The chemistry of cooking and cleaning; a manual for house keepers

Preface

IN this age of applied science, every opportunity of benefiting the household should be seized upon.

The family is the heart of the country's life, and every philanthropist or social scientist must begin at that point. Whatever, then, will enlighten the mind, and lighten the burden of care, of every housekeeper will be a boon.

At the present time, when the electric light and the gas stove are familiar topics, there is, after all, no branch of science which might be of more benefit to the community, if it were properly understood, than Chemistry — the Chemistry of Common Life.

There is a space yet unoccupied for an elementary work which shall give to non-scientific readers some practical information as to the chemical composition of articles of daily use, and as to their action in the various operations in which they are employed.

The public are the more ready for the application of this knowledge since Chemistry is taught in nearly all High Schools, and most persons have a dim idea of what some part of it means. To gather up these indistinct notions into a definite and practical form is the aim of this little book.

iv PREFACE.

There is, lingering in the air, a great awe of chemistry and chemical terms, an inheritance from the age of alchemy. Every chemist can recall instances by the score in which manufacturers have asked for recipes for making some substitute for a well-known article, and have expected the most absurd results to follow the simple mixing of two substances. Chemicals are supposed by the multitude to be all-powerful, and great advantage is taken of this credulity by unscrupulous manufacturers.

The number of patent compounds thrown upon the market under fanciful and taking names is a witness to the apathy of housekeepers. It is time that they should bestir themselves for their own protection. A little knowledge of the right kind cannot hurt them, and it will surely bring a large return in comfort and economy.

These mysterious chemicals are not so many or so complicated in structure but that a little patient study will enable any one to understand the laws of their action, so far as they apply to the common operations of the household.

No attempt is here made to cover the whole ground of chemical science, but only to explain such of its principles as are involved in the raising of bread, and in a few other common processes.

PREFACE

To the Second Edition.

THE science of chemistry has made rapid strides in the past fifteen years. Biological science has sprung from infancy to sturdy manhood during the same time, and a knowledge of both with their relations to each other is necessary to the right understanding of the manifold operations of life. All the sciences and all the arts are taxed by thej intelligent home-maker for the proper foundation and continuance of the complex life of the home.

The establishment of more homes and their right conduct when established, which results in the better utilization of time, money and strength, means the perpetuity, prosperity and power of the nation.

Without trespassing upon the domain of household bacteriology, a knowledge of the chemistry of cooking and cleaning must include some discussion of the sources of dirt, its composition and its dangers, and the discussion of methods for its removal, which shall at the same time be speedy, safe and effectual.

vi PREFACE.

Experience teaches that in domestic work there is no best rule of universal application. Circumstances vary so widely that principles, alone, can be laid down. Each case requires a large proportion of judgment — a compound of more complex composition than any chemical substance ever dealt with.

If any housekeeper finds a method better for her purpose than the one specified here, let her keep to its use and tell it to others. This work will have accomplished its purpose if it interests those who understand already the principles of cooking and cleaning; gives a few answers to those who continually ask "Why?" and "How?" and stimulates to study and thought the many who have long labored with willing hearts but with untrained minds and hands.

Boston, 1897.

PART I. Introduction I

I. Matter and Its Composition ... 5

II. Elementary Chemistry 12

III. Starches, Sugars, Fats, Their Preparation

as Food . .24

IV. Nitrogenous Constituents .... 47

V. Flavors and Condiments. Diet ... 56

• PART II.

I. Dust . 71

II. Dust Mixtures (Grease and Dust) . . 87

III. Stains, Spots, Tarnish 100

IV. Laundry 118

V. Chemicals, and Their Use in the House-

hold 145

VI. Antiseptics, Disinfectants, Insecticidfs . 165

Books of Reference 181

Introduction

To the Revised Edition of 1907.

IN the thirty years since this little book was written, the interpretation of many scientific facts has been changed as more facts have been discovered, and also, in many cases, the method of expressing the well-established facts has been changed to agree with newer theories.

Although at first sight this seems discouraging, it should not prevent an attempt to understand some of the fundamental laws upon which every-day life and health depend. The author has already learned three different systems of expressing the same facts in chemistry and expects to learn yet another.

In making this revision a medium course has been chosen. It is not prepared for the scientific man, but its mission is now, as it has been heretofore, to the average intelligent housewife. She needs to see that there are reasons for things in order to lift the monotonous operations of the kitchen in particular, and the household in general, from distasteful drudgery to a plane of intelligent direction of scientific processes, the results of which may be more or less controlled.

It is this sense of control, of power to produce desired results, which gives an interest to daily duties. Since the good health and earning capacity of the family depend upon the housemother's knowledge of the laws which govern the daily making and baking and cleaning, surely it will be worth her while to try to absorb the spirit of modern scientific research, to observe what goes on in her pots and pans, to watch her oven, and especially to scrutinize her dish washing.

Knowledge of foods and of chemical processes is increasing so rapidly that what is written is out of date before the ink is dry, but a little more or less exact information is not so important as that the spirit of inquiry, of openmindedness, shall pervade all departments of household activity.

Thirty years ago very few grown women had received any training in chemistry. Chemical nomenclature was worse than Greek to them. Today the majority of young housewives have a small remnant of school chemistry among their store of miscellaneous knowledge. It is to be feared that it is rather vague, but chemistry is not the bugbear it once was. The present day housewife is not afraid of chemical substances.

The great difficulty in explaining chemical results has been in showing the law of definite proportions, that fundamental law, discovered by Dalton, in and upon which the whole theory has been built.

The law of exchange of different quantities having different values not according to quantity, but according to value, has always been difficult to express.

One reason for dwelling upon the law of definite proportions is because the idea is so prevalent that if the effect of a teaspoonful is good, that of a teaspoonful and a half is better, whereas the extra half may be the cause of failure. The long experience of a grocery clerk gives his hand nerves such a response to weight that he may dispense with scales in putting up a pound of sugar. In this way the skilled cook tells the proportions with the exactness of the balance, but woe betide the unskilled housewife who attempts the same trick.

One other fact in relation to science, and chemical science in particular, must be borne in mind. While much is known, there remains much more still hidden. It is practical wisdom to use all that is known and to accept results as far as they prove beneficial, without waiting to learn all the reasons why. Not that the search for reasons should be abandoned, but that each bit of knowledge should be applied as fast as gained.

THE CHEMISTRY OF COOKING AND CLEANING.

CHAPTER I. Matter and Its Composition

WE give the name matter to the objects Matter which can be recognized by any one of our senses. There are many kinds of matter and many forms of one kind. Ice melts into water, water changes into steam. In our stoves, the hard, black coal disappears, leaving a soft, gray ash, that weighs much less than the original coal. Something has been taken away.

The leaf is covered by wind-blown soil and Chang soon no leaf is there ; but the matter of which it was composed is still somewhere, for that is never lost. Living matter is in constant change from one form to another. Our bodies are composed of matter, and to their continued existence, as well as to their growth, material substances are necessary. Some changes come quickly, some slowly. Years, ages even, are sometimes necessary to bring about a result that is visible to us.

es in Matter.

A familiar substance, sugar, for example, may be subjected to different changes. Put two tablespoonfuls of white sugar into a scant half cup of water. The sugar disappears. The clear water changes to a syrupy liquid. If the water is allowed to evaporate slowly, the sugar is found to remain.

A teaspoonful of sugar dropped upon the warm stove changes in character. There appears a black mass, which is readily recognized as charcoal.

Add a solution of an acid to a solution of an alkali, and observe that the acid substance and the alkaline substance are no longer in existence as such. There is, instead, a neutral saline substance dissolved in water. The new substance has the properties of neither of the others. The acid and the alkali have lost their identity.

Dissolve a teaspoonful of sugar in a cupful of water. Add a very little yeast and put the cup in a warm place. Soon bubbles of gas rise and break on the surface; while, on distilling the liquid, a new acquaintance presents itself in the form of alcohol. The first-mentioned change in the sugar — the solution of it in water — is a physical change; for the character of the substance is not permanently altered. The second change — the charring — is a chemical change — the substance loses its individual character. The third change in the sugar — its fermentation — which is most important for our present purpose, is also a chemical change but one caused by the action of life. When the syrup ferments, we know that living organisms are at work in the solution, changing the substance by their own processes of growth. To this class, then, we may apply the name biological change. Here belong the changes in our own bodies which enable them to live and grow. Death comes when these " vital" changes can no longer proceed in a normal, healthy manner.

Changes in matter, then, are of two kinds.

I. Physical. Change of form, without permanent loss of identity. This is brought about by outside forces : heat, blows, etc.

II. Chemical. Complete change of character, with or without change of form. This is brought about by chemical agencies, by fire and electricity — also forces from without.

Physical and chemical forces, working together, allow biological results, caused by living cells producing energy by means of their life processes.

Under these heads come the numerous changes which every housewife observes and which all should understand, so far as such understanding is necessary for the true economy of the house.

Forms of Matter.

We have seen that matter is subject to two kinds of change. Experience teaches that matter exists in three different forms — solids, liquids and gases. It teaches, also, that by the action of outside forces some solids become liquids and some liquids become gases. The reverse process, also, is known — gases change into liquids and liquids into solids. The chemist or physicist is able to change matter from one form into another in many more- instances than are observed in ordinary experience.

What causes can be made to bring about these changes ? Before an iron kettle or stove can be made, the metal from which it is formed must be subjected to intense heat, when it will become a liquid and can be poured into molds of any desired shape. Solid ice melts or becomes water at a low temperature; but at a higher degree of temperature, the water becomes steam or gas. Some solids, as camphor and iodine, sublime, that is, pass directly into the gaseous form.

Heat, then, is one influence which brings about a change of state in material substances. If heat be abstracted from a liquid, the latter may become a solid, as when water becomes ice. Like changes are less readily brought about by pressure, gases becoming liquids ; liquids becoming solids. Cold and pressure, acting together, are able to liquefy the air, and other gases once called permanent.

Different degrees of heat produce varying Expansion, degrees of liquefaction. Sometimes only a semi-liquid state results, as in the melting of solder, of gelatine and of tar. Almost all matter (except water between 32 ° and 39 ° Fahrenheit) expands or occupies more space under the action of heat ; but in gases the proportion of expansion is much the greatest. This expansion of gases with heat makes possible the process of ventilation by means of an open fire, and is one factor in the rise of dough.

The solids may also be changed to liquids. Solution. The degree of solubility of any substance depends largely upon the temperature of the solvent. Common salt dissolves nearly as well in cold as in warm water. "Soda" and alum dissolve more readily in warm than in cold, while cream of tartar requires hot water for its complete solution.

The amount of solid which water will dissolve Saturation, usually increases with the temperature to a certain degree. After this no more will dissolve and the solution is " saturated." Gases readily dissolve in water, but usually in cold solutions only.

The action of the liquid is more rapid if the

Solvents.

Swelling.

solid be first powdered, for a greater area is thus presented to the action of the liquid. It is also usually more rapid when the substance is placed upon or near the surface. Under these conditions each particle, while dissolving, is surrounded by a thin envelop of syrup, which becomes heavier and sweeter. The film of syrup sinks into the solvent liquid, so that a clean surface is continually exposed to be acted upon. Solution is a valuable agent in bringing about chemical action during many processes of cooking and cleaning.

Water is a nearly universal solvent. It dissolves larger quantities of more substances than any other liquid. Some solids, however, dissolve more readily in other liquids, as camphor in alcohol. Silver, copper and tin are not perceptibly dissolved in pure water, while most of their compounds, as nitrate of silver and sulphate of copper, are thus soluble. Lead dissolves more readily in pure water than in that containing some impurities. Gold may be dissolved in a warm mixture of two strong acids. Many of these metallic solutions which may be formed in cooking utensils and water pipes are poiscnous, and a knowledge of them becomes a matter of great importance to all housekeepers.

A process of daily occurrence in the household greatly resembles solution. It consists in the taking up of water, which produces an increase of bulk or " swelling," but no true solution. Gelatine swells in cold water and may then be dissolved in hot water. Starch "jells" by taking up water; so we soak the cereals which consist largely of starch, that they may be more quickly acted upon by heat.

M

CHAPTER II. Elementary Chemistry

OST substances with which we deal in ordinary life are compounds of two or more elementary constituents. The grain of wheat, the flesh of animals, the dangerous poison, are each capable of separation into simpler substances. Finally a substance is found which cannot be further separated. A chemical clement is a substance which cannot be decomposed into other substances.

Elements. Pure gold is an element from which nothing

can be taken different from itself, but gold coin contains a little copper or silver or both. The oxygen of the air is an element. Air is a mixture of two or more elements. Oxygen and hydrogen, both gaseous elements, unite in certain proportions to form the chemical compound, water.

There are about eighty of these elements known to the chemist, while their compounds are infinite. For his convenience the chemist abbreviates the names of the elements into syn> bols, which he uses instead of the names. Usually, the first or the first two letters of the Latin name are taken. These symbols mean much more, however, than time saved, as we shall see.

Most of the elements unite with each other. Compounds. Then in the resulting compounds, one or more elements may be exchanged for others, so that a multitude of combinations are formed out of few elementary substances. The bulk of our food, clothing and furniture is made up of only five or six of these elements, although about twenty of them enter into the compounds used in the household. The others are found in nature, in the chemical laboratory or in the physician's medicine case. A few are so rare as to be considered curiosities.

Every housewife should understand something chemical Laws, of these chemical substances — their common forms, their nature and their reactions, that she may not be cheated out of time and money, and, more important still, that she may preserve the health of those for whom she cares.

All chemical changes are governed by lazvs. Under like conditions, like results follow. No chemical sleight of hand can make one pound of washing soda do the work of two pounds, or one pound of flour make a third more bread at one time than at another,

Pr<T P oJti<5 l e s finite One °^ tne most important of these laws is that known as the Laiv of Definite Proportions, which states that the various elements do not unite to form chemical compounds in any proportions whatever, but only in perfectly definite proportions. From this it follows that to the elements can be assigned values which represent the quantities of them which enter into combination with each other. These values are called the combining weights or atomic weights of the elements, the latter term having been introduced since it is assumed that the elements are built up of extremely small particles of matter called atoms, and that compounds are made of groups of these atoms called molecules, and since under this assumption the relative weights of the elements which unite represent the relative weights of the atoms or multiples of them. Thus, in the compound water, hydrogen and oxygen are present always in perfectly definite proportions, namely, in the relation of one part by weight of hydrogen to eight parts by weight of oxygen ; and in the compound acetylene, the elements carbon and hydrogen are always present in the proportion of one part of hydrogen to twelve parts of carbon. It is customary to adopt as the standard of reference one part by weight of hydrogen and to adopt as the combining weight or atomic weight of other elements that quantity of them which combines with one part of hydrogen, or in some cases with two or more parts of this element.

Upon this basis the atomic weight of oxygen is sixteen and that of carbon twelve times the atomic weight of hydrogen. The symbol of an element is made to represent its constant atomic weight ; so that, while the word oxygen means only the collection of properties to which is given the name, the symbol O indicates a definite quantity of oxygen which is sixteen times the weight of hydrogen represented by the symbol H.

While it is always true that the elements com- Law of Multiple bine with each other only in definite proportions, yet it is often true that they combine to form two or more definite compounds. Such combinations are governed by the Law of Multiple Proportions: When elements form more than one compound, they unite according to some multiple of their combining weights.

Thus, sulphur and oxygen form two difTerent compounds represented by- the symbols S0 2 and S0 3 — where the proportions of sulphur to oxygen are thirty-two to thirty-two for the first and thirty-two to forty-eight for the second, the combining weight corresponding to the symbol S being thirty-two.

Proportions.

A partial list of atomic weights is as follows:

Element.

Symbol.

At. weight.

Element. Symbol.

At. weight.

Aluminum

Al

Magnesium

Mg

24.36

Calcium

Ca

Nitrogen

N

14.04

Carbon

C

Oxygen

O

Chlorine

CI

35-45

Phosphate

P

Copper

Cu

63.6

Potassium

K

39-15

Gold

Au

197.2

Radium

Ra

Hydrogen

H

1.008

Silicon

Si

28.4

Iodine

I

126.97

Silver

Ag

Iron

Fe

55-9

Sodium

Na

23-05

Lead

Pb

206.9

Sulphur

S

32.06

Lithium

Li

7-03

Zinc

Zn

Symbols. Tri e symbols, then, are the chemist's shorthand

alphabet, or his sign language. The non-scientific reader is apt to look upon the acquisition of this sign language as the schoolboy regards the study of Chinese — as the work of a lifetime. He would be near the truth were he to attempt to remember the symbols of all the complicated compounds known and constantly increasing; but a study of the properties and combinations of the few which make the common substances of daily use need not frighten the most busy housewife, for they can be comprehended in a few hours of thoughtful reading. Then a little practice will make them as familiar as the recipe of her favorite cake. "To master the symbolical language of chemistry, so as to fully understand what it expresses, is a great step toward mastering the science."

The exchanges and interchanges among the Reactions, elements by which new compounds are produced are called chemical reactions. The written expression of the reaction is called a chemical equation. In all chemical equations there is just as much weight represented on one side of the sign of equality ( = ) as on the other.

12 + 32 = 44 Carbon. Oxygen. Carbon Dioxide.

HC1 + NaOH = NaCl + H 2

Hydro- Sodium Sodium Water,

chloric Hydrate. Chloride,

Acid. or Com-

mon Salt.

This shows that the sum of the weights of the two substances taken is equal to the sum of the weights of the new substances formed as the result of the reaction.

It is this exactness in dealing with matter which gives to the study of chemistry its great value from an educational standpoint. In the economy of nature nothing is lost. Wood and coal burn in our stoves. The invisible product of their combustion, C0 2 , passes into the air, but adds a definite amount to the weight of the air. Thus the symbol of this product shows that twelve pounds of coal (which when free of ash is nearly pure carbon) in burning take from the air thirty-two pounds of oxygen and give back to the air forty-four pounds of carbon dioxide.

Similarly the symbol of water, H 2 (atomic weights, H = I, O = 16), shows that for every eighteen parts by weight of water produced, there will be two parts by weight of H and sixteen parts by weight of O required.

Although the phenomena themselves are found to be unchangeable, our explanation of them may be modified as our knowledge increases.

Present theories penetrate only a little into the real essence of things, and the investigator soon stumbles upon questions whose explanation does not at present even seem to be a possibility.

(See late text-books on chemistry for the difference between ions and atoms.) Oxidation. One of the most important chemical changes

that takes place inside or outside the animal body is that union of oxygen (four-fifths of the air) with carbon or hydrogen which we call oxidation — under. the steam boiler and in the stove it is called combustion. It is the chief source of available power or energy in either case. (See pp. 25, 26.)

The same amount of heat is evolved when a given amount of. substance is oxidized, whether the combustion takes place slowly or rapidly.

An appreciation of these fundamental laws of The

i-i 1 • • 11 »• 1 Calorimeter.

chemical combination is needed to realize the significance of the recent work on the use of food in the human body as demonstrated in the calorimeter.

Before a study of the chemical composition of food materials and of the chemical and physical changes occurring in the processes of cooking as a preparation for the best utilization of these food stuffs could be insisted upon, it was necessary to be convinced that the utilization of the chemical compounds, such as sugar, starch, albumin, etc., was the same in effect within the body as without, in stove or furnace.

For the proof that the law of the conservation of energy held in the life processes going on in the human body, an examination of the food and of the results of its consumption was imperative.

For this purpose a " respiration calorimeter" was set-up.*

"This is a metal-walled chamber in which- a man lives, eats, drinks, works and sleeps. Provision is made for ventilating the chamber and for regulating the temperature and moisture of the air within it. The volume of the ventilating air current is measured and samples for analysis are taken before and after it passes through the chamber, thus obtaining the amounts of carbon dioxide and water in the respiratory products. The food, drink, feces and urine are weighed and analyzed, and their potential energy is determined, as is the kinetic energy given off from the body in the forms of heat and external muscular work.

"The devices for measuring the heat or loss of heat given off from the body include : ( I ) Arrangements to prevent gain or loss of heat in the chamber either by the passage of heat through the walls or the bringing in and taking out of heat in the ventilating air current; (2) arrangements by which the heat given off in the chamber, by the body or otherwise, is carried out by a current of water. . . . This current, which is conveyed by copper pipes, comes into the chamber at a low temperature, passes around the interior, absorbs the heat, and goes out correspondingly warmer. The quantity of the water and the rise of temperature show how much heat is carried out."

*" Description of a New Respiration Calorimeter and Experiments on the Conservation of Energy in the Human Body," by W. O. Atwater, Ph.D; ; Professor of Chemistry, Wesleyan University, and E. B. Rose, Ph.D., Professor of Physics, Wesleyan University.

By means of such apparatus there may be de- J/^jg 11 Value termined questions pertaining to the demands Ex P erim ents. of the body for nutriment under different conditions of work and rest ; the duties performed by the different nutrients of food in supplying the needs of the body; and finally the nutritive values of food materials and the amount and proportions best adapted to the needs of people of different classes, with different occupations and in different conditions of life.

By experiment it has been found that I gram of carbohydrates (starch, sugar, etc.) or proteids (lean meat, white of egg, etc.) gives on an average about 4.1 calories,* and one gram of fats 9.3 calories. Therefore to find the value of a given dish set upon the family table is simple when the weights of the ingredients are known. For instance, in a curry stew with rice, three pounds of medium fat beef will yield 259 grams proteid and 175 grams of fat, while ten ounces of rice will yield 22.5 grams proteid, 1 gram of fat and 222 grams of carbohydrates. Adding together the carbohydrate and proteid gives 503.5 grams. Multiplying this number by the 4.1 calories per gram we have 2,064 calories; while multiplying the 176 grams of fat by 9.3 gives 1,636 calories for the fat, a total of 3,700 calories, or as many

* For definition of calories, see page 47.

as should be supplied by a dinner for three working men.

The housewife well understands that she may provide sufficient food, but that she cannot be sure it will be eaten, or assimilated if it is eaten. But she must also understand that power does not come from nothing, and that if sufficient nourishment is not provided, the body cannot have its full due. iwifrs One °^ ^ le un i versa l chemical operations in

the household is the use of cream of tartar and baking soda or of baking powders. Advantage has been taken of this fact to put upon the market many substitutes and variations with the natural result that the housewife is confused and uncertain. The table on page 23 may be helpful in clearing up some of the mysterious ways of the substances themselves and of their advocates.

Thus, 84 parts of cooking soda unite with 188 parts of cream of tartar — if both are pure — to give 44 parts of the gas C0 2 . Cream of tartar is a compact powder, however, so that a teaspoonful will weigh more than a teaspoonful of soda, and illustrates the difference in accuracy between weighing and measuring. Because cream of tartar is so liable to cake, a starch is added to the mixing for baking powder. For home preparation 5 to 10 per cent will be enough.