A class-book of chemistry

Front matter

Hhh ;:

Gass.

Book.

Chapter I. Of Some Physical Conditions Of Matter

§ I. Matter and Force, . . . . . . .27

§ II. Gravity and Weighing, ..... 29

§111. Comparative Weight— Specific Gravity, . . . .31

§ IV. Minute Constitution of Matter, .... 35

§ V. Molecular Attractions, . . . . . .38

§VI. Solution, 44

§VII. Crystallization, ....... 46

Chapter II. Chemical Forces, Laws, And Language

§ I. Chemical Attraction, ...... 55

§ II. Laivs of Chemical Combination, . . . . .60

§111. The Atomic Theory, . . . . . 64

§IV. The Nomenclature — Chemical Language, . . . 66

Chapter III. Electricity

§1. General Considerations, ..... 72

§ II. Magnetic Electricity — Magnetism, . . . . .73

i*

10 CONTENTS.

PAGE

§ III. FranHinic Electricity— Electro-Statics, ... 76

§ IV. Voltaic Electricity — Electro- Dynamics, . . . .83

§Y. Effects of Voltaic Electricity, 93

§ VI. Electro- Magnetism, . . . . . .96

§VII. Thermo- Electricity, ...... 98

§ VIII. Animal Electricity, ...... 101

Chapter IV. Heat

§1. Thermal Expansion— Thermometers, .... 103

§11. Nature of Heat, 107

§111. Sources of Heat, 110

§ IV. Conduction and Convection of Heat, . . ' . .114

§ V. Latent Heat— Interior Work, ..... 117

. §VI. Liquefaction — Freezing— Ebullition, . . . .121

§VII. Valorization, . . . ... . . 125

Chapter V. Light — The Radiant Forces

§ I. Movements of Light, ...... 132

§11. The Wave Theory, 135

§ III. Thermal Radiations, . . . . . 139

§ IV. Interference of the Radiants, ..... 148

§ V. Polarization of Light, ...... 150

§VI. Spectrum Analysis, . . . . . .154

§VII. Chemistry of Light, ...... 158

Chapter VI. Mutual Relations Of The Forces

§ I. Connection of Polarities, . . . . . 164

§ II. Connection of the Radiant Forces, ..... 166 r § III. Conservation of Force, ...... 169

Part II. Inorganic Chemistry

ORIGIN OF THE SCIENCE — ALCHEMY.

Chapter VII. The Atmospheric Elements

§11. Ozone — Allotropic Oxygen, ...... 190

CONTENTS. 1 1

PAGE

§ IV. Compounds of Oxygen and Hydrogen, .... 196

§ V. Nitrogen and its Compounds, ..... 206

§ VII. Compounds of Carbon and Oxygen, .... 21S

} VIII. Compounds of Carbon and Hydrogen, .... 221

§ IX. Compounds of Carbon and Nitrogen, .... 225

THE METALLIC ELEMENTS.

§ I. General Properties of the Metals, .... 269

§ II. Theory and Constitution of Salts, ..... 272

12 CONTENTS.

Chapter XIV. Metals Which Decompose Water At Ordinary Temperatures

PAGE

§ I. Metals of the Alkalies, . . . . . ' . 277

1. Potassium and its Compounds, .... 277

2. Sodium and its Compounds, .... 281

3. Manufacture of Glass, ..... 284

4. Caesium— Rubidium— Lithium — Ammonium, . . 287 §11. Metals of the Alkaline Earths, . . . . .289

ORGANIC CHEMISTRY.

Chapter XVIII. Chemical Nature Of Organized Bodies

§ I. Recent Progress of the Subject, ..... 321

§ II. Constitution of Organic Compounds, .... 324

§ III. Colloid Constitution of Matter — Dialysis, . . . 327

§ IV. Organic Analysis, ....... 329

§ V. Theory of Compound Radicles, ..... 332

§ VI. Homologous Series, ....... 833

§VII. Theory of Types, 335

CONTENTS. 13 CHAPTER XIX.

THE SACCHARINE AND AMYLACEOUS GROUP.

PAGE

§1. The Sugars, 338

§111. Woody Fibre, 342

§ IV. Destructive Distillation of Wood, .... 344

§ V. Decay of Wood and its Products, ..... 345

Chapter XX. The Oleaginous Group

§ I. Fats and Fixed Oils, . . . . . .349

§11. The Drying Oils, 351

§111. The Unctuous Oils, ...... 352

§ IV. Volatile or Essential Oils, ...... 354

§ V. Resinous and Waxy Compounds, .... 356

§ VI. Action of Alkalies upon Oils— Soaps, . . . .359

THE

CLASS-BOOK OF CHEMISTRY.

Introduction

ORIGIN AND NATURE OF SCIENTIFIC KNOWLEDGE.

1. In entering upon the study of science, it is desirable that the student should have clear ideas of the origin and nature of the kind of knowledge he proposes to acquire. There is a vague notion among many people that scientific knowledge is of a totally different nature from ordinary knowledge — that science and common sense, if not opposed to each other, are at all events very widely separated. That there is a difference between these two forms of knowledge is true, but it is by no means of the kind usually supposed, and it will repay a little careful attention to learn in what it really consists.

2. Knowledge Progressive.— To understand nature is the prerogative of the human mind, yet this work is so vast and difficult, and its results so precious to humanity, that it is given to no man or to no age fully to penetrate her mysteries. No subject — not the minutest thing — can be so exhausted that further thought and the insight of genius may not discover still deeper meanings aud more subtile relations. And thus the mighty labor becomes progressive; each generation receives its inheritance of knowledge, makes its own additions, and bequeathes the whole to its successor ; so that "We of the present stand as

' The heirs of all the ages in the foremost files of time.'

1. What is stated as desirable for the student of science? What common opinion is referred to ? 2. How does knowledge become progressive ? S. What is

3. Knowledge is thus a growth. It begins in the common information of the uncultivated ; it develops, and in its higher forms it is called science. All the sciences have had their origin in the first rude actions of ordinary minds, and have grown up by slow degrees. Thus the art of counting gradually grew into the science of numbers ; that of land-measuring into the science of geometry. The grouping of the stars into fantastic resemblances of animal forms by the shepherds of old was the germ of Astronomy, while the common facts of combustion, fermentation, and decay, have been slowly evolved into chemical science. But common knowledge does not change its nature in becoming science anymore than does a shrub in becoming a tree, nor can the line be found where one stops and the other begins.

4. A Test of Science. — As the phenomena * of nature take place with perfect regularity, just to the degree in which we understand her ways we can anticipate her results. Science thus confers foresight ; according to its perfection it enables us to foreknow what will take place in the future. Astronomy is the most perfect of the sciences, and hence we are enabled to predict astronomical results with absolute precision thousands of years before they occur. So also with chemistry, just to the degree in which we understand it can we foretell what will take place when certain elements are brought together. This prophetic knowledge or prevision, is the most rigid test of science.

5. Yet the mind of a nursery child answers to this test as well as the intellect of Newton. As has been well observed, even its acquaintance with an apple has in it the rudiment of science. It sees a certain form and color, and it knows if it puts out its hand it will have certain impressions of roundness, smoothness, resistance, and, if it bites, a certain taste. Nor can anything be more certain than the previsions of ordinary minds ; for example, that unsupported bodies will fall ; that water will extinguish fire, and night succeed day. Familiar as these cases are, we see in them the rudiments of

* The word phenomena signifies literally appearances ; they are objects seen or events taking place in the usual course of nature, and not things rare and extraordinary, as is sometimes erroneously supposed.

science ? What is the origin of all sciences ? Examples ? 4. "What power does a knowledge of the order of nature confer? Examples? What is it called? 5. What is said of the knowledge of the child ? Give examples of common previsions. What is said of them ? 6. What example is given of the previsions of

ORIGIN AND NATURE OF SCIENTIFIC KNOWLEDGE. 17

the highest science ; that is, a perfect accordance between the anticipated occurrences and those which actually take place.

6. How Knowledge Grows. — We may trace this element through all the stages of the development of knowledge. A lad knows that the smoke, from the fire he is kindling, will rise; that the fire will consume the fuel and presently warm the room and boil water. These are previsions which he makes just as certainly and accurately as the philosopher.

7. But when the mind begins to inquire, a new class of previsions is reached. It is seen that the fire will disturb the equilibrium of the air and thus cause the smoke to rise ; that an element of the air will enter into chemical union with the fuel ; that there will be no real destruction of matter, but only a change of its forms ; that the chemical action will give rise to heat which will be propagated by conduction through the iron, by circulation through the water, and by radiation through the air. These results are not different in kind from the first — no more positive or certain ; but while the facts and relations in the first case are simple and obvious to the feeblest apprehension, in the latter they are more complex and obscure, and to grasp them requires a higher exercise of reason.

8. But the evolution proceeds still higher ; at first there is only certainty ; at last there is exactness. First the hind* of effect are foretold, and then their amount. The weight and pressure of the air, the rate of its expansion by heat, the amount of its ascensional force, and how much the chimney retards by friction, are precisely determined ; and the consequent power of draft is predicted. Xot only that oxygen combines with the fuel, but exactly how much will be required to consume it, what quantity of heat will be generated, how much water boiled, and space warmed, are finally foretold. In its completest form Science advances to measurement : it first determines qualities, then quantities.*

9. Thus is common knowledge constantly rising into the higher and more perfect form of science ; its tendency is ever from the im-

* For an able exposition of the doctrine here glanced at, the student is referred to a paper in Herbert Spencer's Essays, entitled ' The Genesis of Science.'

ordinary knowledge ? 7. What higher previsions may arise from these ? "What is the difference between them ? 8. What others are mentioned in the third stage of evolution? Give illustrations. 9. What is said of the mental operations which mediate to the remote, from the loose and vague to the definite and exact. If now we examine those mental operations by which knowledge is developed we shall find them to be one and the same in all the degrees of its evolution. Mind acts according to its necessary laws, which are identical in the child, the adult, and the most advanced philosopher.

10. Observation. — By the impressions produced upon the senses our attention is constantly solicited to the objects around us, and the giving of this attention is called observation. This is the basis of experience and the first condition of all ordinary knowledge. The person who carefully remarks the conduct and appearance of people, giving attention to their peculiarities and differences, is called an ' observer of human nature.' And so the agriculturist who notes whatever pertains to soils, stock, fruits, &c, is known as an 'observing farmer.'

11. Science also begins exactly here; its basis is observation. But the hasty and careless observations of people in the ordinary affairs of life, where appearances are constantly misinterpreted and everything is seen in the light of preconceived ideas, would be a very insufficient foundation for science. Its first step, therefore, is to educate this faculty by a systematic discipline. Observation is not mere looking or listening ; it is discrimination. It is the eye of reason that observes. For purposes of science observations must be made with patience and caution ; numerous sources of error from without and within — sources of which people generally are entirely unconscious — have to be vigilantly guarded against, or the results are worthless.

12. Experiment.— Here again we commence with the ordinary experience of mankind ; everybody makes experiments. "We wet, heat, scratch, bend, press, and tear substances to test their qualities. We try the fastness of colors by washing a fabric, and the genuineness of coin by its sonorous ring. But what is thus begun and practised in a rude way by everybody, science improves and carries out in a systematic manner. Its cultivators not only passively observe, but, with hand and instrument, in a thousand ways they put nature to direct trial. Objects are placed in as many different conditions as the operator's ingenuity can contrive,

produce science? 10. What is observation? Mention common instances. 11. What is the basis of science ? How does scientific differ from common observation ? 12. What examples are given of common experimenting ? How does

ORIGIN AND NATURE OF SCIENTIFIC KNOWLEDGE. 19

and the changes noted and compared. Only by this assiduous cross-questioning of nature by thousands of investigators has our knowledge of her laws been enlarged in extent and increased in exactness until it has reached its present advancement.

13. Diversity of Natural Objects. — The objects and operations of nature with which observation acquaints us are innumerable. Each region of the earth produces its peculiar forms of life ; each tree has its own appearance ; each leaf its peculiarity ; each animal its distinguishing marks ; each stone its individual features. No two faces, no two blades of grass, and, as the microscope shows, no two grains of sand are precisely alike. So also with the occurrences of experience. No season is like its predecessor ; no day repeats another ; no event is ever exactly reproduced.

14. Abstraction, Generalization, Classification.— This vast multiplicity of objects and events would confuse anct confound the mind if it attempted to grasp or remember them all. The facts must be grouped or bound together in bundles before the mind can command them for purposes of general knowledge. Observation accumulates individual facts ; the mind then searches for some point or quality in which a great number of objects agree, and having found it, gives them a common name. Thus all animals having a spinal column were grouped together as vertebrates ; all trees which grow by the successive addition of external layers as exogens.

15. As this act of the mind puts aside those particulars in which objects differ, and separates or abstracts those of resemblance, it is called a process of abstraction: as it is a passing from particulars to generals, it is called generalization; while this sorting of a multitude of things into parcels for the sake of knowing them better and remembering them more easily, is called classification.

16. But this is no peculiarity of science, for all minds inevitably proceed in the same manner. Were a basket of fruit placed before a child, it would very naturally separate and group together the apples, the pears, and the plums ; it would therefore perform the operations of abstraction, generalization, and classification.

science improve upon this ? What is the result ? 13. What is said of the diversity of natural objects ? 14. What would be the effect of trying to remember them all ? What has to be done 1 Examples. 15. What is abstraction ? Generalization ? Classification? 16. What familiar examples are offered ? 17. Describe the ill us-

20 LNTTKODUCTION.

Were the chemical elements placed before it on a table, it would also naturally separate all the shining metals from the rest, and thus take the first great step in chemical classification. Those mental operations which are practised by everybody in an unconscious and imperfect way, give rise at length, by culture and discipline, to comprehensive scientific methods.

17. Induction. — This term denotes an essential operation of the mind, by which knowledge is acquired, and which is just as well exemplified in every-day experience as in the highest efforts of thought. For example, you place a piece of oak wood in the fire, and it burns ; you then put pieces of maple, pine, and mahogany in the fire, and they also burn. From these facts you gather the general principle that all wood will burn. This is called an induction, from induco, to lead m, and signifies the bringing in of one fact after another to establish a general truth. It is true there are thousands of varieties of wood, and you have tried but three or four ; yet from your experience of nature you conclude that what is true in certain cases will be true in all similar cases. If you observe in a larger number of instances that wood burns, the induction is strengthened.

18. Deduction. — If now you meet with a new variety of wood, you immediately think in the following manner, which is called a syllogism : All wood is combustible ; this substance is wood, and therefore it will burn. In this case you take the induction as a general principle, and apply it in a particular case. This is deduction, from deduco, to lead down, and signifies the descent from a universal truth to a special application. Thus induction discovers principles, while deduction applies them.

19. Verification is testing the truth of a conclusion. Should you hear various persons from different parts of the world assert that they have tried many kinds of wood, and find that they all burn, you would say this is an experimental verification of the law. Or if a chemist should say, I have analyzed many kinds of wood, and find that they all consist of the same combustible elements ; other chemists obtain the same results with other sorts, and as the mode of vegetable growth and the essential constituents of plants are everywhere the same, all wood must be combustible, you

tration of induction. What does the word signify ? What is its basis? 18. If a new kind of wood is met with, how does the mind proceed ? What is deduction ? 19. What is verification ? Describe the experimental and theoretical verifications.

OEIGIN AND NATURE OF SCIENTIFIC KNOWLEDGE. 21

would look upon this as a theoretical verification of your law. You would further say, this principle is true, because it may be verified by anybody at any time.

20. The grandest discoveries in science are made in precisely the same way. The master minds of our race, by a course of toilsome research through thousands of years, gradually established the principles of mechanical force and motion. Facts were raised into generalities, and -these into still higher generalizations, until at length the genius of Newton seized the great principle of attraction, which controls all bodies on the earth and in the heavens. He explained the mechanism and motions of the universe by the grandest induction of the human mind.

21. The mighty principle thus established now became the first step of the deductive method. Leveerier, in the solitude of his study, reasoning downward from the universal law through planetary perturbation, proclaimed the existence, place, and dimensions of a new and hitherto unknown planet in our solar system. He then called upon the astronomer to verify his deduction by the telescope. The observation was immediately made, the planet was discovered, and the immortal prediction of science was literally fulfilled.

22. Hypothesis. — This is a supposition or guess put forth to account for any occurrence or state of facts. For example, a boy misses his knife. Various conjectures go rapidly through his mind as to the cause of its disappearance. He may have mislaid it, left it in another pocket, or it may be lost, lent, or stolen. Each of these ideas involves a hypothesis of the loss of the knife. These he proceeds to test one after another ; he examines his pockets, searches in various places, inquires of his companions, but cannot find it ; that is, each of his hypotheses fails when he attempts to verify it. At length, perhaps, it is found upon a comrade under circumstances which establish the hypothesis of its theft. Thus hypotheses, instead of being the mere fine-spun fancies of unpractical thinkers, as is too commonly supposed, are employed every day by everybody as the only guides of conduct and action. Literally a hypothesis signifies a supposition placed under the facts as a platform to support them.

20. What example is given of scientific induction ? 21. How was it applied deductively ? How verified ? 22. What is a hypothesis ? Describe a familiar use of hypothesis. Of what essential use are hypotheses? 23. What is the literal

23. All scientific inquiry begins in the same manner with guesses. The facts being observed, various conjectures or hypotheses are made to explain them. It cannot be denied that in science, as in common life, there are various aptitudes for making hypotheses which no precepts can teach. It depends largely upon boldness of thought and fertility of invention ; upon an original cast of the intellect — the questioning temper — the busy, suggestive mind — the piercing glance of genius, which sees what others overlook, which prizes what others neglect, which takes its flight beyond rules, and is a law to itself.

24. Insufficiency of Hypothesis. — But it is not by skilful conjecture that knowledge grows, or it would have ripened thousands of years ago. It was not till men had learned to submit their cherished speculations to the merciless and consuming ordeal of verification that the great truths of nature began to be revealed. Kepler tells us that he made and rejected nineteen hypotheses of the motion of Mars before he established the true doctrine that it moves in an ellipse ; and Dr. Faraday remarks : ' The world little knows how many of the thoughts and theories which have passed through the mind of a scientific investigator have been crushed in silence and secrecy by his own adverse criticism.'

25. Theory means literally a view. It is an accepted hypothesis ; an explanation of phenomena. For example, the principles which explain the structure and movements of a watch form the theory of the watch. It is common to contrast theory with practice, disparaging the former and commending the latter ; but this is erroneous. Theory is derived from practice ; indeed, it is a knowledge of the principles by which practice accomplishes its end. ^

26. Cause and Law. — Any agency which produces an effect, and which when known explains it, is termed its cause; while the manner in which the force acts in producing the effect is termed its law. Thus the cause of the fall of a stone is the force of gravitation, while the conditions under which the power acts is called its law ; viz., that bodies attract each other with a force directly proportional to their respective masses and inversely as the square

meaning of hypothesis 7 "Where does scientific inquiry begin ? Upon what does skill in making hypotheses depend? 24. What beside hypothesis is necessary * to denote science ? What is said of Kepler ? What does Faraday observe ? 25. What is a theory ? How is it related to practice ? 26. What is a cause ? What

ORIGIN AND NATURE OF SCIENTIFIC KNOWLEDGE. 23

of their distances. The cause of chemical combination is the force of affinity ; the law of the force is that bodies combine in definite and constant proportions. Strictly speaking, that which invariably precedes an act, its antecedent or several antecedents, constitutes its cause ; while such an expression of the condition in which the power acts, or the event occurs, as enables the result to be determined beforehand, is known as the law.

27. We may call the first conjecture of universal attraction in the mind of Xewton, which he believed probable, but held in suspense for many years, an hypothesis. But when important facts which apparently contradicted the hypothesis were revised and found to agree with it, it assumed the character of a theory, and as such it was on trial for a hundred years, until the greatest mathematicians, clearing away difficulty after difficulty, demonstrated it to be a universal law.

28. Empiricism ordinarily signifies mere pretension and quackery, but in science it denotes the results of observation just as they are obtained, before they are reasoned upon or reduced to principles. Empirical results of inquiry are the naked facts without any theorizing or attempts to explain them.

29. Science and Art. — As science represents the later stage of knowledge, art represents the earlier. Men first, through painful toil, servile imitation, and blind rules, learned what to do ; then came the question ichy it was done, and the advance was made to theories and explanations, or science. Art is therefore empirical, science rational ; art asks for rules, science for reasons ; art is an affair of practice, science of principles and causes. The first is the root, the latter the outgrowth. The arts and sciences mutually help each other forward. Art presents to science her difficulties ; science solves them, and, while thus increasing her own stores of truth, returns to art principles for her better guidance.

30. Why Science is so Recent. — For thousands of years the race lingered in the early or art-period of knowledge. This was not for lack of intellectual activity, but from its misapplication. The ancient philosophers, disdaining nature, retired into the ideal world of pure meditation, and holding that the mind is the meas-

a law? Examples ? 27. What example is there of the growth of a hypothesis to a theory and how ? 28. "What is empiricism ? 29. "What are the relations of art and science ? "What did men first learn ? How are science and art constructed ? How do they help each other ? 30. "What was the state of mind of the ancient ure of the universe, they believed they could reason out all truths from the depths of the soul. Despising matter, they were not drawn to observe and study ifc ; despising labor as menial and degrading, they would not experiment ; consequently they lacked the first conditions of science, Observation, Experiment, and Induction. They reasoned from fanciful notions to worthless conclusions, and the intellectual power of ages was thus wasted. Genius spent itself in beating the air ; the philosophers wrestled with shadows ; they chased each other round the circles of verbal disputation, they pursued the rainbow, disdaining the priceless gems which abound in the earth beneath. It was the period of inexperience, and their mistake was perhaps natural, but it was an error that paralyzed the world. The first step of progress was impossible. There was no conquest of nature or liberation of man from the drudgeries of endless toil ; no spirit of general inquiry, no projects of education or hope of improvement.

31. Succession of the Sciences. — Thus the sciences do not rise or advance together ; they have appeared in succession — the earlier, as it were, preparing for the later, and the later springing out of the earlier. Man was first impressed by the beautiful regularity of the celestial motions ; they excited his wonder and aroused his thought ; and hence Astronomy is the oldest of the sciences. Then the visible movements of earthly bodies were also found to be governed by invariable laws, and Mechanical science was the result. The human mind having now established the idea of order in the heavens and on the earth, it was next found that the deeper changes which go on within material objects, altering their nature and properties, are also of an invariable character; and then appeared the science of Chemistry ; and when, still later, the same thing was perceived in living beings, there arose the science of Physiology.

32. Many subjects are now in the rudimental condition of common knowledge which are yet to assume the scientific form, while some are capable of only a partial development. Science furnishes the only true method of their study, while yet they are so complex that the human mind may never be able completely to analyze them For example, Commerce, Education, Society, and

philosophers? "Why did they fail in science? What was the consequence of their attitude of mind ? 31. In what manner have the sciences appeared ? In what order ? 32. In what condition are many subjects at present ? What is said of

ORIGIN AND NATURE OP SCIENTIFIC KNOWLEDGE. 25

History are not properly to be considered as sciences ; yet the operations of business, the culture and growth of mind, the social relations of men, and the course of the world's events, inasmuch as they all unquestionably involve fixed principles and the action of uniform causes, must become more and more scientific in the method of their treatment.

33. Claims of Science. — The idea thus briefly illustrated, that knowledge is by its very nature progressive — that it grows into the higher form of science through the education of the essential faculties of the common mind — is of the deepest significance in education. We see that science is not a mere curious and profitless prying into the obscure recesses of nature, nor a rigid system of thought inapplicable and worthless in the walks of common experience. On the contrary, it is a result of the mind's normal growth — a product and proof of its completest discipline. By a gradual transition we rise from the obvious and simple to the remote and complex ; the same faculties being called into progressively higher and more systematic exercise in the ascending course of scientific inquiry.