Principles of chemistry: embracing the most recent discoveries in the science, and the outlines of its application to agriculture and the arts ...

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Preface

In the revision and enlargement of the " Principles of Chemistry," the Author has made it his especial care to retain those peculiar features of the work to which it owes its distinctive character as a text-book, and which have secured for it, among teachers, such wide approval.

Especially designed for beginners in the science, whether in schools or colleges, great effort was made in the original volume to simplify the study of Chemistry, and to save teachers much explanation which would otherwise be required. To this end, the facts were more carefully classified than is usual, many details of interest only to the professional chemist were omitted, great simplicity of statement was uniformly observed, and chemical phenomena were described in ordinary, as well as in symbolic language. In pursuance of the same general design, a large number of experiments were devised, of the utmost simplicity, extending over a wide field of the science, and bringing the illustration of the subject within the reach of every

IV PREFACE.

pupil. A series of new and original designs were also introduced, illustrating to the eye the * groupings of organic chemistry. All of these characteristic features have been retained in the revised edition.

While a new class of cuts have been introduced, illustrative of lecture experiments, and adapting the book more completely to college use, all of the more simple experiments with the figures describing them, have been preserved in the present edition. This course has been pursued, first, because of the great advantage which it gives to the student, who with limited means at his command, still entertains the ambition to become an experimenter, and secondly, because the figures referred to, serve, in proportion to their simplicity, as object-lessons of the most effective character, and take the place of experiments where the experiments themselves cannot be performed. This is, however, according to the testimony of teachfers, but a small part of the end which they serve. The reduction of the experiment to its very simplest form is found to simplify greatly to the learner the apprehension of the subject which it illustrates.

In pursuance of" the leading object of the revision, viz., to bring the work up to the present condition of the science, considerable portions have been entirely rewritten, and every page carefully revised.

The Chapter on Animal Chemistry has been so expanded as to include a presentation of the more interesting topics in Human Physiology, and will be found

PREFACE. V

amply illustrated by cuts introduced for the first time in this edition.

The revision has necessarily resulted in a considerable enlargement of the work, and it will now be found to contain quite as extensive a survey of the science of Chemistry as can with advantage be pursued in an ordinary college course.

So large a number of authorities have been consulted in the preparation of the new edition, that special acknowledgment of each cannot be attempted.

The author would, however, express his especial indebtedness to the articles of Professor Graham, on " Crystalloid and Colloid Substances, 5 ' and to Professor

Tvndall's lectures on " Heat considered as a Mode of

Motion." It has not been deemed advisable to modify the language employed in the Chapter on Heat, or the mode of presenting the subject, in view of the recent more perfect development of the dynamical theory. To carry out any such purpose consistently, would have been impracticable, inasmuch as the new theory has not as yet provided itself with an adequate vocabulary.

It has been deemed the wiser course to hold strictly to the material theory in the description of phenomena, and the statement of principles, and to indicate in connection with each important topic the difference of conception which the dynamic theory requires.

It remains for the author to express his great obligations to Dr. M. C. White, of New Haven, and Professor Seely, of Middlebury College, for important aid

VI PREFACE.

rendered in the revision of this work. He would also embrace this opportunity of expressing his acknowledgments for the favorable reception accorded to former editions of the work, and his hope that the effort to make the present revised edition still more worthy of approval, may not have been altogether unsuccessful.

JOHN A. PORTER.

Part I. Physics

PAGE

Atoms and Attraction, T

Three States of Matter ; Contact of Atoms, 10

Light. — Chemical Action of Light, 11

Theories of Light, 12

Laws of Light, 14

Reflection, 16

Refraction, 18

Analysis of Light, 22

Spectral Analysis, 25

Heat. — Nature and Sources, 26

Communication of Heat ; 32

Changes effected by Heat, 55

Expansion, 58

Liquefaction, ?1

Vaporization, 76

Boiling, 89

Mechanical Equivalent of Heat, Ill

Correlation of Forces, 149

Part II. Chemical Philosophy

Laws of Combination.

Number of Elements, 151

Atomic Constitution, 151

Vlll TABLE OF CONTENTS.

PAGE

Explanation of Symbols, 153

Chemical Equivalents, 15*7

Properties of Acids and Bases, 160

Effects of Solution, 161

Electrical Kelations of Elements, 161

Part III. Iintoirg^ajntic Chemistry

Non-Metallic Elements.

Classification of Elementary Bodies, 163

Iodine, 181

Bromine, - 184

Eluorine, 185

Nitrogen, 200

Arsenic, 217

Silicon, . . 244=

Boron, , 246

Incandescence, 294

Color of Flame ; Spectra of Metals, 296

Metals. — Physical Properties of Metals, 299

Classification of Metals, 301

Class i. — Potassium, &c, 303

Class ii. — Barium, &c, 310

Class iil — Aluminum, Manganese, Iron, &Cy .312

Class iv. — Tin, Antimony, &c, 326

Class v. — Bismuth, Copper, &c, 331

Class vi. — Mercury, Silver, Gold, &c, 339

Salts. — Solution and Crystallization, 362

Variety of Crystals, 372

TABLE OF CONTENTS. ix

PAGE

Systems of Crystals, 374

Isomorphism, -. 377

Oxides, 378

Fluorides, 398

Sulphurets, 398

Phosphates, 416

Borates, 427

Chromates, 428

Manganates, „ 430

Part IV. Oirg^ajstic Chemistry

General "Views, 441

Vegetable Chemistry, 460

Growth of Plants, 460

"Wood and its Products, 467

Starch, 487

Sugar, 493

Organic Acids, 511

Organic Bases, 524

Essential Oils and Resins, 526

Protein Bodies — Putrefaction, 538

Permentation — Bread Making, 541

' Coloring Matters, 548

Dyeing, 549

Calico Printing, 552

Agricultural Chemistry, 554

Animal Chemistry 564

X TABLE OF CONTENTS.

PAGE

Smee's Battery, 60?

Groves' Battery, 607

Ruhmkorff Coil, 608

Atomic Theory, 609

Specific Gravity, 611

Atomic Heat, 612

Estimating the Value of Guano, 616

Physical Tables, 61?

Linear Expansion of Solids, 61?

Specific Heat, 61?

Melting Points of Solids, 61?

Boiling Points of Liquids, 618

Composition of Human Blood, 618

Composition of Cow's Milk, 618

Proportions of Sanguineous and Respiratory Food, 619

Amount of Alcohol in Spirituous Liquors,. . » 619

Solubility of Substances in Water and Acids, 620

Homologous Series of Organic Acids, 622

Composition of Ashes and Common Crops, 622

List of Chemicals and Apparatus, 631

Introduction

According to the most ancient view of the constitu* tion of matter, the earth and all material things are but modifications of one and the same original substance. Fire, "water, and air, were each in turn asserted to be the primitive element, according to the arbitrary conjecture of philosophers who w^ere bold enough to speculate upon the subject. At a later date, the views of all seemed to be harmonized in ascribing the same dignity to the three contending elements, and including earth among the original varieties of matter. Earth, Air, Fire, and Water, were assumed to be the original materials out of which all forms of matter are produced.

Modern chemistry has dethroned each of these elemental monarchs of the world, and distributed their prerogatives among a larger number. Earth, ah*, and water, are all excluded from the list of elements, and fire appears in the modern view as only the transient attendant of chemical combination.

INTRODUCTION.

Each one of the acknowledged elements has its own specific properties, affinities, and capacity of combination. These peculiarities, and all resulting phenomena, it is the province of chemistry to investigate and explain. Light, heat, and electricity, stand in intimate relation to all chemical action, either as cause or effect, or unfailing attendant, and are, therefore, briefly considered in the earlier part of the present work.

The study of science has not for its object the mere gratification of an idle curiosity. Looking at the subject from a material point of view alone, chemistry is one of the great agents in the transformation of nature, and its subjugation to the wants of man. The earth yields her treasure to its skillfully conducted processes, and even the trodden clay becomes converted in its crucible into shining metal. The arts draw from it, with every succeeding year, increased advantage, and the condition of mankind is elevated, and the world advanced by its progressive triumphs. Agriculture also is indebted to its discoveries. It opens to us mines of agricultural wealth in what w^ould otherwise have passed for worthless refuse. It clothes exhausted fields with new fertility, by the addition of some failing constituent whose absence its subtle processes have detected. It carefully investigates the laws and conditions of vegetable growth, by which earth and air are

INTRODUCTION. 3

converted into food for man and beast, and thus places ns on the highway of sure and rapid improvement.

These practical results, which are the basis of that material prosperity in which taste, and literature, and the graces of life find their natural growth, are by no means to be disregarded. But this is not all. The study of chemical science reveals to the mind a beauty and harmony in the material world, to which the uninstructed eye is blind. It shows us all of the kingdoms of nature contributing to the growth of the tiniest plant, and feeding the nascent germ, by the inter-revolution of their separate spheres. It shows us how through fire, or analogous decay, all forms of life are returned again to the kingdoms of nature, from which they were derived. "Without encroaching upon the domains of the astronomer, it reveals to us still more wonderful relations of distant orbs, which affect not only the outward sense, but supply the very forces which we employ in our contest with the powers of nature. It unveils to us a thousand mysteries of cloud and rain, of frost and dew, of growth and decay, and unfolds the operation of those silent yet irresistible forces which are the life of the world we inhabit.

But the study of nature is worthy of being pursued with a still nobler aim. The glory of the Deity shines in every crystal and blooms in every flower. Every

4 INTRODUCTION.

atom is instinct with a life which the Creator has imparted. The laws that govern the minutest particles, as well as the grander revolutions of the heavenly spheres, are but the expression of His will. The reverent study of nature is therefore a contemplation of Deity. Vague and unsatisfactory without the aid of another, and written revelation, it unfolds to the mind thus enlightened, new and exalting evidences of the infinite wisdom and "beneficence of the Creator of the world.

INTRODUCTORY.

L The Science of Chemistry is of the widest range. Air, Earth, Fire, and Water, all belong to its domain.

It informs us of the composition of the rocks which make up the mass of the Earth, and of the soil which forms its surface. It tells us of what Air is made, and how it supplies the wants of animal and vegetable life. It separates "Water into gases, and reproduces it again by uniting them. It informs us of the nature of Eire, and of the changes which take place in combustion.

2. It tells us of what plants are formed, and what becomes of them when they decay and disappear. It tells us how to produce metals from ores, wines from fruit, liquors from grain, and shows us the changes which take place in the formation of all these substances. Almost all transformations which occur in the materials around us — as, for example, of iron into rust, of wood or coal into gas, of food into flesh — it belongs to Chemistry to describe and explain.

Questions. — 1. What does Chemistry tell us of earth, air, fire, and water ? 2. What of metals, plants, and wines ?

6 INTRODUCTORY.

3. As all of tliese changes result from the action of the minute particles of matter on each other, it is necessary first to consider the subject of Atoms.

4. As the most of them depend on changes of temperature, it is necessary, in the first part of the work, to consider the laws and effects of Heat. As these laws are best understood from their analogy to the laws of Light, and as Light has an important influence in many chemical processes, a brief chapter on Light precedes the chapter on Heat and its various effects.

5. As many, and perhaps all chemical changes, are accompanied by electrical phenomena, it is also important to dwell briefly on the subject of Electricity before proceeding to what is more strictly the science of Chemistry. The first part of this work is, therefore, devoted to the consideration of these subjects; or, in other words, to the Science of Physics.

3. Why does it treat of atoms ? 5. Why of heat and light ? 5. Why is electricity introduced ?

Chapter I. ^.toms ^zstid Attraction

1. Atoms. — All matter is supposed to be composed of exceedingly minute spherical or spheroidal particles, which are held together by their mutual attraction, and are never themselves subdivided. These particles are commonly called atoms. There is reason to believe that the atoms of different substances differ from each other in weight and perhaps in size. The belief that they are never subdivided is not based on their extreme minuteness, but on other grounds, to be mentioned hereafter.

2. Minuteness of Atoms. — Their minuteness is illustrated by the fact that a single grain of musk will fill a room with its fragrant particles for years, without suffering any considerable loss of weight. The number of atoms it gives off during that time is beyond computation.

Questions. — 1. Of what is matter composed ? What is said of atoms ? . How is the minuteness of atoms shown?

3. Elements. — There are at least sixty different kinds of matter. Eacli kind which cannot be separated into other kinds is called an elementary substance, or simply an element. Iron and carbon or charcoal are elements. Iron rust, on the other hand, is a compound. There are, of course, as many different kinds of atoms as there are of elements.

4. Cohesion. — The force which binds together atoms of the same kind is called the attraction of cohesion, or simply cohesion. In the more tenacious substances, such as iron or copper, the force of cohesion is immense. The strength of a horse is insufficient, for example, to break an iron wire one-fourth of an inch in thickness, because in every section of the wire the atoms attract each other with a superior force. As we may imagine innumerable sections in every inch of the wire, we see that there is in every inch a force of attraction exerted, which in its sum total is inconceivably great. Attraction between unlike atoms in contact with each other, as between glue and the wood to which it is applied, is called adhesion.

5. Gravitation. — Unlike the force of attraction mentioned in the preceding paragraph, gravitation is an attractive force which acts at all distances. The weight of all bodies is due to gravitation; one body weighs twice or three times as much as another, because it has twice or three times the quantity of matter to attract and be attracted by the earth.

3. Define and illustrate an element ? 4. What is cohesion ? Illustrate the subject ? What is adhesion ? 5. How does gravitation act ?

ATOMS AND ATTRACTION. 9

The attraction of gravitation causes terrestrial bodies to fall to the earth, and the same force extending to celestial bodies retains the planets in their orbits.

6. Chemical Attraction, or Affinity. — The force which unites unlike atoms to form compounds possessing new properties is called chemical attraction, or affinity. Thus iron and oxygen unite by chemical attraction to form iron rust, a substance different from either. The gas chlorine and the metal sodium unite, as will be hereafter seen, to form common salt. When substances become thus united by chemical affinity, the resulting compound is not a mere mixture, with properties of both constituents, as when salt and sugar are mixed ; it is, on the contrary, a new substance, with properties of its own.

7. Distance of Attraction. — The forces of attraction above mentioned, with the exception of gravitation, act only at immeasurably small distances. The attraction of two plates of glass, an inch apart is too feeble to be perceptible, and when brought into apparent contact they exhibit but little cohesive attraction. But if two plates of glass, well polished and perfectly clean, are pressed together with great force, the atoms are brought within the range of cohesive attraction, and they unite so firmly that fracture takes place in any other direction quite as readily as in the line of union. So iron and oxygen will not attract each other

6. What is chemical attraction or affinity ? 7. Do the forces of cohesion and chemical affinity act at great distances ?

from a distance, but when brought together, they unite in consequence of their chemical attraction.

8. The three kinds of attraction are perfectly illustrated in a falling drop of water. Affinity holds together the atoms of oxygen and hydrogen which make up each particle of water. Cohesion unites the particles of water thus formed, to make the drop, and gravitation causes the coherent drop to fall.

9. Three States of Matter. — There are three distinct states or conditions of matter — the solid, the liquid, and the gaseous. Almost all substances may be made to assume each of these states. Thus, a piece of solid sulphur, if heated up to a certain point, melts and becomes liquid. If the liquid sulphur be exposed to a still higher temperature, it passes off in the form of a vapor or gas.

10. Contact of Atoms. — The atoms of matter are not supposed to be in absolute contact in either solids, liquids, or gases. This is inferred from the fact that all substances may be diminished in bulk by pressure. But in solid bodies the attraction of cohesion between the atoms is strongest, and they are more nearly and firmly bound together. In liquids, cohesion is less than in solids, and the atoms are free to roll and glide around each other. In gases, cohesion is entirely overcome, and but for gravity, the atoms would separate themselves indefinitely.

8. Illustrate the three different kinds of attraction. 9. What are the three states of matter ? 10. Are atoms in contact ? What is the cause of the difference of cohesion in bodies ?

Heat is the main cause of this difference in cohesion. This subject will be more fully considered in the chapter on Heat, or Caloric*

Chapter II

11. Light is the Soukce of Yision. — We ascribe the phenomena of vision, by which we obtain our principal knowledge of the material world, to a mysterious agent called light.

12. Chemical Actiox of Light. — Daguerreotype pictures are produced by the chemical action of light. So, light acts chemically in converting water and the carbonic acid of the air into vegetable matter. The action of light in these cases will be explained hereafter. The present chapter is devoted to the consideration of its nature and more important laws.

13. Light is without Weight. — While the effects of

11. To what agent do we ascribe the phenomena of vision? 12. In what cases does light act chemically ? 13. Has light weight ?

* The subject of Crystallization belongs to Physics, and in a strictly scientific arrangement, would be considered in this place. The student will find the most convenient illustrations of this subject in the Salts, which are considered later in the work, and it has therefore been introduced in the chapter which treats of these compounds. It is to be borne in mind that what is there said of crystallization, relates to other compounds and to elementary substances, as well as to salts.

light, and the laws according to which they take place are well understood, philosophers have differed widely with respect to its nature. It is, however, agreed that light is imponderable, or without weight, this being inferred from the fact that an illumined object weighs no more than the same object when unillumined.

14. Newton's Theory. — Newton maintained that light is a material substance, thinner or more subtle than air, or any gas, but composed, like these, of minute particles, constantly given off from the sun and all luminous objects. He supposed that it is this substance passing into the eye that produces the sensation of sight, as the fine particles of fragrant matter, passing off from flowers, produce the sensation of smell.

15. Undulatory Theory. — Another view is that a very subtle fluid pervades all space, and serves as a medium for producing the sensation of light, as the air does for producing sound. This view is now generally accepted.

16. When a bell is struck its vibrations are communicated to the air, and thence to the ear, producing the effect of sound. So, according to the undulatory theory of light, vibrations are caused by some means in the sun and certain other bodies, which being rapidly transmitted through the fluid above mentioned, produce, when they fall on the eye, the sensation of light.

17. Existence of the supposed Fluid. — Such a fluid

14. What was Newton's theory ? How is the sensation of sight produced ? 15. What is the other view of the nature of light ? 16. Illustrate this view. 17. How is this fluid known to exist ?

as this theory requires is known to exist in the spaces between the heavenly bodies, by the influence which it exerts on their motions, and is supposed to pervade all substances, whether solid, liquid, or gaseous, occupying the spaces between their particles. It is called ether, but has no relation to the chemical and medicinal liquid of the same name.

18. For the explanation of the leading phenomena of light, it matters little which of the views above mentioned is adopted. Thus, in the study of the laws of reflection, it matters little whether we regard light as a subtle fluid whose particles rebound from polished surfaces as a ball does when thrown against a house, or whether we suppose it to consist of ethereal vibrations which take a new direction from impact upon certain surfaces, as do the vibrations of the air in the case of echoes.

19. The definitions and laws of light are stated in the language of the Newtonian theory, because they are thus more easily understood. We employ this language without adopting the theory, just as astronomers say that the sun rises and sets, though it is well known that the sun is fixed in the heavens, while the earth revolves on its axis from west to east once in twenty-four hours.

20. Ray, Pencil, Beam, and Medium, defined. — Light moving in a single line is called a ray of light,

IS. How does either view explain reflection ? 19. Which theory is used in stating the laws of light ? Why ? 20. What is a ray of light ? a pencil of light ? a beam of light ? a medium ?

PRINCIPLES OF CHEMISTRY.

In such rays or lines light is constantly passing off from all visible objects. From every part of the book before the student, for example, it passes into the eye, enabling him to know the nature of the object. If the book is taken into a dark room it is no longer visible, because it obtains no light which it may afterward reflect to the eye. A collection of rays proceeding from a point is called a pencil of light. A collection of rays moving in lines parallel to each other is called a beam of light. Rays of light coming from the sun are parallel, while rays from a lamp or candle come to us in pencils of diverging rays. A medium is any space or substance through which light passes.

21. Laws of Light. — The more important laws of the radiation of light are the following :

l. 1. Rays of light proceed from

every point of luminous objects in every direction. They proceed, for example, from every point of the sun's surface.

2. They proceed in straight lines.

Light, for example, comes to us in straight lines from the sun.

3. They diverge as they proceed. This is illustrated in the figure, the central point being supposed to be a star, or other source of light.

22. Divergence of Light. — By the divergence of rays of light is meant that they spread themselves over

21. Give the laws of light ? 22. Explain the divergence of rays of light?

LIGHT.

more space the further they proceed from their source. This is illustrated in the figure, where the light of a candle is represented as passing through a window, and illuminating a larger space on the opposite wall.

23. Law of Divergence. — When the distance is doubled, the surface that light will cover is quadrupled. This is also illustrated in the figure. The wall being twice as far from the candle as the window, the light covers four times the surface. If the distance of the wall were three times that of the window, the surface covered would be nine times as large as the window ; if four times, the surface covered would be sixteen times as large. It is evident from these figures that the surfaces covered increase as the squares of the distances. The light, of course, diminishes in intensity in the same proportion, as it is thus spread over greater surface. At four times the distance, it has only one-sixteenth the intensity, and so on.

If a square board is placed at a distance of one foot, and a screen at the distance of two

feet from a candle, the shadows on the screen will cover a space four times as large as the board which intercepts the light. If the screen is at the distance of

23. Give the law of divergence, and illustrations ?

three feet, the shadow will be nine times as large — that is, three times as broad and three times as high, and multiplying the breadth by the height, we see that the space covered by the shadow increases as the square of the distance as shown in the figure.

24. Reflection of Light. — If a ball of ivory or other material is thrown perpendicularly against any hard plane surface, it will return in the same line ; if it is

thrown obliquely, it will glance off with the same degree of obliquity in the other direction. Light is reflected from plane surfaces in the same manner.

This reflection is illustrated in the figure, which represents a mirror, and a ray of light falling upon it and again reflected.

25. Apparent Place changed by Reflection. — As we always seem to see an object in the direction from which its rays enter the eye, a mirror which changes the direction of the rays will change the apparent place of the object. This is shown in Fig. 5, where the image of the candle is seen by reflection as far behind the mirror as the real candle is in front of it. The image is thus seen in the direction which the rays of light take after reflection.

26. Concave Mirrors. — By considering that rays are reflected from plane surfaces with the same degree of obliquity with which they fall upon them, we shall be

24. Explain the reflection of light ? 25. Explain the change of appar* ent place by reflection ? 26. Why do concave mirrors converge rays of light ?

LIGHT.

able to comprehend how it is that concave mirrors have the property of converging rays of light, or bringing them together in a point.

A number of small plane mirrors, situated obliquely toward each other, as represented in the figure, and as they might be arranged in a bowl or saucer, would evidently have this effect. As a concave mirror may be regarded as made up of innumerable plane mirrors, similarly arranged, it <^- would obviously be productive of the same effect.

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27. Refraction. — Refraction is the change of direction which a ray experiences in passing obliquely from a rarer into a denser medium, or the reverse.

28. The figure represents a block of glass, and shows the direction which a ray of light w r ould take on entering and emerging from it. On enter

y ing, it makes a bend, and passes on 7| through the glass less obliquely; that is, more nearly in the direction of a line drawn perpendicularly to the surface of the glass, and continued through it. On passing out again it would be bent aw T ay from such an imaginary perpendicular line, and resume its previous course.

29. Another Statement of the Law. — As the perpendicular has only an imaginary existence, it is perhaps easier to fix in the mind the changes of direction of rays passing in and out at regular surfaces thus : A ray, on entering a denser medium, pursues w T ithin it a course further from the nearest portion of the surface than its original course would be if continued. And a ray entering a rarer medium takes a course nearer the nearest portion of the surface than its original course would be if continued. These statements are true for all plane or uniformly curved surfaces.