General medicine chemistry for the use of practitioners of medicine

Front matter

UNITED STATES OF AMERICA.

August.

GENERAL

Preface

Ik the arrangement of this work, it has been deemed advisable to depart, in certain points, from the methods usually followed in chemical text-books. Those portions treating of technical processes have been condensed to a minimum, while the bearings of chemistry upon physiology, hygiene, therapeutics, and toxicology, have been treated of as fully as the limits of the work have permitted. The division of the elements into metals and metalloids has been abandoned as unscientific, and a classification has been adopted which the author believes to possess advantages over those hitherto followed, especially in that it is based upon purely chemical characters.

Organic chemistry has not been considered as a distinct division of the subject, but simply as the chemistry of the compounds of carbon; an arrangement not only logical, but sanctioned by the works of Feser, Schutzenberger, and others. The classification of the carbon compounds is based, as far as possible, upon their relations to the different series of hydrocarbons.

The size of the volume being limited, the author has preferred to abstain from the use of illustrations, thinking that the space could be better utilized as it has been. Through mistake of the printer in casting up the copy, he has also been obliged to condense that portion of the work treating of the third and fourth classes of elements more than he wished, and quite out of proportion to the rest of the work.

It is hardly necessary to state that the modern system of notation has been followed. All weights and measures are given in the metric system, and temperatures in degrees of the Centigrade scale.

E. A. W.

Introduction

PAGE

General properties of matter 2

Elements and compounds 7

Laws governing the combination of elements 7

The atomic theory 8

Atomic and molecular weights 11

Symbols, formulae, equations , 16

Radicals, acids, bases, salts 17

Nomenclature 20

Oxides, hydrates, and chlorides 23

Typical f ormulas and formulae of constitution 23

Classification of elements 26

Physical characters of chemical interest 28

SPECIAL CHEMISTRY.

Elements of Class 1 33

Elements of Class II 09

Chlorine Group 69

Fluorine 69

Bromine 77

VI CONTENTS.

PAGK

Sulphur Group 82

Selenium and tellurium 93

Nitrogen Group <, 94

Air i 95

Arsenic f , 116

Antimony 131

Boron Group 139

Carbon Group. 141

Classification of carbon compounds 148

First series of hydrocarbons 157

Second series of hydrocarbons 227

Third series of hydrocarbons 287

Fourth series of hydrocarbons 292

Fifth series of hydrocarbons 315

Sixth series of hydrocarbons 334

Seventh series of hydrocarbons 336

Eighth series of hydrocarbons 336

Ninth series of hydrocarbons 337

Tenth series of hydrocarbons 337

Eleventh series of hydrocarbons 337

Higher series of hydrocarbons 338

Cyanogen compounds 342

Glucosides 342

Alkaloids 346

Animal ferments 368

Animal coloring matters 369

Silicon 372

Molybdenum Group 373

Elements of Claso III 374

Gold Group 374

Iron Group 374

Chromium 375

Manganese 376

Iron 377

Aluminium Group 381

CONTENTS. Vll

PAGE

Lead Group 384

Lead 384

Bismuth Group 388

Bismuth 388

Tin Group 390

Tin 390

Platinum and Rhodium Groups— 392

Elements of Class IV 393

Sodium Group 393

Silver 407

Ammonium 408

Calcium Group 411

Magnesium Group 416

Zinc 418

Nickel Group 419

Nickel 419

Cobalt 419

Copper Group 420

GENERAL

MEDICAL CHEMISTRY.

Part 1. INTRODUCTION

It is difficult to give at the outset a clear and concise idea of what is understood as chemical science. The best and simplest definition of chemistry is a modification of that given by Webster: That branch of science which treats of the composition of substances, their changes in composition, and the laws governing such changes. It will be seen that the essential character of the science is that it has to deal with comjiosition, and in this the line between physical and chemical phenomena is more sharply drawn than that between the individual varieties of the former.

A bar of soft iron is the same in composition, whether it be hot or cold, luminous or non-luminous, magnetized or not magnetized. When, however, it comes under the dominion of chemical action, its composition is changed, and, although the resulting substance contains iron, it differs in its appearance and properties from that metal. Moreover, this change in composition, once brought about, is permanent until another change is Avrought by another manifestation of chemical action; on the other hand, the peculiar property communicated to a substance by a physical force is temporary, and only manifested during the action of that force.

However distinct chemical may thus be from physical forces, it is none the less united with them in that grand correlation whose existence was first announced by Grove, in 1842. As, from chemical action, manifestations of every variety of physical force may be obtained: light, heat and mechanical force from the oxidation of carbon; and electrical force from the action of zinc upon sulphuric acid — so does chemical action have its origin, in many instances, in the physical forces. Luminous rays bring about the chemical decomposition of the salts of silver, and the chemical union of chlorine and hydrogen; by electrical action a decomposition of many compounds into their constituents is instituted, while instances are abundant of reactions, combinations, and decompositions which require a certain elevation of temperature for their production. While, therefor, chemistry in the strictest sense of the term deals only with those actions which are attended by a change of composition in the material acted upon, yet chemical actions are so frequently, nay universally, affected by existing physical conditions, that the chemist is obliged to give his attention to the science of physics, in so far, at least, as it has a bearing upon chemical reactions, to chemical physics — a branch of the subject which has afforded very important evidence in the support of theoretical views originating from purely chemical reactions.

General Properties of Matter.

Indestructibility. — The result of chemical action is change in the composition of the substance acted upon, a change accompanied by corresponding alterations in its properties. Although we may cause matter to assume a variety of different forms and render it, for the time being, invisible, yet in none of these changes is there the smallest particle of matter destroyed. When carbon is burned in an atmosphere of oxygen, it disappears, and, so far as we can learn by the senses of sight or touch, is lost; but the result of the burning is an invisible gas, whose weight is equal to that of the carbon which has disappeared, plus the weight of the oxygen required to burn it.

Weight. — All bodies attract each other with a force which is in direct proportion to the amount of matter which they contain. The force of this attraction exerted upon surrounding bodies by the earth becomes sensible as weight, when the motion of the attracted body toward the centre of gravity of the earth is prevented.

In chemical operations we have to deal with three kinds of weight : apparent, absolute, and specific.

The apparent weight, or relative weight, of a body is that which we usually determine with our balances, and is, if the volume of the body weighed be greater than that of the counterpoising weights, less than its true weight. Every substance placed in a liquid or gaseous medium suffers a loss of apparent weight equal to that of the volume of the medium so displaced, and is buoyed up to that extent. A cork placed in water sinks until it has displaced a volume of water whose weight is equal to its own. For this reason the apparent weight of some substances may be a minus quantity; thus, if the air contained in a vessel suspended from one arm of a poised balance be replaced by hydrogen, that arm of the balance to which the vessel is attached will rise, indicating a diminution in weight.

The absolute weight of a body is its weight in vacuo. It is only determined in very accurate chemical work, by placing the entire weighing apparatus under the receiver of an air-pump, or, in the case of gases, approximately, by first weighing the vessel from which the air has been pumped, and afterward filled with the gas.

By the specific weight, or specific gravity of a substance, is understood the weight of a given volume of that substance as compared with the weight of an equal volume of some substance taken as a standard of comparison. It is a well-known fact that equal volumes of different substances differ from each other in weight; thus, a litre of hydrogen weighs

GENERAL PROPERTIES OF MATTER. 3

0.0896 grams, while the same volume of platinum weighs 21.500 grams, or about 200,000 times as much.

The substance taken as the unit of the specific gravities of solids and liquids is water. The specific weights of gases are usually referred to air as a unit; it is better, however, to adopt hydrogen as such unit (see p. 15). When we say that the specific gravity of sulphuric acid is 1.8, we mean that, volume for volume, sulphuric acid is one and eight-tenths times as heavy as water.

The determination of the specific weight of a substance is frequently of great service. Sometimes it affords a rapid means of distinguishing between two substances similar in appearance; sometimes in determining the quantity of an ingredient in a mixture of two liquids, as alcohol and water; and frequently in determining approximately the quantity of solid matter in solution in a liquid; it is the last object which we have in view in determining the specific gravity of the urine.

An aqueous solution of a solid has a higher specific gravity than pure water, the increase in specific gravity following a regular but different rate of increase with each solid. In a simple solution — one of common salt in water, for instance — the proportion of solid in solution can be determined from the specific gravity. In complex solutions, such as the urine, the specific gravity does not indicate the proportion of solid in solution with accuracy. In the absence of sugar and albumen, a determination of the specific gravity of urine affords an indication of the amount of solids sufficiently accurate for usual clinical purposes. Moreover, as urea is much in excess over other urinary solids, the oscillations in the specific gravity of the urine, if the quantity passed in twenty-four hours be considered, and in the absence of albumen and sugar, indicate the variations in the elimination of urea, and consequently the activity of disassimilation of nitrogenous material.

To determine the specific gravity of substances, different methods arc adopted, according as the substance is in the solid, liquid, or gaseous state ; is in mass or in powder; or is soluble or insoluble in water.

Solids. — First. The substance is heavier than water, insoluble in that liquid, and not in powder. It is attached by a fine silk fibre to a hook suitably situated on one arm of the balance, and weighed. A beaker full of pure water is so arranged that the substance, still attached to the balance, is immersed in the liquid; in which condition it is again weighed. The second weight will be found to be less than the first. By dividing the weight in air by the loss in water the specific gravity, water=1.00, is obtained. Example:

A piece of lead weighs in air 82.0

A piece of lead weighs in water 74.9

Loss in water 7.1

82.0

11.55 = sp. gr. of lead.

7.1

If the substance be in fine powder, the specific gravity bottle (see p. 4) is used. The bottle, filled with water, and the powder, previously weighed and in a separate vessel, are weighed together. The water is poured out of the bottle, into which the powder is then introduced, with enough water to fill the bottle completely. The weight of the bottle and its contents is now determined, and is less than the first weight by the weight of the volume of water displaced by the powder. Here again the specific gravity is obtained by dividing the weight of the powder alone by the loss between the first and second weighings.

Second. — If the substance be lighter than water, a sufficient bulk of some heavy substance, whose specific gravity is known, is attached to it and the same method followed, the loss of weight of the heavy substance being subtracted from the total loss. Example:. >'

A fragment of wood weighs 24

A fragment of lead weighs 44

Wood with lead attached weighs 68

Wood with lead attached weighs in water. ... 16

Loss of weight of combination 52

Loss of weight of lead in water 6

Loss of weight of wood 46

Third. — If the substance be soluble in water, its specific gravity, re- • f erred to some liquid in which it is insoluble and whose specific gravity is known, is determined by using that liquid as water is used in 1°. From this the specific gravity of the solid, referred to water, is determined by multiplying the specific gravity so obtained by that of the liquid used. Example:

A piece of potassium weighs 2.576

A specific gravity bottle full of naphtha, sp. gr. 0.758,

weighs 22.784

25.360 The bottle with potassium and naphtha weighs 23.103

2.576

2.257

Liquids. — The specific gravity of liquids is determined by the specific gravity bottle, sometimes called picnometer, or by the spindle or hydrometer.

First. — The method by the bottle is the more accurate, and, if a balance be at hand, easily conducted. A bottle of thin glass is so made as to contain exactly a given volume of distilled water at a given temperature, say 100 c.c. at 15° C. ; the weight of the bottle is also known once for all. To use the picnometer, it is'simply filled with the liquid to be ex-

GENERAL PROPERTIES OF MATTER. 5

amined and weighed. The weight obtained, minus that of the bottle, is the specific gravity sought if the bottle contain 1000 c.c; y 1 ^ if 100 c.c, etc. Example: having a bottle whose weight is 35.35, and which contains 100 c.c; filled with urine it weighs 137.91, the specific gravity of the urine is 137.91-35.35 = 102.56x10=1025.6 "Water =1000.

Second. — The method by the hydrometer is based upon the fact that a solid will sink in a liquid until it has displaced a volume of the liquid whose weight is equal to its own; and all forms of hydrometers are simply contrivances to measure the volume of liquid which they displace when immersed. The appearance of the hydrometer most used by physicians, the urinometer, is too well known to require description. It should not be chosen too small, as the larger the bulb and the thinner and longer the stem, the more accurate will be its indications. Owing to prevailing carelessness in the manufacture of urinometers and to the impossibility of reading the graduations with the same accuracy that can be attained in detecting small differences in weight, their indications are never as precise as those obtained by the picnometer.

In all determinations of specific gravity it is of great importance to have the liquid examined at the temperature for which the instrument is graduated, for the reason that all liquids expand with heat and contract when cooled, and consequently the result obtained will be too low if the urine or other liquid be at a temperature above that at which the instrument is intended to be used, and too high if below that temperature. An accurate correction may be made for temperature in simple solutions; in a complex fluid like the urine, however, this can only be done roughly by allowing 1° of specific gravity for each 3° C. (5.4° Fahr.) of variation in temperature.

The determination of the specific gravity of gases and vapors requires all the facilities of a well-appointed laboratory, and, although of the greatest importance to the chemist (see p. 15), will rarely be attempted by the physician.

States of Matter. — Matter exists in one of three states, solid, liquid, and gaseous. In the solid form the particles of matter are comparatively close together, and are separated with more difficulty than are those of liquid or gaseous matter; or, in other words, the cohesion of solid matter is greater than that of the other two forms. In the liquid the particles are less firmly bound together and are capable of freer motion about one another. In the gas the mutual attraction of the particles disappears entirely, and their distance from each other depends upon the pressure to which the gas is subjected.

The term fluid applies to both liquids and gases, the former being designated as incompressible, from the very slight degree to which their volume can be reduced by pressure. The gases are designated as compressible fluids t from the fact that their volume can be reduced by pressure to an extent limited only by their passage into the liquid form.

It is highly probable that all substances which are not decomposed when heated are capable of existing in the three forms of solid, liquid, and gas. There are, however, some substances which are only known in two forms — as alcohol, or in a single form — as carbon; probably because we are as yet unable to produce artificially a temperature sufficiently low to solidify the one, or sufficiently high to liquefy or volatilize the other.

The passage of a substance from one form to another is always attended by the absorption or liberation of a definite amount of heat. In passing from the solid to the gaseous form a body absorbs a definite amount of heat with each change of form. If a given quantity of ice at a temperature below the freezing-point of water be heated, its temperature gradually rises until the thermometer marks 0° C, at which point it remains stationary until the last particle of ice has disappeared. At that time another rise of the thermometer begins, and continues until 100° C. is reached (at 760 mm. of barometric pressure), when the water boils, and the thermometer remains stationary until the last particle of water has been converted into steam; after which, if the application of heat be continued, the thermometer again rises. During these two periods of stationary thermometer, heat is taken up by the substance, but is not indicated by the thermometer or by the sense. Not being sensible, it is said to be latent, a term which is liable to mislead, as conveying the idea that heat is stored up in the substance as heat/ such is not the case. During the period of stationary thermometer the heat is not sensible as heat, for the reason that it is being used up in the work required to effect that separation of the particles of matter which constitutes its passage from solid to liquid or from liquid to gas. The amount of heat required to bring about the passage of a given weight of a substance from the denser to the rarer form is always the same, and the t emperature indicated by the thermometer during this passage is always the same for that substance, unless in either case a modification be caused by a variation in pressure. The degree of temperature indicated by the thermometer while a substance is passing from the solid to the liquid state is called its ^f usingpoint/ that indicated during its passage from the liquid to the gaseous form, its boiling-point.

The absorption of heat by a volatilizing liquid is utilized in the arts and in medicine for the production of cold (which is simply the absence of heat), in the manufacture of artificial ice and in the production of local anaesthesia by the ether-spray. The removal of heat from the body in this way, by the evaporation of perspiration from the surface, is an important factor in the maintenance of the body temperature at a point consistent with life.

When a substance passes from a rarer to a denser form it gives out — liberates — an amount of heat equal to that which it absorbed in its passage in the opposite direction. It is for this reason that, while we apply heat to convert a liquid into a vapor, we apply cold to reduce a gas to a liquid. As a rule, the thermometrical indication is the same in whichever direction the change of form occurs; some substances, however, solidify at a temperature slightly different from that at which they fuse.

Most solids, when heated, are first converted into liquids, and these into gases; there are, however, some exceptions to this rule. Solids which pass directly from the solid to the gaseous form are said to sublime.

Divisibility. — All substances are capable of being separated, with greater or less facility, by mechanical means into minute particles. With suitable apparatus, gold may be divided into fragments, visible by the aid of the microscope, whose weight would be -g-oo o o o 1 o o o o o o °^ a g ram j anc ^ it is probable that when a solid is dissolved in a liquid a still greater subdivision is attained.

Although we have no direct experimental evidence of the existence of a limit to this divisibility, we are warranted in believing that matter is not infinitely divisible. A strong argument in favor of this view being that, after physical subdivision has reached the limit of its power with regard to compound substances, these may be further divided into dissimilar bodies by chemical means.

LAWS GOVERNING THE COMBINATION OF ELEMENTS. 7

The limit of mechanical subdivision is the molecule of the physicist, the smallest quantity of matter with which he has to deal.

Elements and Compounds.

If we examine the various substances existing upon and in our earth, we find that many of them can be so decomposed as to yield two or more other substances, distinct in their properties from the substance from whose decomposition they resulted, and from each other. If, for example, sugar be treated with sulphuric acid it blackens, and after a while a mass of charcoal separates. Upon further examination we find that water has also been produced. From this water we may by simple means obtain two gases, differing from each other widely in their properties. Sugar is therefor made up of carbon and the two gases, hydrogen and oxygen; but it has the properties of sugar, and not those of either of its constituent parts. Moreover, if we analyze any number of samples of pure sugar, we will find all of them to contain the same proportionate quantities of carbon, hydrogen, and oxygen (see below). Such a substance as sugar is called a compound.

There exist in nature other substances which it has been impossible, hitherto, to decompose into other dissimilar bodies; such as those are called simple substances or elements.

There are sixty -four elements at present known; but it is probable that, as our methods of investigation are improved, this number will be increased by the discovery of other elements, existing only in small quantities. Indeed, during the past year or two the discovery of elements not included in the above number, scandium, decipium, p>hilippium, and of ytterbium, has been announced.

Laws Governing the Combination of Elements.

The alchemists, Arabian and European, contented themselves in accumulating a store of knowledge of isolated phenomena, without, as far as we know, attempting, in any serious way, to group them in such a manner as to learn the laws governing their occurrence. It was not until the latter part of the last century, 1777, that Wenzel, of Dresden, implied, if he did not distinctly enunciate, what is known as the law of reciprocal proportions. A few years later, Richter, of Berlin, confirming the work of Wenzel, added to it the law of definite proportions, usually called Dalton's first law. Finally, as the result of his investigations from 1804 to 1808, Dalton added the law of multiple proportions, and, reviewing the work of his predecessors, enunciated the results clearly and distinctly.

Considering these laws, not in the order of their discovery, but in that of their natural sequence, we have:

The law of definite proportions, stated in modern language, is that the relative weights of elementary substances in a compound are definite and invariable. If, for example, we analyze water, we find that it is composed of eight parts by weight of oxygen for each part by weight of hydrogen, and that this proportion exists in every instance, whatever the source of the water. If, instead of decomposing, or analyzing water, we start from its elements, and, by synthesis, cause them to unite to form water, we find that, if the mixture be made in the proportion of eight oxygen to one hydrogen by weight, the entire quantity of each gas will be consumed in the formation of water. But if an excess of either have^been added to the mixture, that excess will remain after the combination. This is true of all chemical compounds, and in this we have one distinction between a chemical compound and a mere mixture of two substances; in the former the proportion of the constituents is always the same, while in the latter it is variable. Another distinction between compounds and mixtures is that the former have properties distinct from those of their constituents, and that the properties of these only become evident after decomposition of the compound; while mixtures possess the properties inherent in one or all of their constituents.

The law of multiple proportions, or Dalton's second law, is that when two elements unite with each other to form more than one compound, the resulting compounds contain simple multiple proportions of one element as compared with a constant quantity of the other.

Oxygen and nitrogen, for example, unite with each other to form no less than five compounds. Upon analysis we find that in these the two elements bear to each other the following relations by weight:

In the first, 14 parts of nitrogen to S of oxygen. In the second, 14 parts of nitrogen to 8 x 2 = 16 of oxygen. In the third, 14 parts of nitrogen to 8 x 3 = 24 of oxygen. In the fourth, 14 parts of nitrogen to 8 x 4=32 of oxygen. In the fifth, 14 parts of nitrogen to 8 x 5 = 40 of oxygen.

Finally, the third law, that of reciprocal proportions, is to the effect that the ponderable quantities in which substances unite with the same substance express the relation, or a simple multiple thereof, in which they unite with each other. Or, as Wenzel stated it, " the weights b, b ', b" of several bases which neutralize the same weight a of an acid are the same which will neutralize a constant weight a' of another acid ; and the weights a, a,' a," of different acids which neutralize the same weight b of a base are the same which will neutralize a constant weight of another base b'."

The Atomic Theory.

The laws of Wenzel, Richter, and Dalton, given above, are simply generalized statements of certain groups of facts, and, as such, not only admit of no doubt, but are the foundations upon which chemistry as an exact science is based. Dalton, seeking an explanation of the reason of being of these facts, was led to adopt the view, held by the Greek philosopher Democritus, that matter was not infinitely divisible. He retained the name atom (arop;s:=indivisible), given by Democritus to the ultimate particles of which matter was supposed by him to be composed; but rendered the idea more precise by ascribing to these atoms real magnitude and a definite weight, and by considering elementary substances as made up of atoms of the same kind, and compounds as consisting of atoms of different kinds.

This hypothesis, the first step toward the atomic theory as entertained to-day, afforded a clear explanation of the numerical results stated in the three laws. If hydrogen and oxygen always unite together in the proportion of one of the former to eight of the latter, it is because, said Dalton, the compound consists of an atom of hydrogen, weighing 1, and an atom

Hydrogen.

Oxygen.

25.0

....

14.3

. . . .

• . • •

57.1

72.7

THE ATOMIC THEORY. 9

of oxygen, weighing 8. If, again, in the compounds of nitrogen and

oxygen, we have the two elements uniting in the proportions 14 : 8

14: 8 x 2 14 : 8 x 3 14 : 8 x 4 14 : 8 x 5, it is because they are

severally composed of an atom of nitrogen weighing 14, united to 1, 2, 3, 4 or 5 atoms of oxygen, each weighing 8. Further, that compounds do not exist in which any fraction of 8 oxygen enters, because 8 is the weight of the indivisible atom of oxygen.

One of the chief advantages of Dalton's hypothesis is in the introduction of this precise and simple relation between the quantities of the constituents of a compound. Chemists before Dalton's day, in expressing the results of their analyses, did not progress beyond statements of the percentage composition. Expressing the composition of four of the carbon compounds in percentages, we have:

Carbon.

Marsh gas 75.0

Olefiant gas 85.7

Carbonic oxide 42.9

Carbonic acid 27.3

At first sight, these figures convey nothing beyond the mere centesimal composition of the substances which they express. The cardinal point of Dalton's discovery lies in his translation of them into the simple relations:

Carbon. Hydrogen. Oxygen.

Marsh gas 6 2

Olefiant gas 6 1

Carbonic oxide 6 . . 8

Carbonic acid 6 . . 16

Dalton's hypothesis of the existence of atoms as definite quantities did not, however, meet with general acceptance. Davy, Wollaston, and others considered the quantities in which Dalton had found the elements to unite with each other, as mere 'proportional numbers, or equivalents, as they expressed it, nor is it probable that Dalton's views would have received any further recognition until such time as they might have been exhumed from some musty tome, had their publication not been closely followed by that of the results of the labors of Humboldt and of Gay Lussac, concerning the volumes in which gases unite with each other.