attribute amblyopia and other affections of the sight to coffee and chicory, without giving much conclusive experimental data. Beer,[246] a Vienna oculist, however, held that the vapor from pure, hot, freshly-made coffee is beneficial to the eyes.

Coffee and caffein are physiologically antagonistic to the common narcotics, nicotine, morphine, opium, alcohol, etc., and are frequently used as antidotes for these poisons. Binz found that dogs that have been stupified with alcohol could be awakened with coffee. It may thus be prescribed for hard drinkers to counteract the baleful excitability produced by alcohol; in fact, many topers taper off after a long debauch with coffee containing small amounts of alcoholic beverages. Considering its ability to counteract the slow intoxication of tobacco, it may be inferred that coffee is indispensable for hard smokers.

In general, the medicinal value of coffee may be said to be directly attributable to its caffein content, although its antiseptic properties are dependent upon the volatile aromatic constituents. Its function is to raise and to sustain vitalities which have been lowered by disease or drugs. Although some of the cures attributed to it are probably purely traditional; still, it must be admitted, that by utilizing its stimulating qualities in many illnesses the patient may be carried past the danger point into convalescence.

Physiological Action of "Caffetannic Acid"

It has been demonstrated in chapter XVII that there is no definite compound "caffetannic acid," and that the heterogeneous material designated by this name does not possess the properties of tanning. Further substantiation of this contention, and more evidence of the innocuous character of the tannin-like compounds in coffee, are contained in the testimony of Sollmann.[247] "Tannins precipitate proteins, gelatine, and connective tissue, and thus act as astringents, styptics, and antiseptics. The different tannins are not equivalent in these respects. Some (which are perhaps misnamed) such as those of coffee and ipecac, are practically non-precipitant.... On the whole, one may say that the small quantities of tannin ordinarily taken with the food and drink are not injurious, but that large quantities (excessive tea drinking) are certainly deleterious. The tannin of coffee is scarcely astringent, and, therefore, lacks this action," which is proven by the fact that it does not precipitate proteins.

"It has been claimed that 'caffetannic acid' injures the stomach walls, but there is no evidence that this is so."[248] Wiley,[249] in reporting some of his experiments, says: "Apparently the efforts to saddle the injurious effects of coffee-drinking upon caffetannic acid in any form in which it may exist in the coffee-extract are not supported by these recent data." The fact that tannins retard intestinal peristalsis, whereas coffee promotes this digestive action, lends further proof to the non-existence of tannin in coffee. These statements by eminent authorities may be consolidated into the verity that there is no tannin, in the true sense of the term, in coffee; and that the constituents of the coffee brew which have been so designated are physiologically harmless.

Physiological Action of Caffeol

The evidence regarding the physiological action of caffeol is contradictory in many cases. J. Lehmann found in 1853, that the "empyreumatic oil of coffee, caffeone," is active; but more recent investigations have yielded results at variance with this. Hare and Marshall[250] believe that they proved it to be active. E.T. Reichert,[251] however, found it inactive in dogs, excepting in so far that, when given intravenously, it mechanically interfered with the circulation. With it Binz[252] was able to produce in man only feeble nervous excitement, with restlessness and increase in the rate and depth of respirations.

The general effects, as summated by Sollmann[253] are, for small doses, pleasant stimulation; increased respiration; increased heart rate, but fall of blood pressure; muscular restlessness; insomnia; perspiration; congestion; for large doses, increased peristalsis and defecation; depression of respiration and heart; fall of blood pressure and temperature; paralytic phenomena. It is doubtful whether the quantities taken in the beverage cause any direct central stimulation.

Investigations have also been conducted with the various known constituents of this "coffee oil." Erdmann[254] found that in doses of between 0.5 and 0.6 gram per kilo of body weight, furane-alcohol kills a rabbit by respiratory paralysis; and that the symptoms of poisoning are a short primary excitement, salivation, diarrhea, respiratory depression, continuous fall of the body temperature, and death from collapse with respiratory failure. In man, doses of from 0.6 to 1 gram of furane-alcohol increased respiratory activity without producing other symptoms.

However, man is not as susceptible to these compounds as are the smaller animals. But even if their relative susceptibility be assumed to be the same, the lethal dose given the rabbit is equivalent to giving a 140-pound man one dose containing the furane-alcohol content of over 5,000 cups of coffee. Thus, in view of the very apparent minuteness of the quantity of this compound present in one cup of coffee, together with the fact that it is not cumulative in its physiological action, the importance of its toxic properties becomes very inconsequential to even the most profuse and inveterate coffee drinkers.

Burmann[255] reported the volatile principle to have a reducing action on the hemoglobin; a depressing effect on the blood pressure; a depressant action on the central nervous system, disturbing the cardiac rhythm; and an action on the respiratory centers, causing dyspnea. The report of Sayre[256] regarding the minimum lethal dose of the concentrated combined active principles of coffee obtained from dry distillation is, for frogs, administered intraperitoneally and subcutaneously, 0.03 cubic centimeters per gram of body weight; for guinea pigs per stomach, 7.0 cc. per kilogram of body weight, and administered intravenously and intraperitoneally, about 1.0 cc. per kilogram.

This evidence regarding the physiological action of caffeol can not in any wise be construed to indicate a harmfulness of coffee. The percentage of these volatile substances in a cup of coffee infusion is so low as to be relatively negligible in its action. And, again, the caffein content of the brew, as will be seen, tends to counteract any possible desultory effects of the caffeol.

General Physiological Action of Caffein

More attention has been given to the study of the physiological action of caffein than to that of the other individual constituents of coffee. Since certain of the effects of coffee drinking have been attributed to this alkaloid, a brief presentment of the pharmacology of caffein will be given as an exposition of the many statements made regarding it. According to the British Pharmaceutical Codex[257]:

Caffein exerts three important actions: (1) on the central nervous system: (2) on muscles, including cardiac: and (3) on the kidney. The action on the central nervous system is mainly on that part of the brain connected with psychical functions. It produces a condition of wakefulness and increased mental activity. The interpretation of sensory impressions is more perfect and correct, and thought becomes clearer and quicker. With larger doses of caffein the action extends from the psychical areas to the motor area and to the cord, and the patient becomes at first restless and noisy, and later may show convulsive movements.

Caffein facilitates the performance of all forms of physical work, and actually increases the total work which can be obtained from muscle. On the normal man, however, it is impossible to say how much of the action on the muscle is central and how much peripheral, but, as fatigue shows itself first by an action on the center, it is probable that the action of caffein in diminishing fatigue is mainly central. Caffein accelerates the pulse and slightly raises blood pressure. It has no action in any way resembling digitalis; by increasing the irritability of the cardiac muscle, its prolonged use rather tends to fatigue than to rest the heart.

Caffein and its allies form a very important group of diuretics. The urine is generally of a lower specific gravity than normal, since it contains a lesser proportion of salt and urea; but the total excretion of solids, both as regards urea, uric acid, and salts, is increased. Caffein, by exciting the medulla, produces an initial vaso-constriction of the kidneys, which tends at first to retard the flow of urine. So in recent years, other drugs have been introduced, allies of caffein, which act like it on the kidneys, but are without the stimulant action on the brain. Theobromine is such a drug.

Another authority states that[258]:

One of the most constant symptoms produced in man by over-doses of caffein is excessive diuresis, and experiments made upon the lower animals show that caffein acts as a diuretic not only by influencing the circulation, but also by directly affecting the secreting cells, the probabilities being in favor of the first of these theories of action. According to Schroeder, not only the water but also the solids of the urine are increased.

The question whether caffein has an influence upon tissue changes and the consequent nitrogenous elimination can not be considered as distinctly answered, though the most probable conclusion is that the action of caffein upon urea elimination and upon general nutrition is not direct or pronounced. While the therapeutic dose of caffein is broken up in the body with the formation of methylxanthin, which escapes with the urine, the toxic dose is at least in part eliminated by the kidney unchanged.

The metabolism of the methyl purins, of which group caffein is a member, appears to vary with the quantity ingested. The manner in which the methyl group is liberated by the cell protoplasm is said[259] to determine the amount of stimulus which the tissues receive from these substances. The xanthin group is almost without any excitatory action, and its metabolic end products are constant. Perhaps the variation in the excretions of unchanged methylpurins is dependent upon the amount of total reactive energy they invoke.

Baldi[260] found that caffein in small doses increases muscular excitability in dogs and frogs. The spinal and muscular hyperic excitability produced by caffein is, in his opinion, due to the methyl groups attached to the xanthin nucleus. Fredericq[261] states that caffein increases the irritability of the cardiac vagus and accelerates the appearance of pseudofatigue of the vagus which is produced by prolonged stimulation of the nerve. The action of caffein on the mammalian heart has also been investigated by Pilcher,[262] who found that, following the rapid intravenous injection of caffein, there is an acute fall of blood pressure; and with a maximal quantity of caffein, 10 milligrams per kilogram, the cardiac volume and the amplitude of the excursions are usually unchanged. With larger quantities, the volume progressively increases and the amplitude of the excursion decreases.

Salant[263] found that the intravenous injection of 15 to 25 milligrams of caffein per kilogram in animals was followed by a fall of blood pressure amounting to 7 to 35 percent in most cases, which was transitory, although in some animals it remained unchanged. A moderate rise was rarely observed. Caffein aids the action of nitrates, acetanilid, ethyl alcohol and amyl alcohol, and increases the toxicity of barium chloride. In a very thorough study of the toxicity of caffein which he made with Reiger,[264] a greater toxicity of about 15 to 20 percent by subcutaneous injection than by mouth, and but about one-half this when injected peritoneally, was found. Intramuscularly the toxicity is 30 percent greater than subcutaneously. In making the tests on animals, they found that individuality, season, age, species, and certain pathological conditions caused variation in the toxic effect of the administered caffein. Low protein diet tends to decrease resistance to caffein in dogs, and a milk or meat diet does the same for growing dogs. Caffein is not cumulative for the rabbit or dog.

As a result of experiments on the action of caffein on the bronchiospasm caused by peptone (Witte), silk peptone, B-imidoazolyl-ethylamin, curare, vasodilation, and mucarin, Pal[265] concluded that caffein stimulates certain branches of the peripheral sympathetic and is thus enabled to widen the bronchi or remove bronchiospasm.

According to Lapicque[266], caffein produces a change in the excitability of the medulla of the frog similar to that produced by raising the temperature of the nerve centers. Schuerhoff[267] has pointed out that the continued use of large quantities of caffein will produce cardiac irregularity and sleeplessness.

Cochrane[268] cited three cases where caffein was hypodermically administered in cases of acute indigestion, etc., and concluded that the cases prove that caffein, or a compound containing it as a synergist, does indirectly make the injection of morphia a safe proceeding, and directly increases the force of the heart and arterial tension. However, Wood[269] found that medium doses of caffein do not produce any marked rise in blood pressure, and cause a reduction in pulse rate. He attributes the contradictory results which prior investigations gave, to employment of unusually large doses and to inaccurate experimental methods.

Caffein was found by Nonnenbruch and Szyszka[270] to have a slight action toward accelerating the coagulation time of the blood, being active over several hours. It inhibits coagulation in vitrio. Its action in the body apparently rests on an increase of the fibrin ferment. There is no reason to believe that the behavior is dependent on a toxic action, but there is probably an action on the spleen; for in several rabbits from which the spleen was removed, no action was observed.

Experiments conducted by Levinthal[271] gave no positive information as to the formation of uric acid from caffein in the human organism. The elimination of caffein has also been studied by Salant and Reiger[272], who found that larger amounts of caffein are demethylated in carnivora than in herbivora, and resistance to caffein is inversely as demethylation, caffein being much more toxic in the former class. In a similar investigation, Zenetz[273] observed that caffein is very slightly eliminated from the system by the kidneys, and that its action on the heart is cumulative; therefore he concludes that it is contra-indicated in all renal diseases, in arterio-sclerosis, and in cardiac affections secondary to them. The inaccuracy of these conclusions regarding the non-elimination of caffein and those of Albanese,[274] Bondzynski and Gottlieb[275], Leven[276], Schurtzkwer[277], and Minkowski[278], has been shown by Mendel and Wardell[279], who point out that many of these experimenters worked with dogs, in which the chief end-product of purin metabolism is not uric acid, but allantoin. They observe that the increase in excretion of uric acid after the addition of caffein to the diet seems to be proportional to the quantity of caffein taken, and equivalent to from 10 to 15 percent of the ingested caffein. The remainder of the caffein is probably eliminated as mono-methylpurins.

Regarding the alleged cumulative action of caffein, Pletzer[280], Liebreich,[281] Szekacs[282], Pawinski,[283] and Seifert[284] all concluded from their investigations that the action of caffein is usually of brief duration, and does not have a cumulative effect, because of its rapid elimination; so that there is no danger of intoxication.

Dr. Oswald Schmiedeberg says:

Caffein is a means of refreshing bodily and mental activity, so that this may be prolonged when the condition of fatigue has already begun to produce restraint, and to call for more severe exertion of the will, a state which, as is well known, is painful or disagreeable.

This advantageous effect, in conditions of fatigue, of small quantities of caffein, as it is commonly taken in coffee or tea, might, however, by continued use become injurious, if it were in all cases necessarily exerted; that is to say, if by caffein the muscles and nerves were directly spurred on to increased activity. This is not the case, however, and just in this lies the peculiarity of the effect in question. The muscles and the simultaneously-acting nerves only under the influence of caffein respond more easily to the impulse of the will, but do not develop spontaneous activity; that is, without the co-operation of the will.

The character of caffein action makes plain that these food materials do not injure the organism by their caffein content, and do not by continued use cause any chronic form of illness.

According to Dr. Hollingworth's[285] deductions, caffein is the only known stimulant that quickens the functions of the human body without a subsequent period of depression. His explanation for this behavior is that "caffein acts as a lubricator for the nervous system, having an actual physical action whereby the nerves are enabled to do their work more easily. Other stimulants act on the nerves themselves, causing a waste of energy, and consequently, according to nature's law, a period of depression follows, and the whole process tends to injure the human machine." In not a single instance during his experiments at Columbia University did depression follow the use of caffein.

Of course, caffein, like any other alkaloid, if used to excess will prove harmful, due to the over-stimulation induced by it. However, taken in moderate quantities, as in coffee and tea by normal persons, the conclusions of Hirsch[286] may be taken as correct, namely: caffein is a mild stimulant, without direct effect on the muscles, the effect resulting from its own destruction and being temporary and transitory; it is not a depressant either initially or eventually; and is not habit-forming but a true stimulant, as distinguished from sedatives and habit-forming drugs.

Caffein and Mental and Motor Efficiency

The literature on the influence of caffein on fatigue has been summarized, and the older experiments clearly pointed out, by Rivers[287]. A summary of the most important researches which have had as their object the determination of the influence of caffein on mental and motor processes has been made by Hollingworth[288], from whose monograph much of the following material has been taken.

Increase in the force of muscular contractions was demonstrated in 1892 by De Sarlo and Barnardini[289] for caffein and by Kraepelin for tea. These investigators used the dynamometer as a measure of the force of contraction; however, most of the subsequent work on motor processes has been by the ergographic method. Ugolino Mosso[290], Koch[291]. Rossi[292], Sobieranski[293], Hoch and Kraepelin,[294] Destree,[295] Benedicenti,[296] Schumberg,[297] Hellsten,[298] and Joteyko,[299] have all observed a stimulating effect of caffein on ergographic performance. Only one investigation of those reported by Rivers failed to find an appreciable effect, that of Oseretzkowsky and Kraepelin,[300] while Fere[301] affirms that the effect is only an acceleration of fatigue.

In spite of the general agreement as to the presence of stimulation there is some dissension regarding whether only the height of the contractions or their number or both are affected. As might be expected from the great diversity of methods employed, the quantitative results also have varied considerably. Carefully controlled experiments by Rivers and Webber[302] "confirm in general the conclusion reached by all previous workers that caffein stimulates the capacity for muscular work; and it is clear that this increase is not due to the various psychical factors of interest, sensory stimulation, and suggestion, which the experiments were especially designed to exclude. The greatest increase ... falls, however, far short of that described by some previous workers, such as Mosso; and it is probable that part of the effect described by these workers was due to the factors in question."

Investigations of mental processes under the influence of caffein have been much less frequent, most notable among which are those of Dietl and Vintschgau,[303] Dehio,[304] Kraepelin and Hoch,[305] Ach,[306] Langfeld,[307] and Rivers.[308] Kraepelin[309] observes: "We know that tea and coffee increase our mental efficiency in a definite way, and we use these as a means of overcoming mental fatigue ... In the morning these drinks remove the last traces of sleepiness and in the evening when we still have intellectual tasks to dispose of they aid in keeping us awake." Their use induces a greater briskness and clearness of thought, after which secondary fatigue is either entirely absent or is very slight.

Tendency toward habituation of the pyschic functions to caffein has been studied by Wedemeyer[310], who found that in the regular administration of it in the course of four to five weeks there is a measurable weakening of its action on psychic processes.

Rivers[311], who seems to have been the first to appreciate fully the genuine and practical importance of thoroughly controlling the psychological factors that are likely to play a role in such experiments, concludes that "caffein increases the capacity for both muscular and mental work, this stimulating action persisting for a considerable time after the substance has been taken without there being any evidence, with moderate doses, of reaction leading to diminished capacity for work, the substance thus really diminishing and not merely obscuring the effects of fatigue."

EFFECT OF CAFFEIN ON MENTAL AND MOTOR PROCESSES

Schematic Summary of All Results

St.=Stimulation. 0=No effect. Ret.=Retardation.

PRIMARY EFFECT Small Doses | Medium Doses | | Large Doses | | | Secondary Reaction | | | | Action Time Hrs. | | | | | Duration | | | | | in Hrs. Process Tests | | | | | | Motor speed 1. Tapping St. St. St. None .75-1.5 2-4 Coordination 2. Three-hole St. 0 Ret. None 1-1.5 3-4 3. Typewriting (a) Speed St. 0 Ret. None Results show (b) Errors Fewer for all None only in total doses days' work Association 4. Color-naming St. St. St. None 2-2.5 3-4 5. Opposites St. St. St. None 2.5-3 Next day 6. Calculation St. St. St. None 2.5 Next day Choice 7. Discrimination reaction time Ret. 0 St. None 2-4 Next day 8. Cancellation Ret. ? St. None 3-5 No data 9. S-W illusion 0 0 0 General 10. Steadiness ? Unsteadiness None 1-3 3-4 11. Sleep quality Individual differences 12. Sleep quantity depending on body weight 2 ? 13. General health and conditions of administration

Subsequent to these investigations was that of Hollingworth[312] which is at once the most comprehensive, carefully conducted, and scientifically accurate one yet performed. He employed an ample number of subjects in his experimentation; and both his subjects, and the assistants who recorded the observations, were in no wise cognizant of the character or quantity of the dose of caffein administered, the other experimental conditions being similarly rigorous and extensive.

The purpose of his study was to determine both qualitatively and quantitatively the effect of caffein on a wide range of mental and motor processes, by studying the performance of a considerable number of individuals for a long period of time, under controlled conditions; to study the way in which this influence is modified by such factors as the age, sex, weight, idiosyncrasy, and previous caffein habits of the subjects, and the degree to which it depends on the amount of the dose and the time and conditions of its administration; and to investigate the influence of caffein on the general health, quality and amount of sleep, and food habits of the individual tested.

To obtain this information the chief tests employed were the steadiness, tapping, coordination, typewriting, color-naming, calculations, opposites, cancellation, and discrimination tests, the familiar size-weight illusion, quality and amount of sleep, and general health and feeling of well-being. A brief review of the results of these tests is given in the tabular summary.

From these Hollingworth concluded that caffein influenced all the tests in a given group in much the same way. The effect on motor processes comes quickly and is transient, while the effect on higher mental processes comes more slowly and is more persistent. Whether this result is due to quicker reaction on the part of motor-nerve centers, or whether it is due to a direct peripheral effect on the muscle tissue is uncertain, but the indications are that caffein has a direct action on the muscle tissue, and that this effect is fairly rapid in appearance. The two principal factors which seem to modify the degree of caffein influence are body weight and presence of food in the stomach at the time of ingestion of the caffein. In practically all of the tests the magnitude of the caffein influence varied inversely with the body weight, and was most marked when taken on an empty stomach or without food substance. This variance in action was also true for both the quality and amount of sleep, and seemed to be accentuated when taken on successive days; but it did not appear to depend on the age, sex, or previous caffein habits of the individual. Those who had given up the use of caffein-containing beverages during the experiment did not report any craving for the drinks as such, but several expressed a feeling of annoyance at not having some sort of a warm drink for breakfast.

It is interesting to note that he also found a complete absence of any trace of secondary depression or of any sort of secondary reaction consequent upon the stimulation which was so strikingly present in many of the tests. The production of an increased capacity for work was clearly demonstrated, the same being a genuine drug effect, and not merely the effect of excitement, interest, sensory stimulation, expectation, or suggestion. However, this study does not show whether this increased capacity comes from a new supply of energy introduced or rendered available by the drug action, or whether energy already available comes to be employed more effectively, or whether fatigue sensations are weakened and the individual's standard of performance thereby raised. But they do show that from a standpoint of mental and productive physical efficiency "the widespread consumption of caffeinic beverages, even under circumstances in which and by individuals for whom the use of other drugs is stringently prohibited or decried, is justified."

Conclusion

Brief summarization of the information available on the pharmacology of coffee indicates that it should be used in moderation, particularly by children, the permissible quantity varying with the individual and ascertainable only through personal observation. Used in moderation, it will prove a valuable stimulant increasing personal efficiency in mental and physical labor. Its action in the alimentary regime is that of an adjuvant food, aiding digestion, favoring increased flow of the digestive juices, promoting intestinal peristalsis, and not tanning any portion of the digestive organs. It reacts on the kidneys as a diuretic, and increases the excretion of uric acid, which, however, is not to be taken as evidence that it is harmful in gout. Coffee has been indicated as a specific for various diseases, its functions therein being the raising and sustaining of low vitalities. Its effect upon longevity is virtually nil. A small proportion of humans who are very nervous may find coffee undesirable; but sensible consumption of coffee by the average, normal, non-neurasthenic person will not prove harmful but beneficial.