IRLF \ A I LIBRARY OF THE UNIVERSITY OF CALIFORNIA. Class CHEMISTRY FOR YOUNG PEOPLE \> OF THE UNIVERSITY OF Reproduced from " Young's Elementary Principle* of flhfmistry," by permiKsinn of 7). Appleton A Company DlMITRI IVANOVITCII MfiNDELfiEFF B. Siberia, Ic834. CHEMISTRY FOR YOUNG PEOPLE By TUDOR JENKS AUTHOR OF "ELECTRICITY FOR YOUNG PEOPLE/' "PHOTOGRAPHY FOR YOUNG PEOPLE/' ETC. WITH SIXTEEN ILLUSTRATIONS AND TWENTY-SEVEN DIAGRAMS NEW YORK FREDERICK A. STOKES COMPANY PUBLISHERS COPYRIGHT, 1909, BY FREDERICK A. STOKES COMPANY November, 1909 ACKNOWLEDGMENTS We take this opportunity of acknowledging the courtesy of the following publishers who have helped us in connec- tion with the illustrations of this book : D. C. Heath & Company (" Descriptive Chemistry/' by Lyman C. Newell). J. B. Lippincott Company (Wurtz's " Elements of Mod- ern Chemistry"). Charles E. Merrill & Company ("Modern Chemistry/' by F. N. Peters). D. Appleton & Company (" Elementary Principles of Chemistry," by A. V. E. Young). THE PUBLISHERS. 205100 INTRODUCTION IN purpose this book, like the two preceding vol- umes of the series, which dealt respectively with electricity and photography, makes no attempt to fill the place of a text-book, either in its contents or its purposes. It is planned to give the young reader such a general account of the modern science of chemistry as will prepare him to know better what place the science holds in modern life, and how it is related to other sciences. For this reason it is much more general in its nature than a school- book can be. It contains no complete account of any one of the elements, no directions for perform- ing experiments or for laboratory work. It does, however, give an account, first, of the commoner elements and such a discussion of them as leads to a knowledge of modern ideas of what matter is, and of its laws meaning, of course, by " laws " those general ways of action which experiments have made clear. When the reader has thus gained some acquaintance with the facts upon which mod- ern chemistry is based, he is told of the broad prin- ciples governing all chemical actions, and learns vii viii INTRODUCTION something of the great philosophers and chemists from whom we have learned to make chemistry a science. After this general acquaintance is secured, the commoner elements are taken up, and the reader is told those more important facts about each which should be known, even to one who desires no ex- pert knowledge of their qualities. After obtain- ing such general knowledge of these elements, their qualities and their uses, the reader is led to enter a little more deeply into the greater principles that enable us to understand their action one upon an- other, and to become acquainted with the Periodi- cal Tables wherein the relations of all elements to one another is shown to depend upon their atomic weight. These relations include the subjects of valence, of atomic heat, and, generally, of chemical action as classified by modern chemists. To the enormous subject of organic chemistry, or the chemistry of carbon compounds, but one chapter is given; but in this are set forth such general laws and rules as enable the reader to comprehend the complexity of the subject and the methods by which chemists are able to make new compounds and to predict their qualities. INTRODUCTION ix After this general review of the subject, there follows a discussion of the history of chemistry and of its relation to human progress, which con- tains, though in brief form, the important facts enabling young readers to know the importance of the part played by modern scientific chemistry in practical life. Then follows a set of tables which give in a complete way the essential facts in relation to all elements, thus completing those tables which in the earlier part of the book are confined to the more familiar elements. It may be stated, again, that the object of the volume is to give the young reader such an interest in chemistry and such a knowledge of it as will show its relation to other branches of human knowl- edge, and will substitute in his mind definite and clear ideas of its main principles in simple form, in the place of vague and useless notions. It is be- lieved that the reader will find in these pages all of chemistry that can be readily grasped and remem- bered by any except those special students who will necessarily go to technical books for practical in- formation. Even the skilled chemist cannot perform exper- iments without constant reference to text-books, x INTRODUCTION and in all sciences to-day the student is compelled almost at once to acquire and to use a larger or smaller reference library. While technical books abound for the general reader who wishes merely an intelligent acquaintance with the main princi- ples of any science, he is often compelled to acquire this knowledge by dint of combining extracts from perhaps a dozen volumes. To such a reader this volume should prove valuable. TUDOE JENKS. CONTENTS CHAPTER PAGE I. FROM ALCHEMY TO CHEMISTRY .... 1 II. THE AIR. OXYGEN, OZONE. BURNING . 15 III. NITROGEN AND HYDROGEN 35 IV. PROPERTIES OF MATTER 51 Y. THE ELEMENTS. THE LAWS or COMBINA- TION 69 VI. COAL AND CARBON 79 VII. NATURE OF CHEMICAL COMBINATION . . 93 VIII. ABOUT COMMONER ELEMENTS .... 107 IX. THE METALLIC ELEMENTS 129 X. METALLIC ELEMENTS, CONTINUED . . . 143 XI. METALLIC ELEMENTS, CONTINUED .. . . 161 XII. SOME OTHER METALLIC ELEMENTS . . . 195 XIII. CARBON AND ITS STRANGE COMPOUNDS . 213 XIV. CHEMICAL ACTION AND ENERGY .... 227 XV. CHEMICAL LAW. THE PERIODIC SYSTEM . 245 XVI. THE STORY OF CHEMISTRY 261 INDEX 285 ILLUSTRATIONS FULL-PAGE ILLUSTRATIONS Dimitri Ivanovitch Mendel6eff Frontispiece FACING PAGE John Dalton 12 Joseph Priestley 22 Daniel Rutherford 40 Inflating Hydrogen Balloon . 48 Dinner Two and One Half Miles Underground .... 84 Sulphur Springs 116 Drilling Copper One Mile Underground 140 Loading Cars with Iron Ore in a Typical Mine .... 146 Open Pit Iron Mining 156 Stalagmite Formation of Limestone Found in Caves . . 204 Friedrich Wohler .... V 216 Sir Humphrey Davy . . ^ , 236 Joseph Louis Gay-Lussac 264 Joseph Black , 268 Claude Louis Berthollet 272 ILLUSTRATIONS IN TEXT Priestley's Pneumatic Trough 24 Wood Arranged for Burning into Charcoal 29 Nitrogen Prepared by Passing Air over Copper ... 36 Hofmann Apparatus for Electrolysis of Water .... 42 Snow Crystals 44 Condenser Arranged for the Distillation of Water . . 46 ILLUSTRATIONS FACING PAGE Fossil Found in a Coal Bed 80 Section of Coal as Seen Through a Microscope .... 82 Apparatus for Manufacturing Coal Gas ...... 83 Section of Part of Earth's Crust near Mauch Chunk, Penn., Showing Layers of Coal 86 Diamonds, 88 Artificial Diamonds (Enlarged) Prepared by Moissan . . 89 Moissan's Electric Furnace for Making Diamonds ... 90 Vertical Section of Moissan's Electric Furnace .... 91 Extracting Sulphur from Crude Ore 118 Apparatus for Purifying Sulphur 119 Blast Furnace Diagram 147 Apparatus for Rolling Steel 149 Converter 153 Magnets 154 Preparation of Ammonia 186 Apparatus for the Manufacture of Nitric Acid .... 190 Manufacture of Phosphorus 192 Apparatus for the Manufacture of Sodium by the Elec- trolysis of Sodium Hydroxide 197 Lime Kiln 204 Acetylene Flame 220 Carborundum Furnace 233 OF THE UNIVERSITY OF Chemistry for Young People CHAPTER I FROM ALCHEMY TO CHEMISTRY THERE are certain of the sciences with which we all know we are concerned daily. Some contribute so directly to our amusement, or are so universally taught, that it is impossible to grow up in entire ignorance of their principles. Even if we do not recognize that we are dealing with scientific facts, yet we learn the facts as children, and when we come to study the science to which they belong, find that many of its facts are already known to us. One of these, for example, is the science of physics. Though the name may sound strange to a young student, yet he very soon finds that he is acquainted with many of the things taught him. He has learned that bodies have weight, are elastic, have cohesion or adhesion, may be measured and compared. In botany and in zoology every child has some little training. He learns to distinguish 2 FEOM ALCHEMY TO CHEMISTRY one animal and one flower from another, and when he is taught the science that relates to them, he finds he has learned already a great number of facts to which he can apply the principles he acquires. With chemistry the case is different. It is one of the latest of the sciences. Although it is true that chemistry enters into every-day life, the changes with which it is concerned are not such as can be easily made clear. In order to comprehend them at all, it is necessary that there should be a wide acquaintance with a number of facts that are not readily understood, and indeed are not under- stood at all until certain principles have been learned. The evolutionary philosophers have taught us that children go through, in a way, the same stages that mankind went through in its gen- eral history ; and as mankind was for ages ignorant of anything that can truly be called the science of chemistry, so boys and girls do not find it necessary to understand the facts of chemistry in passing through the stages of their life that correspond to the early stages of the life of mankind. The life of children, until they are well grown, does not require them to know more than is known to the savage races. It is at a much later period that FEOM ALCHEMY TO CHEMISTRY 3 they begin to put questions to answer which re- quires them to learn such general principles as those with which chemistry deals. For many centuries mankind was satisfied with the general idea that all forms of matter were made up of different things put together, but it was only late in the history of mankind that the obser- vation of the changes in substances led to the asking of questions that could be answered only by care- ful experiment, and it was still later that it became possible to construct the apparatus that made the experiments exact. It is only within about three hundred years, that is, since the sixteenth century, that there can be said to be any science of chemis- try. Up to that time, there existed, even among the wise men, only certain general notions that had added little to men's knowledge since the days of the early Egyptians. It is difficult to give an account of these early beliefs, especially because where there was so little exact knowledge, and where each wise man, magi- cian, or priest and these three capacities were often united in one individual imagined for him- self how substances existed, were made up, or acted upon one another, there could be little agreement, 4 FEOM ALCHEMY TO CHEMISTRY and their notions cannot be reduced into simple statements. There was a general opinion that substances were to be roughly classed under four or five head- ings, that is, were made up of four or five " ele- ments." These were said to be earth, air, fire, water, and ether. Air meant to the ancients every sort of gas or gaseous substance; fire was any sort of flame or heat, and as life seems always accom- panied by heat, it came to be looked upon as the principle of life; water included all liquids, some- what as air included all gases ; earth was a general name given to all mineral substances, and, indeed, practically to all solids. Ether is more difficult to define. It seemed to include something that was more spiritual than air, and was used to explain what could not otherwise be accounted for. As the unknown region became smaller, there was less and less reference to the ether, and in later times the element, air, was used much as in earlier times ether had been. Even to Shakespeare's time we shall see that this general conception of the four elements prevailed among all save the most learned. It was impossible that even the rude observa- tions of early times should not show that now and FKOM ALCHEMY TO CHEMISTRY 5 again one of these elements seemed to be passing into another ; for a solid when exposed to fire would first change to a liquid, and then would evaporate entirely ; or, instead of evaporating, would give rise to a gas that caught fire and seemed to change to flame. Thus the very crudest experiments would show that the element " earth," or a solid, would change into the element " water," that is, a liquid, this into a gas or " air," which in turn would go back to flame. From such observations it was certain that ex- perimenters should be led to the conclusion that it was possible for one of their elements to take on the appearance, or to assume the qualities, of another. At a time when the imagination was active and was not controlled by facts (simply be- cause facts were so little known), who can blame the old philosophers for their belief that the ele- ments were capable of changing one into another, and thereby becoming convinced that it was possi- ble to convert one into another, almost at will, if only the right method could be found? From such conclusions came the beliefs of the alchemists, and in them we reach the beginnings of the science of chemistry. 6 FKOM ALCHEMY TO CHEMISTRY In this name, chemistry, we have still the old Arabic word that appears also in alchemy. Al is, of course, the word for " the," as we see it in the name, Al-Koran, or The Koran ; so alchemy simply means " the chemy." The origin of the latter part of the word is more or less obscure. So far as it has been traced, it seems to signify the extraction of the juice of plants for medical purposes, and thence to have come to mean the making of drugs, and processes akin to that. It therefore was early applied to the mingling and treating of natural sub- stances to produce changes in them. In the course of time, those who were skilled in these arts often gave their efforts to the search for the means of making, or extracting, the precious metals, silver and gold. Believing that it was possible to change one substance into another, and not knowing enough to limit the possibilities of extracting one substance from another, the search for an easy means to make gold and silver was pursued by most of those who became skilled in laboratory work. Knowing how futile were their efforts, we are likely to think of the old alchemists as engaged in a fool's quest. But before the rise of modern sci- FROM ALCHEMY TO CHEMISTRY 7 ence, there was no reason why the ancients should consider the making of gold and silver out of other cheaper substances as a dream. Indeed, a few his- torians go so far as to admit that some stories recounting the success of alchemists seem to be supported by excellent testimony. But, at all events, the alchemists who searched for means to make gold and silver, and at the same time for means to prolong human life, made experiments and observations, learned methods and principles, that have been invaluable in founding modern chem- istry. The history of these old alchemists is most fascinating, for, besides the actual practical facts of their experiments with all sorts of substances, and their studies into the laws of nature, there is a wealth of material relating to their dreams and fancies connecting the practice of alchemy with other arts and sciences, especially with astrology and astronomy. Many of the beliefs they held in regard to the connection between the heavenly bodies and earthly substances, have left traces in chemical terms and,' in words of daily use. Each of the metals was supposed to be mystically related to one of the planets. Gold, as the most beautiful and least corruptible of metals, was as- 8 FKOM ALCHEMY TO CHEMISTKY signed to the sun, the greatest object in the heavens; silver, for many reasons, was linked with the moon ; mercury named alike the planet and the metal; the red and warlike planet Mars had its counterpart in the red-rusting weapon-metal, iron ; and the qualities and virtues assigned by astrolo- gers to the planets were believed to have their coun- terparts in the properties of these metals. The whole science, or art, of the alchemists has been well called " the sickly but imaginative infancy through which modern chemistry had to pass before it attained its majority, or became a positive science." The ancient alchemists could go only a certain distance in their discoveries. They were patient, laborious, inventive, and were excellent observers. They were bold and imaginative in forming theories about their work, but they had not the power of bringing their theories to the test of proof, for they lacked the necessary apparatus to make their ex- periments exact and conclusive. This was one rea- son why chemistry came late as a grown-up member into the family of sciences. Astronomy, for exam- ple, took on the form of a science much earlier, since its facts required little else than observation FROM ALCHEMY TO CHEMISTEY 9 and the applying of reasoning to what was seen. Long after astronomy had begun to be truly scien- tific, chemistry was still undeveloped, and was ham- pered by a mass of superstitious or magical theories that had not yet been cleared away. In the sixteenth century there came about a change in the objects pursued by the alchemists. They had hitherto sought the " philosopher's stone " a magic substance that would convert baser met- als into gold ; the " universal solvent," that would dissolve all substances ; or the " elixir of life " a drink that would prolong life. But, abandoning these wild quests, they now began to believe that their arts should be devoted to finding out how to prepare medicines. The general terms used for the four elements about this time began to be replaced by more defi- nite words. The chemists, or alchemists, of that later day replaced the old words, earth, air, fire, water, by what they called the " principles," salt, silver, and mercury. These were believed to be modifications of water, which was considered the true principle of all things, and air was considered a separate, somewhat unearthly element. About this period also grew up the recognition that the 10 FKOM ALCHEMY TO CHEMISTRY liquids had two general characters, being either acid or alkaline. It was believed that the health of the body consisted in a true balance of these opposite qualities. Robert Boyle, an Englishman living between 1627 and 1691, attacked these general notions, pointed out the influence of heat in forming new bodies, and suggested that all things may consist of one universal matter, portions of which differ from one another in certain qualities. This uni- versal matter he believed to be capable of forming new bodies by a combination of its smaller particles or portions. But, acute as Boyle proved to be in pointing out the mistakes of others, it was impos- sible that he could then come much nearer to the truth than they had done. Following Boyle came a number of experimenters who put forth various theories to account for what they had noticed in their laboratory work of these we give a general account in a later chapter. It was not until the beginning of the nineteenth cen- tury that chemists were led by the researches of Dalton to what we now believe to be the right theory of the make-up of matter, the theory which put chemical work upon a true scientific basis and FROM ALCHEMY TO CHEMISTRY 11 thereby led to the rise of modern chemistry. That modern chemistry possesses all the truth, is not to be asserted ; but that it is practically true has been proved by the control which chemists have acquired over matter. They may not know all the facts in regard to how substances are formed, but at least they know enough to separate substances into their elements, and even how to make these elements join to make new and before unknown substances. Discoveries in the future may make this knowledge more accurate in detail, but it can never be entirely set aside. In other words, modern chemistry is true so far as it goes, and proves itself by its experi- ments. The old chemistry contained some truth, but there was little truth in the beliefs held by the older chemists to explain what they had observed. With Dalton, therefore, modern chemistry begins. John Dalton, born September 5, 1766, in Eng- land, was a Quaker. He taught school, lectured on natural philosophy, and became interested in tak- ing observations of the weather. For this purpose he made an instrument for finding out how much water there was in different falls of rain. But Dalton, not satisfied with measuring how much rain fell, took to asking the reasons why. He examined 12 FROM ALCHEMY TO CHEMISTRY how much water was carried in the air under differ- ent conditions. Then he was led to inquire how the vapor of water could possibly exist in the air without becoming mixed in with the gases that make up the air. This led him to reason upon the question of the mixture of gases one with, another, which led him to wondering how gases were made up; for, of course, each particle of any gas still remained itself, even when two or more gases be- came mixed together. In Dalton's time it was already . known that water consisted of the joining of two gases, hydro- gen and oxygen. So the studious Quaker youth, when he began his keen reasonings, found himself obliged to account for the fact that the vapor of water could be mixed generally throughout the air, could then be deposited from the air, as in the fall- ing of dew or rain; could evaporate, or be taken up by the air again, all without losing its identity as water. Yet it was possible by chemistry to sep- arate this substance, water, into two gases, neither of which was like that from which it was separated, the liquid water. When he had thought out this problem, Dalton Itrprudnceil from " Young' i Elementary Principles of Chemistry," by permission of I). Appleton . AiffUvton Jk Company. JOSEPH PRIESTLEY B. England, 1733. D. Pennsylvania, 1804. OXYGEN, OZONE 23 in a glass retort, or glass vessel, the oxygen rises to the upper part and may be drawn off free from the nitrogen and other gases that were mixed with it in the air. The metallic mercury forms in glob- ules, or a film, on the cooler part of the glass re- tort. It is just as well to explain here how this gas is collected from the retort. The retort may be, for example, a vessel globular in shape, with a long narrow tube projecting from the top. To the end of this tube is attached another tube of glass that goes into a pan of water. A jar is filled with water and then turned upside down, with the mouth below the surface of the water in the pan. The oxygen issuing from the end of the glass tube rises into the jar, and as it gathers, displaces the water. When enough has been collected, a flat piece of glass is slid over the mouth of the jar, which can then be lifted from the pan and remain full of oxygen. . /. This arrangement also was due to Priestley, and is called the " pneumatic trough." A similar experiment may be made with other metals than mercury. With some the oxygen has little affinity, and from these it will readily part 24 OXYGEN, OZONE when heat is applied. These, of course, are the best for experiments. Another experiment separates the oxygen in water from the hydrogen. This is done by conduct- ing electricity into a jar of water, upturned as be- fore over a pan, and providing another wire for the outgo of the current. As the current is conducted From Wurtz's "Elements of Modern Chemistry. PBIESTLEY'S PNEUMATIC THOUGH i. through the water from one pole to the other, it produces a separation of the two gases that are combined into a liquid. One of these gases gathers in bubbles at one pole, the other gas meanwhile gathering at the opposite. When enough gas is collected to form a fair-sized bubble, it will rise from the water. If, now, two small tubes have been OXYGEN, OZONE 25 put over the ends of the wires, each will receive only one kind of bubble. One, therefore, will con- tain oxygen, the other hydrogen. Neither of these methods is the one used for mak- ing oxygen commercially in large quantities, but the principle is the same in the commercial method. It consists of heating compounds of oxygen until the oxygen is given off as a gas. The compounds often used are potassium chlorate and manganese dioxide. Sometimes oxygen is got by forcing air through a tube containing a chemical that will absorb oxy- gen. From this compound the oxygen is after- wards recovered. A very recent method of obtain- ing oxygen is to condense air by cold and pressure into a liquid, when, if this liquid be allowed to evaporate, the nitrogen that was in the air escapes more rapidly than the oxygen, and the liquid left behind is almost pure oxygen. When the gas has been obtained, it will be found to have these properties: it is colorless, odorless, tasteless; it is slightly heavier than atmospheric air. When oxygen is left in contact with water, the water takes up some of the oxygen, just as if the gas were dissolved in the water. This last property is most important. Any water 26 OXYGEN, OZONE that is kept in agitation, as the ocean by its waves, or a river by its flowing, is constantly taking up oxygen from the air. The oxygen thus taken up supports the life of fishes, and also forms harmless compounds with all sorts of impurities in the water, thus making the water wholesome when drunk. Bemember that although the water itself is by weight eight-ninths oxygen, yet this oxygen is so combined with the hydrogen in the water that it is of no use to the fishes in breathing. Neither* is much of it available to combine with other sub- stances, for it is not " free." It is the free oxygen added to the water that serves the fishes in breath- ing through their gills, and also acts as a purifier. The amount of oxygen thus dissolved by water is only about one part oxygen to thirty-three of water. The most striking property of oxygen is the readiness with which it combines with almost all other elements. A few exceptions are fluorine, bro- mine, and the extremely rare gases already men- tioned. This "combination" takes place in vari- ous ways. When exposed to the air metals show certain changes that result from the action of oxy- gen upon them. In the case of iron, this change is " rusting." The metal, iron, combines with oxy- OXYGEN, OZONE 27 gen to make an " oxide of iron," which is only the scientific name for rust. Lead, zinc, and copper, show a similar change to a less degree. A rust is formed on their surface, but since this rust is slight, and is noticed mainly by their becoming dull, we usually speak of these metals as being tarnished by air. Phosphorus combines with oxygen very readily at ordinary temperatures. An instance of this property is the lighting of a sulphur match. The match consists of phosphorus and sulphur covered with a little paint. Scratching a match removes the paint, and slightly warms and compresses the chemicals, the oxygen of the air unites with the phosphorus, and the heat thereby produced sets fire to the sulphur, which in turn inflames the stick. The heat and light caused by the action of oxy- gen is what gives the brightness and warmth gained in burning fuel. If a charred stick with the small- est spark upon it be thrust into a jar of oxygen, it burns fiercely. Even an iron wire, when heated to redness and thrust into oxygen, burns as if it were wood, throwing off sparks as it is consumed. Except for the nitrogen in the air, the slightest spark would result in a most terrific and wide- 28 OXYGEN, OZONE spread burning of all sorts of substances within reach. The quick combining with oxygen, which we call burning, is not really different, except, in rapidity, from processes that we know by other names. The decay of wood and other substances, and the rusting of metals, are just as truly a burn- ing, or oxidizing, as the actual flaming of a lighted match. After the process of combining with oxy- gen is finished, it is found that there is a change in the substances exposed to it, and the compounds produced by this oxidizing or taking up of oxygen are called, in chemistry, oxides. If these com- pounds are heavier than air, they are left as a result of combustion ; if lighter than air, they rise, and are carried off, unless confined. Thus in an ordinary fire of coal and wood, the carbon (the element of which they largely consist and which is seen nearly pure in unconsumed charcoal) will, if plenty of oxygen is supplied to the fire, form a gas known as "carbon dioxide." The prefix di, is simply a Greek word for " two," or " double." The carbon dioxide, being lighter than air, is carried off. If a fire is burned without sufficient air to provide plenty of oxygen for its combustion, only a part of the carbon goes off in gas, and the rest remains in OXYGEN, OZONE 29 charcoal, or pure carbon. In the old folk-lore stories boys and girls will remember how often "charcoal burners" are spoken of. These people made their living by piling up wood into great heaps, covering it closely with clay, turf, or similar material, and then setting fire to it, but shutting off almost all the air. This was a method of sepa- rating from the carbon only such substances as would be easily consumed, and thus leaving the car- SECTION SHOWING WOOD ARRANGED FOR BURNING INTO CHARCOAL bon, or charcoal, ready to be used again as fuel. The value of the charcoal as fuel in old times con- sisted in the fact that it made a clear, bright fire, burning slowly, and without much smoke an ex- cellent cooking-fire, before coal was known. It has already been said that the oxygen drawn into the body by the lungs is used somewhat in the same way as when it is admitted to a fire. It unites at first with the red corpuscles in the blood, and by 30 OXYGEN, OZONE these is carried throughout the whole body. It burns up the waste products of the whole system, thereby creating warmth and also getting rid of useless material. One product of this combining in the body is the same " carbon dioxide " that we find in fire smoke; and as that is allowed to escape through the chimney, so the carbon dioxide is brought back to the lungs and breathed out again into the air. Thus we inhale air rich in oxygen and exhale air deprived of much oxygen and rich in carbon dioxide. Kapid breathing increases the speed of these processes, but if carried beyond what is reasonable, produces a condition like that of fever. Indeed, fever seen in disease is only a condition wherein nature is trying to oxidize and get rid of an excess of waste material. Although we have said that most cases of com- bustion mean oxidizing, it must not be thought that wherever heat and light are produced, oxygen is at work. The same effects may be produced by the action of other chemicals. Thus, for ex- ample, the gas chlorine combines so actively with hydrogen gas that there is a true " burning," which sometimes takes place so quickly as to be like an explosion. Sodium " burns " in chlorine, and phos- OXYGEN, OZONE 31 phorus also; nor are these the only examples of the sort. Ordinarily, however, it is true that ox- idizing is what we mean by burning. OZONE There is also, besides the ordinary form of oxygen, another form, in which the oxygen is, as it were, condensed. It is believed by chemists that this form comes about by a different arrangement of the particles of the gas by which they are able to be brought nearer together. This second form is known as ozone, a name derived from the fact that it has a striking odor, ozo being derived from the Greek verb " to smell." As you might guess from the name, while ordinary oxygen has no odor, there is a sharp and characteristic odor to the ozone. The idea of chemists is that in ozone three of the smallest possible portions of oxygen are grouped closely together, whereas in the ordinary form, only two of them are grouped. They are led to this conclusion for the reason that when oxygen is changed to ozone, it loses bulk and becomes only two-thirds as great in volume. In this way a hun- dred parts of ozone can be changed, or expanded, into a hundred and fifty parts of oxygen. This 32 OXYGEN, OZONE expansion is brought about by heating the ozone to a high temperature. To change it to ozone again, it is treated by what is known as the silent dis- charge of electricity a discharge from a multitude of points. While oxygen has no color, a tube filled with ozone and looked at against a white light shows a slightly bluish tinge. All these matters will be better understood after the reader has gone over the fourth chapter of this book. Both oxygen and ozone can be condensed to a liquid form by intense cold. In order to bring this about, ozone must be cooled to a temperature of more than a hundred degrees below zero Centi- grade. Oxygen, to be reduced to a liquid, must be cooled to more than 118 Centigrade, and com- pressed under an enormous pressure. Ozone weighs more than oxygen, being quite a little heavier than air, while oxygen is only slightly heavier. There is another difference between the two forms of the gas. While oxygen is not easily changed from its usual condition, ozone is what is known as un- stable, that is, it tends to change back into oxygen under ordinary conditions. There are other reasons for knowing ozone to be condensed oxygen besides those given. While oxygen is an active gas, ozone, as we would ex- OXYGEN, OZONE 33 pect, is even more active in oxidizing other sub- stances. This, form of oxygen was first discovered by pass- ing electricity through a tube of oxygen. Ozone is now known to be produced in the air during a thunderstorm. The odor suggests that of burn- ing sulphur. As already said, its action is like that of oxygen, but more active in tarnishing metal, bleaching (by changing the composition of coloring matter) and corroding many softer substances. It has a use as a disinfectant. The air contains cqn- stantly a very slight trace of ozone, wjiich one au- thority states is one part in 7.00,-ObO. It is most abundant on t&e seashore and in the open country far from cities. A recent theory ascribes the for- mation of ozone in the air to the action of the " ultra-violet " rays of the sun upon the oxygen in the higher and exceedingly rare portions of the atmosphere. These rays are those most active in affecting the photographic plate. We shall find, in considering other elements, that a number of them are like oxygen in appearing in more than one form. But that these forms are nothing besides the original element can always be shown by changing one form of the element back into another without trace of any other substance. CHAPTER III f NITROGEN AND HYDROGEN NITROGEN makes up four-fifths of the atmosphere in bulk. Its name was derived from the fact that it was found in saltpetre, another name for which is nitre. The gas, before it was known to be an important part of saltpetre, went by the name " azote," a word derived from the Greek and mean- ing that it was a gas which would not support life. This term is still used in some foreign countries, and also occurs in the adjective " azotized." In the air the nitrogen and oxygen are not com- bined chemically, but are merely mixed together. As there is so much free oxygen in the air, nitrogen can be readily obtained by any means that will separate oxygen from it. One way of doing this is to pass a current of air through a tube contain- ing red-hot copper filings or shavings, these being used because they give so much surface. When hot, the copper combines readily with the oxygen, making a copper oxide. Since the nitrogen does 35 36 NITROGEN AND HYDROGEN not so -combine, it passes through the tube free from oxygen, and so cannot be collected in a suit- able vessel. When thus obtained, nitrogen is found to be a colorless, tasteless, odorless gas, as is oxygen, and slightly lighter than air. It will neither burn nor will it support combustion that is, a burn- ing substance thrown into nitrogen will, for lack NITBOGEN, PBEPAEED BY PASSING AIR OVER COPPER of oxygen, soon be extinguished. If breathed by animals, nitrogen will cause death, not because it is a poison, but because the lungs being filled with it are deprived of oxygen. Its principal use in nature, from our point of view, is its value in protecting us from the injury that would be done if the air were oxygen unmixed with this harmless gas. The reasons why chemists assert that air, though NITROGEN AND HYDROGEN 37 made up of a mixture of nitrogen and oxygen, is yet not a compound of these gases, are these: If the two gases are mixed in the same proportions as those contained in air, we see none of the usual effects that come from chemical action. There is no heat, no change in bulk, and the mixture be- comes like any ordinary air. Secondly, as will be seen later, when chemical compounds are made, the quantities of the various combining elements are always in fixed proportions, and the elements never combine except in fixed amounts. In the air, the proportion of nitrogen to oxygen is not that in which they thus combine. Third, in chemical com- pounds the proportions are always the same in the same compound, but in air the proportion of nitro- > . \ * M gen to oxygen is not always the same. Fourtji, and most convincing, air when shaken up with a quan- tity of water in a closed vessel, loses some of its bulk; then, if the water containing this dissolved air be put into another vessel, and be heated, it will expel this air, and the air will be found to be a mixture of nitrogen and oxygen in new propor- tions. Instead of containing four times as much nitrogen as oxygen, it will contain nearly twice as much oxygen as nitrogen. This would seem to 38 NITROGEN AND HYDROGEN show that the water has dissolved much of the oxygen and very little of the nitrogen. But if the air had been a chemical compound, the propor- tions of the two gases, when the air was recovered from the water, would not have changed. If it be argued that the excess of oxygen may have come from the water, the answer is that in that case the water would have changed its com- position, which is not the case. Besides its forming so large a portion of the air, the gas Occurs very commonly in the form of ammonia, a compound containing one atom of nitrogen to three of hydrogen. Another form in which nitrogen is found most useful is in nitric acid. Nitrogen may readily be prepared by cover- ing burning phosphorus that is floated in a large vessel of water. The burning of the phosphorus is a combining of oxygen with" it, and this oxygen being taken from the air in the jar, leaves nitrogen, more or less pure. Nitrogen, as has been indicated in showing the proofs that air is a mixture, is not easily soluble in water. It requires a hundred parts of water to dissolve, or take up, about one and a half parts of nitrogen. Although the nitrogen in the air is NITROGEN AND HYDROGEN 39 not taken up by the system when the air is breathed, yet animal substances all contain nitrogen, a proof that they procure this gas indirectly. Most animal- foods contain compounds of nitrogen, and it is from this source that the nitrogen in the system comes. As animals procure their nitrogen com- pounds from food, so plants obtain nitrogen com- pounds from the soil, and if the soil be exhausted of its nitrogen, in order to make it productive it must be fertilized by the addition of nitrogen in some form. Not long ago it was discovered that certain plants, such as peas, beans, and clover, are able to take nitrogen directly from the air by the aid of bacteria, minute forms of life, found upon their roots. These bacteria provide nitrogen so freely that their roots serve to enrich the soil, and thus take the place of artificial fertilizer that is, an exhausted soil can be renewed in its nitrogen by growing a crop of peas, beans or clover, upon it. Afterwards, plants that need the nitrogen com- pounds will find them in the soil so enriched. Nitrogen was discovered in 1772 by Rutherford, a Scottish physician, who found that it would ex- tinguish a candle, and suffocate small animals con- fined within it. Then the great French chemist, 40 NITKOGEN AND HYDKOGEN Lavoisier, showed what part it played in common air, and he it was who gave the name " azote." In the branch of chemistry known as " organic," nitrogen plays a most important part, and besides its universal presence in animal flesh, gives rise to compounds of very marked properties such as the albumens, the aniline dyes, the explosives, nitro- glycerine and gun-cotton. In inorganic chemistry it gives us nitric acid, ammonia, and "ammo- nium " which will be explained. Having thus a slight acquaintance with the air and the gases of which it is a mixture, let us now take up some study of a chemical compound the most familiar one and that Dalton studied. As soon as we begin to examine the character of the substance, water, we find that we are dealing with something that is to be sharply distinguished in certain qualities from that mixture of gases known as air. Yet water, too, may likewise be separated into two gases. But precisely in the way it was proved that air is only a mixture, and not a compound (of oxygen and nitrogen), so it maybe shown that water is not a mixture of two gases (hydrogen and oxygen), but is a true chemical compound of them. Young's Elementary Principle* of Chemistru," by permisxinii of I). Applet .{ (Jumpany, DANIEL RUTHERFORD B. Edinburgh, 1749. D. 1819. NITROGEN AND HYDEOGEN 41 Yet water was considered, only a little over a hundred years ago, to be an element and not separa- ble into anything simpler. The discovery of the true nature of water came about toward the end of the eighteenth century, and there were a number of steps before the nature of this compound was understood. Thus Priestley, the discoverer of oxy- gen, noticed that when a mixture of oxygen and hydrogen gases was exploded, there was a deposit of drops of water upon the cool sides of the tube. About a year later, another chemist, Cavendish, showed that when two parts of hydrogen and one part of oxygen were mixed and exploded, nothing was left in the vessel where the explosion took place, except water. Two years later, Lavoisier, after going over the previous experiments of others, clearly recognized and explained just how the two gases, and they alone, when combined formed the compound, water. When this had been declared, other chemists proved and verified the statement. This they did by put- ting together carefully measured volumes of the gases, causing them to unite so as to form a meas- ured quantity of water, and also by taking apart a quantity of water and securing from it the same 42 NITROGEN AND HYDROGEN proportions of hydrogen and of oxygen. Thus early in the nineteenth century it was finally proved that water was a chemical compound and always con- tained precisely two parts by volume of hydrogen, and one of oxygen. By weight there were eight units of oxygen to one of hydrogen. It is easy, nowadays, to ver- ify these results. If the gases be mixed in a tubk, the passing of an electric spark through the mixed gases causes them to combine, forming pure water. And, on the other hand, as has been noted, the electric current in passing through water will separate its gases and collect them at opposite poles. HOFMANN APPARATUS The t wMdl water j FOB ELECTROLYSIS OF WATEB. in chemical actions is almost universal. It serves as a means by which the elements can reach one another and act upon one another. The combination of ele- ments is for the most part brought about only in NITKOGEN AND HYDKOGEN 43 two ways, either by heat (or flame) or by moisture. When perfectly dry, most elements may be brought into contact without affecting one an- other in the slightest degree ; but by " perfectly dry " is meant a dryness which can only be brought about by careful manipulation; and by " contact " is not meant a rubbing together with pressure for this produces heat, and also may promote combination in other ways. Ordinarily there is in the atmosphere and in all substances more or less water or watery vapor. We do not need to be told that the amount of this vapor, or water, varies very greatly, not only from time to time, but in different parts of the earth. We have every degree of moisture, from the parched and burning air of deserts, to the more than complete saturation of the air which results in the heaviest downpours of rain. It has been calculated that the average amount of water in a thousand parts of air may be put at about four- teen parts. Besides the enormous quantities thus held in the air, we know from our earliest studies in geography that three-fourths of the whole sur- face of the globe are covered with water. Even those substances which we ordinarily consider dry 44 NITROGEN AND HYDROGEN consist often for the most part of water. Every vegetable growth, the animals, even the rocks them- selves, are filled with this liquid. The human body is about seven-tenths water, and most foods consist of very large percentages of water, from more than nine-tenths downward. We must not forget, when summing up all the amounts of water on the globe, From Wurts's " Elements of Modern Chemistry" SNOW CEYSTALS the enormous ice-caps at the poles, the ice cover- ings of mountains, and their snowy summits. Thus the whole world may be looked upon as permeated and soaked in this combination of these gases, hydrogen and oxygen, and the liquid they form plays a multitude of useful parts in all the processes of nature. It will dissolve nearly all substances, and with them in solution flows freely from place to place, carrying them with it. It is constantly being taken up into the air, and as continually sent back again to the world beneath. NITROGEN AND HYDROGEN 45 As it moves about on the surface of the earth it acts both chemically and physically. Chemically, it changes the substances with which it is in con- tact, taking away some elements and adding others. Physically, it changes the shapes and places of sub- stances and their compounds, thus carving out the surface of the earth or in other places building it up, decomposes or forms rocks, and is, as it were, the life-blood of the world, causing in its surface and in its constitution changes similar to those that the blood brings about in animals. Water also affects the substances with which it comes into contact by absorbing or giving out heat, thus changing their temperature. In its own trans- formation from solid to liquid, from liquid to vapor, and back again to liquid and solid, it not only af- fects the temperature of everything near it, but also takes up or parts with contained chemical elements, thus working other changes. By means of water, both plants and animals are enabled to take up and make use of the elements and com- pounds that are dissolved in it or carried along in \ - '- its substance, and as will be seen later this " dis- solving " is a process that is far from a simple one. It is nearly impossible to conceive what our 46 NITROGEN AND HYDROGEN world would become without water, and by this it is not meant that we should imagine the world deprived of the two gases of which it is composed, but only of their combination as water in its ordi- nary liquid or vapor form. Most substances, when CONDENSEB ASBANGED FOE THE DISTILLATION OF WATEE The condenser consists of an outer tube, AA, provided with an inlet and an outlet for a current of cold water, which sur- rounds the inner tube, BB. The vapor from the water boiling in the flask, C, condenses in the inner tube, owing to the de- crease in temperature, and drops off from the lower end of this as the distillate, into the receiver, D, while the impurities re- main behind in the flask. deprived of water, would crumble away into a pow- der. There could be neither animal nor vegetable life. A number of chemical changes upon which not only life, but the existence of numberless com- pounds depend, would altogether cease. Even where much of the water has disappeared from a NITROGEN AND HYDROGEN 47 heavenly body, as in the case of the moon, the result is to make it a dead and apparently useless body floating in space. It is unnecessary to say to any thoughtful reader that the taking away of water from the substances at man's command, even if he could live without it, would stop nearly every species of human labor beginning with all agriculture. HYDROGEN Of oxygen we have already told the few most im- portant facts. But hydrogen, the other constituent of water, is even more interesting, as will be seen before even this elementary book is finished. There is indeed a theory that all things may be variations of this one element hydrogen. Of all substances, the element hydrogen is the lightest. Air is about fourteen and a half times as heavy as hydrogen; oxygen is sixteen times as heavy, and water eleven thousand times as heavy for the same volume. In our atmosphere, a mass of hydrogen floats rapidly upward, as a cork rises in water; therefore in pouring it from one vessel to another, it must be poured upward instead of downward. 48 NITKOGEN AND HYDEOGEN A very ready method of showing the lightness of hydrogen as compared with air, is to use this gas for inflating a small balloon, or even for blowing soap-bubbles by means of a clay pipe thrust into a rubber tube connected with a reservoir of hydro- gen. The balloon, or bubble, rises in the air with great rapidity. Hydrogen was formerly used for inflating balloons, but other gases, such as illumi- nating gas, are now found to be cheaper and better for the purpose. When chemists decided, long ago, to arrange ele- ments in tables with a statement of their relative weights, hydrogen was selected as the substance by which to measure the weight of all other ele- ments. Just as in measuring lengths the metre or the foot is taken as the unit of measurement, so the weight of hydrogen is called the unit. The smallest possible amount of any element is called an " atom," and this word has long been used to describe a part of it so small that it could be separated further. Consequently, a single atom of hydrogen is taken to weigh " one unit of weight." Then by measuring the weight of any other element, or substance, or finding the number of times it will contain this weight, we may get a number that will express its i" I I s < * r NITKOGEN AND HYDKOGEN 49 weight as compared with hydrogen. In each case the amount considered is one atom. Since oxygen, for example, weighs sixteen times as much as hy- drogen, when equal volumes of the two gases at the same temperature and pressure are compared, we may say that the atom weight, or atomic weight, of oxygen is sixteen, that of hydrogen being one. A little thought will show the reader that this is as near as we can get to stating the weight of any- thing. We must always compare a substance with some standard and state that it is heavier or lighter, and so much heavier or so much lighter, than the chosen standard. There is no other way of telling what weight is. From this it follows that there is no answer to the question, What does the " 1 unit " mean when taken as the weight of a hydrogen atom? We can only say that it means the weight of an atom of hydrogen or if the weight of any other atom be taken as standard, then the weight of that atom. If we take a given quantity of hydrogen, we can tell you what weight of any substance it is equal to, and we may state this in pounds, ounces, grains, or in the metric system as litres, decilitres, grammes, milligrammes, and so on. But in chemis- 50 NITROGEN AND HYDROGEN try the weight of an atom of hydrogen was until recently always the standard. Latterly it has been proposed to take an atom of oxygen as the standard of weight, simply because this gives for other sub- stances numbers easier to handle. When we consider the make-up of various sub- stances and find that the innumerable compounds in nature or in the laboratory can be simplified, analyzed, or taken apart, into a few elements, we are led to ask whether as we learn more about chemistry and become more skilful in reducing substances to their simplest form, we shall not at last be able to show that all things are different forms of a very few substances or elements, much fewer than the eighty now considered to be simple, uncompounded elements. We may in imagination go even further and ask whether we shall not come to a time when we shall know all substances to be only various forms of a single element. Many think, as already stated, that if this time should ever come, this single element will be hydrogen. CHAPTEE IV PROPERTIES OF MATTER THE first requisite in studying any substance is to get it into its simplest form. Matter is defined in books upon physics as being anything that can occupy space. Physics also teaches that all mat- ter is divisible, or separable, into portions. But, for all that we can say, the defining of matter is impossible, except by telling what it does. Perhaps the easiest form of words in which we can put the thought is that which defines matter as being "anything that resists force." A little careful thought will show that we can know matter only where it resists some action of a force, as by being felt, seen, or otherwise known by the senses, by changing the action or direction of a force, as inter- rupting light or sound, and so on. So far as we know matter, it is constantly di- visible, and we have given names to these different degrees of division. If we take a substance and crush it to the finest powder, the properties of each 52 PROPERTIES OF MATTER particle remain unchanged. We may make these particles still finer by dissolving them in a liquid, or often we may melt them, or by heat convert them into a vapor or gas. Take for an illustration the substance, water, which we have learned consists of hydrogen and oxygen. We may cause it to disappear by apply- ing gentle heat, thus changing it to an invisible vapor; or, by a greater heat, we may convert it into steam, or by cold we may turn it into solid ice, and that ice may be melted again into water. Yet we know by experiment that the tiniest par- ticles of water may be brought back, unchanged, into a liquid form. We know also, from chemical experiment, that the most minute of these divisions of water must contain two elements, hydrogen and oxygen. For these different divisions of a substance chem- ists have made names whereby to follow substances in thought, even where they cannot be traced by the senses. These names are as follows : To the smallest pos- sible portions of a substance that still remain un- divided into elements, and consequently unchanged in its properties, the name molecule has been given. PROPEKTIES OF MATTER 53 This word means, in Latin, " little body." For the still smaller portions that make up such a mole- cule, that is, in the case of water, for the tiniest portions of the two gases that go together to form the water molecule, the name atom has been made. Thus we say that the molecule of water contains atoms of hydrogen and oxygen. When we succeed in obtaining the smallest possible portion, or mole- cule, of a chemical element, or non-compound body, there is reason to believe that this too is made up of atoms, even though each of these atoms be the same element as the molecule. We must remember, therefore, that all matter is considered to be divisible, first into molecules, and then into the atoms that go to make the molecule. This also implies that some molecules are made up of atoms that differ from it and from one another, while other molecules are made up of atoms that possess the same properties as the molecule. The reason why chemists have come to think of matter in this way is because it explains to them and makes clear to our minds the different forms in which matter exists, and also explains how sub- stances are made up chemically. The ordinary forms of matter known to all of us have already 54 PKOPEKTIES OF MATTER been mentioned in speaking of water, as solid, liquid, and vapor ice, water, and steam. Nearly everything appears to us either as solid, liquid, or gas, and since we have seen that many common substances are very easily changed from one of these forms to another, we have come to believe that these result only from a change of condition. Again, water is the most familiar illustration. We know that it is only a question of how much heat exists in water, whether we shall see it in the form of ice, or being converted to its melted form, as a liquid ; and by still further heat we know it to be changed to a vapor. But to explain these three states of matter it is believed that the strength of attraction holding the molecules together is what governs the state of the substance. When the molecules cling closely to- gether and are not easily separated, the substance is a solid. When this force is much weakened so that the molecules, though somewhat held together, yet may be readily movable, the substance takes the liquid form. The force being still further weak- ened, the substance presents itself as a gas ; and in this state either holds together with only the slight- est union, or even tends to separate in all direc- PROPEKTIES OF MATTER 55 tions. The study of these conditions belongs not strictly to chemistry, but to physics. But a knowl- edge of them must be attained in order that we may follow the theories upon which chemists work. When we come to dealing with the changes that affect the relations of the smaller portions, that is, of the atoms, we leave the science of physics and enter upon that of chemistry. Chemistry has to do mainly with those changes in which the molecules are separated into atoms. Remember that we have said the molecule is the smallest possible portion of a substance that can retain its properties. If, now, this smallest por- tion be further broken up into atoms, we shall know it by a change in the properties of the substance treated. When we shall have reached the state in which we deal with atoms, chemistry will show the laws by which these atoms go together again to make new compounds. By means of chemistry, then, we are able to do two things : First, to take apart the molecules of substances, and second, to put together the atoms which have been in these molecules so as to make molecules of new substances. The laws of the action of atoms in separating and combining, 56 PKOPERTIES OF MATTER and the methods by which they may be taken apart and put together, and also the nature of their arrangement, and the force that causes them to remain together or to be separated these are the field of chemistry. There are in every science two great divisions. These are known as the " theory " and the " prac- tice " ( or, as they are sometimes called, the science and the art). The theory of any science is that part of it which forms the answer in any case to the question " Why? " The practice in the same way answers to the question "How? " If we find, for example, that by putting a fire under a vessel of water, the water gradually begins to boil, as we say, " boils away," we have learned something that re- lates to practice. We have learned how to change water into vapor. It is not necessary that we should know why the result is brought about, so long as we are satisfied with the result alone. But as soon as we begin to wish to bring about any result in the best possible way, we must inquire why a certain course of action causes the result; and in the case of the water, we ask why heat should make water boil and then disappear. The answer to the question " How? " is usually a sim- PROPERTIES OF MATTER 57 pie one. It can be found out by experiment. Once having found out, we may usually repeat the work as often as we choose. But the question " Why? " lies deeper, and sometimes cannot be an- swered at all. The answer to it is in all cases merely a guess an attempt to explain more or less fully and satisfactorily. If we find that our ex- planation or theory makes it possible to foretell what will happen in new cases, then we may safely trust it and believe in it. This whole matter of molecules and atoms is one of theory. None of our senses can enable us to know directly either molecules or atoms. We can only imagine that they exist, and then give rea- sons why their existence makes clear to us the action of elements or of compounds one upon the other. It would be a long, dry, and difficult task to set out all the reasons why this belief in molecules and atoms known as the atomic theory has been accepted by nearly all men of science. It is not even yet complete or fully understood, but the be- lief in and knowledge of its laws have made it pos- sible to do so many wonderful things that those who doubt it are few indeed. 58 PROPERTIES OF MATTER This theory serves not only to explain many otherwise mysterious facts in chemistry, but also in physics, in medicine, in botany in the whole circle of the sciences. It makes us see a reason for the rules and laws by which light, sound, electricity, and heat, act and may be controlled. It is desira- ble, therefore, to get into our minds a clear notion of matter, that is, of all substances, as explained by the atomic theory. Many great philosophers have told us good ways of picturing the nature of the theory to our minds. They ask us to suppose that a single drop of water could be enlarged until it were as big as our earth; then, it is believed, the molecule might be perhaps somewhere near the size of a tennis-ball. And these molecules themselves would be made up of still smaller atoms. This is not mere guesswork, but is based on careful figur- ing by Sir William Thomson (Lord Kelvin), who knew more of such matters than almost anybody. Until very recently it was believed that the atom was indivisible and represented the very smallest portions of matter with which science had to deal. But especially after the discovery of the X-rays by Professor Roentgen, careful study of their action convinced the scientific men that the ray was made PROPERTIES OF MATTER 59 up of a stream of moving particles of matter, much smaller even than the atoms. This came to be be- lieved because of their going directly through so many kinds of matter. They would penetrate even sheets of metal. Then experiments were made to find out what these inconceivably minute particles weighed, and experiments led to the conclusion that they weighed but one-thousandth as much as a single atom of hydrogen. It is, of course, not to be expected that in a book of this sort these complicated experiments can be fully explained. We will say only that the measur- ing and weighing of the velocity and the mass of these particles was done by causing them to move aside from their regular lines of motion by means of a magnet. Then it was calculated what their velocity and weight must be in order to be bent a certain amount from their paths by the knpwn at- traction of the magnet. So, to-day, we have come to believe that from the atom itself can be separated something still smaller. Sir Oliver Lodge, another great English philoso- pher, has told us something of what these minutest forms of matter are thought to be. The name given to them is " electrons." If we imagine an atom 60 PROPERTIES OF MATTER enlarged to the same enormous degree as we have already imagined the enlarging of a molecule, then, Sir Oliver Lodge tells us, it would be found to consist of a few electrons that is, few in propor- tion to the space they would then fill flying about in orbits much as the planets move about the sun. Supposing that the atom had been enlarged until it were as big as a great house, then the size of each electron might be compared to that of a printed period, or the smallest dot that you could make with a sharp pencil-point. If the atoms in a single drop of water are so tiny that enlarging a drop of water to the size of this earth might make each atom no larger than a ten- nis-ball ; and then if we could imagine each of these tennis-balls magnified until it were as big as a church, in which case the electrons it contained would be no more than the tiniest dat you may imagine fo* yourself the inconceivable smallness of these electrons, hundreds of which are found in every atom. The pencil dot you made to represent an electron must in reality contain millions of electrons, yet you must not think of these as packed closely together. They are, in proportion to their including space, as far apart as the planets in the PKOPERTIES OF MATTEK 61 solar system. They are in motion with unimagin- able rapidity. Exactly in what paths they move we cannot tell. They seem to be repelling one another and attempt- ing to get as far apart as possible. It is believed that they are kept together, that is, kept from flying outside the limits of an atom, by electricity. It is believed, for reasons too long to give here, that all the electrons are negatively electrified. Now, like electricities repel, and so electrons repel one an- other. But it is believed that within each atom there is something positively electrified, which, therefore, attracts the negative electrons and keeps them revolving about it, just as the sun attracts the planets and keeps them from flying off into space. Whether the electric forces of which we are talking are connected with some portion of matter, or whether they consist of nothing except the motion of the ether, is not yet known. To understand what is meant by motions of the ether, let us suppose a great body of water in which there are numberless and tiny whirlpools moving with enormous force. You know that the water coming from the hose of a fire-engine or of a mining hose travels so fast that it cannot be penetrated. 62 PROPERTIES OF MATTER If you try to strike a stick through one of these streams, the stick will rebound as if it had hit metal. If you imagine the currents of the little whirlpools travelling with something like that ra- pidity, you will see that you could not push some- thing into them. They would indeed resist as if they were solid. Now, it is believed that the elec- trons are in swiftest motion within each atom of a substance, and that they resist the attempt of any- thing to come between them, just as a stream of water resists the entrance of a stick. Sir Oliver Lodge, in speaking of the atom of hydrogen, the lightest of all, supposes that it may contain per- haps seven hundred electrons, half negative, half positive. If this number may be accepted, then an atom of oxygen, which is sixteen times heavier, might be thought of as containing eleven or twelve thousand electrons, and so on with the other ele- ments, each containing as many electrons as its weight would indicate when compared with the weight of hydrogen. He also warns us that though science has de- tected these negative electrons in certain rays, the positive " electron " is only imagined, having never been detected separate from some atom. This same PROPERTIES OF MATTER 63 theory carried out would lead us to believe in the possibility that all elements are made up of the same kind of electrons, differing only in their num- ber, and possibly in their kind of motion. Remember that all this is only a belief; but it is a belief that helps us to understand and ex- plain by the laws of electricity alone many of the actions of elements on one another, chemically, that would otherwise be very complex and mysterious. Thus it is believed that all light comes from the setting free of negative electrons. They pass out from their atoms and shoot through space. When they are released from atoms with slower speed, they become evident to us as heat. When released in another way, they are known as electric action. By the same theory the escape of electrons and their striking against other substances is ex- plained what is known as radio-activity, or the emis- sion of different forms of rays, as from radium and other substances. To show how recent these views are, it was only in 1903 that scientific men decided radio-activity was likely to consist in the flinging away of atoms positively electrified. These atoms have been weighed and seem to be somewhat near the weight 64 PROPERTIES OF MATTER of an atom of hydrogen, and they are accompanied by the negative electrons, only % oo as large. One need not try to follow too closely the com- plicated thinking of the philosophers on these sub- jects. It is enough that we bear it in mind that all matter is believed to be made up, first, of molecules representing its own smallest portions; that these molecules are made up of atoms closely held to- gether, and that the atoms themselves are made up of electrons moving in orbits with inconceivable rapidity round about some central portion. Such is the latest view of the make-up of all substances, and to it we must now and again refer in order to explain chemical laws. In talking of the three forms of matter we have explained how, as heat is applied, a solid is changed to liquid, and the liquid to a vapor or gas. But what we have been explaining in regard to the make-up of molecules and atoms prepares us to understand what is meant by philosophers and chemists who nowadays talk of the " fourth state " of matter. In a gas the molecules tend to sepa- rate from one another. If this separation be car- ried still further, so that the molecules themselves, or even the atoms of a single element, are broken PROPERTIES OF MATTER 65 up into the electrons, then we shall have a new, or a fourth, state of matter, with laws of its own differ- ing from those of the other three. Concerning this fourth state, we know as yet less than of the other three, and it is at this time being most busily studied in many laboratories. It is especially interesting because to this state of matter belong the various new kinds of light rays whose action is so wonderful and was until the last few years so unaccountable. As a result of this whole method of thinking of matter under the atomic theory, we must regard the world, and the universe itself, as being made up of almost unim- aginably tiny portions, each of which is eternally in motion of inconceivable rapidity. Thus it will be seen that the old idea of " dead matter " has been entirely abandoned. Everything is in motion, and science is little more than the study of these movements. We may also, as a result of these theories, under- stand why it is that some scientific men believe that all the other elements may be nothing more than different forms of hydrogen; and for this reason. Hydrogen is the lightest of all matter. If we are trying to find that of which all other matter is made 66 PEOPERTIES OF MATTER up taking it for granted that there is one such universal element then it is hard to escape the conclusion that this one element must be that of which the atom is the lightest of all things; for surely this atom cannot be made up of larger atoms if each one of them is heavier than itself. To repeat the argument: Admitting all things have weight, if any one thing be simple and all the rest compound, every conceivable compound must be heavier than the one simple thing, since whatever is added to that simplest and lightest substance must make it heavier. If this reasoning be just, then it would seem hydrogen is that element which is the foundation of all the others. In the same way it may be argued that since elec- trons are lighter than the hydrogen atom, they may be either the simplest form of matter, or something different from matter. Then at a certain point, as matter is being separated, it ceases to be matter when it is separated into electrons. Of course, to say that electrons are not matter is to consider them only as forms of motion in the ether. We have already said that while the science of physics deals with molecules, or with substances whose properties do not change enough to change PKOPERTIES OF MATTER 67 their identity, chemistry deals with atoms, and studies substances having regard to the atoms of which they are made up, and the changes in sub- stances that are made by changing the atoms that compose them. It must be remembered, however, that even in chemistry we deal ordinarily with sub- stances in molecules, since the changes brought about by separating and combining atoms are not possible to observe. The atoms do not remain in a free state. No sooner are they set free from one combination than they enter into another. OF THE UNIVERSITY OF CHAPTER V THE ELEMENTS. THE LAWS OF COMBINATION IN order that record may be kept of these changes of atoms, and also that they may be understood and followed, there is a system of notation and of nam- ing. The chemical elements have each assigned to them a simple symbol. Ordinarily the symbol of an element is the first letter of its name, but where this would make confusion, other letters may be added. Some of the older elements are still called by their Latin names, and the initial is taken from the Latin word. Each of these symbols stands not only for the element, but for one atom of that ele- ment. If we wish to express more than one atom, a number is put before the symbol. To take as illustrations elements of which we have already learned something, oxygen has the symbol O, which means one atom of oxygen. For nitrogen in the same way we have the symbol N, and for hydrogen the symbol H, the letter standing in each case for a single atom. If we wish to ex- 70 THE ELEMENTS press more than a single atom, we put a number before it. Thus 4 O would stand for four atoms of oxygen. When the atoms are in a compound, the figures expressing their number is written after the symbol and may be made smaller and either higher up or lower down. Thus the well-known symbol for water is H 2 O or H 2 O, meaning two atoms of hydrogen combined with one atom of oxygen be- cause water is so composed. Students of algebra will see that this sort of notation is like that in algebra, being no more than the use of co-efficients and exponents. Having this way of writing the names of elements in compounds, it is easy to express any substance chemically. To do this we have only to put the chemical elements that enter into it side by side. There is no rule as to the order in which the ele- ments are to be written, but certain orders have be- come usual. Thus OH 2 would likewise mean water, but it is not commonly so written. Just as a symbol represents one atom, so a for- mula represents one molecule. To express more than one molecule, the number of them is written before the formula. Thus to write four molecules of water, we put it thus : 4H 2 O. Where no figure THE ELEMENTS 71 follows a symbol in a formula, the figure 1 is, of course, understood. Thus HC1 would mean one atom of hydrogen combined with one atom of chlor- ine, and the whole formula means: one molecule of hydrochloric acid, as will be understood later. Certain methods that are used in algebra may be extended to the writing of formulae in chemistry. For example, if a compound acts as if it were an element, this is sometimes expressed by putting it into a parenthesis, or by separating the formula into groups by inserting a period. If a group of atoms is to be repeated several times, it may be enclosed in a parenthesis and a small figure put after it, just as if it were a single symbol. If the whole formula is to be multiplied, remember that the large figure precedes it all. In order to express the fact that certain chemical actions take place, it is usual to write them in equations, which are read exactly as if they were arithmetical or algebraic that is, from left to right. As the formula of any compound shows the number of atoms that are combined to make a mole- cule of that compound, and as no atom can ever be destroyed in making new compounds, a correct chemical equation must always be equal on the two 72 THE ELEMENTS sides; that is to say, if the number of atoms on one side are added together, they must equal the num- ber of atoms on the other side. Likewise, if we add together the weights of atoms in any compound, we shall have the weight of its molecule, since the formula represents one molecule. In an equation, likewise, the weight of the molecules put together must equal the weight of the molecules produced. In order, therefore, to use chemical equations, it is necessary for us to know the weight of each of the atoms. To the finding out of these weights for each of the elements has been devoted labor unim- aginable, by countless chemists ; and many of them are still somewhat uncertain. But for most of the elements, they are wonderfully accurate. Three tables, giving important facts about the elements first, a list of those that should be very familiar, then of those less well known, and then of rarer ones, are given on pages 74 and 75. Be- sides these there are many still rarer, which will be found in a complete table at the end of the book. This writing of chemical equations and the ex- pressing of chemical compounds by means of let- ters and numbers has been of the utmost value. It has led men to record and to remember the make-up THE ELEMENTS 73 of compounds, and, still more important, has led to the discovery of the laws by which compounds are made. It was thus ascertained that when a compound was separated into its elements, these elements were always found to exist in precisely the same proportion in the same compound. Thus in the case of common salt, chloride of sodium, as it is called chemically, no matter how much or how little salt was separated into sodium and chlorine, the relation of the amounts of these two to one another never changed. Sodium chloride has this formula, NaCl, and from what we have already said, you will understand that each molecule is made up, therefore, of one atom of sodium to one of chlorine. But the atomic weight of sodium is 22.88, chlorine is 35.18, and the weights of the sodium and chlorine in any amount of salt will always be to one another in the proportion that these numbers bear. Thus in 58 ounces of salt, there would be a little over 22 ounces of chlorine and a little over 35 ounces of sodium. If there were 58 tons, or 58 grains, the proportions of the two elements would not be changed, and if, on the contrary, we were to put together sodium and chlor- ine to make salt, the two elements would combine 74 THE ELEMENTS r^o s o >. OOO-* G t-5 fc-t-ODOS OOOt- COC5>-i5OT*OCO O O5t-5XOQO5i-HC5 cc CCi H 1-1 M 0) 5 i-HOiOiOOi >-H G* CM G* CO CO CO CO t-C*> 2 w S 5 " 2-3 M Nc;^ a ?_ 7 I _ ^"S >. _ si I II ll I fa * SB m 2j ^gali^l >5= H S ||||s| fl | fll^5|l| ilslll i It Miiiiiiiliiiiri 1 ii THE ELEMENTS 75 O s? X CO -H H O g *3 Bfl lillllllll g I 3 G III Tj* O l-H 5 fc- W b- I-H I-H O *O 05 5 CD O QQ 3 3 $ s s 1 M U O I O a s d .2 S I g S .3 3 llll 76 THE ELEMENTS with one another in these same proportions only. If there was more of one or the other, it would simply be left uncombined, for lack of a partner or set of partners. This is what has become known as the Law of Definite Proportions. The law of definite propor- tions was found by Proust. It was seen that it did not in all cases explain the action of the ele- ments, for at times the elements, though combining in definite proportions, combined in several propor- tions. By further observation, however, it was dis- covered by John Dalton that when an element com- bined in more than one proportion, the larger pro- portion was always a multiple of the smaller. Thus, supposing that the oxygen atom be repre- sented by its combining weight, 16, when it com- bined in other proportions than 16 it was found that these were multiples of the number 16 ; that is, it combined in 16, in 32, in 48, or in 64, parts, as if 1, 2, 3, or 4 of its atoms combined with other elements as if they were but a single atom. When this law was recognized by Dalton, it became known as the Law of " Multiple Proportions." * * In the combining of gases, advantage is taken of the fact that they have been discovered to combine in " volumes in simple THE ELEMENTS 77 This it was that laid the foundations of modern chemistry. Upon these laws scientific study of all compounds were based, for with them combination became a matter of fixed laws, not of untraceable chance. We shall now return to our study of the ele- ments, taking up next that most important one, carbon, because of its abundance. ratios to each other and to the volume of the product." That is, their relation is expressed by small whole numbers. Their volumes also are believed to contain, at the same heat and pressure, the same number of molecules. Thus they are com- pared with hydrogen, and weighed volume for volume. This gives the ratio of their weight to hydrogen as will be explained later. CHAPTER VI COAL AND CABBON COAL is so important a part of our civilization that, when only a few years ago, a strike on the part of the coal miners at that time put an end to the production of coal and caused it to become very scarce, it seemed as if there was no part of our daily life that did not depend upon it. Yet it is a substance that was almost unknown a few gener- ations ago. It is true that in books written about that time we see occasional references to the use of coal in an open grate, to make a luxurious fire, but it was not looked upon as a necessity. Ordinary heating was done, where it was done at all, by burn- ing wood. The work of the world was performed either by man or animal power, or by mills driven by wind or water. It was the increasing scarcity of wood and the increasing value of the steam-en- gine that suddenly gave to the deposits of coal an enormous value and set mankind to getting it out of the earth in great quantities. 79 80 COAL AND CARBON Being so much used, it was also more deeply studied, but in spite of all research that has gone to determine its origin, and of all the experimental science bent upon it, coal even to-day remains more or less of a mystery. The earliest idea considered it a mineral, which, of course, in a sense it is, but not in the sense that granite or flint is a mineral. It is, rather, a mineral in the sense that chalk is FOSSIL FOUND IN A COAL BED so-called that is, it is the remains of animal or vegetable life. The next belief that man held about it saw in it the compressed vegetable substances of past ages the wood and the leaves of old forests. This was a step nearer the truth, or what we now hold to be the truth. For, undoubtedly, coal consists of the remains of former vegetation, but instead of be- ing mainly the product of an age wherein flourished COAL AND CAKBON 81 great forests such as we now have, it is believed that coal is made up for the most part of the pollen dust that for thousands upon thousands of years, during the carboniferous age, was deposited from the gigantic ferns and similar plants that grew with amazing luxuriance in those hot, moist, and abso- lutely windless ages. Whatever may have been its origin, to the chem- ist coal is a veritable storehouse of treasures. It consists, it is true, to a very large extent of carbon the same substance that in other forms we know as the " black lead " of pencils (which nowadays is graphite, a nearly pure carbon) and in the diamond, which is simply pure carbon in crystal form. But, in addition to its greater proportion of carbon, coal has given rise to a vast number of other products. By being raised to a high heat in a closed vessel, the coal may be separated, or distilled, so as to give off fumes from which may be obtained various com- pounds and elements. We have already said that coal is a vegetable product, and that it consists largely of carbon. And the same is true of all vegetable matter. Car- bon is the foundation upon which all animal and vegetable tissues are built up. Owing to a strange 82 COAL AND CARBON peculiarity of the element, carbon, it has the ability to enter into an almost unending number of com- pounds. So complex are these and so puzzling, that in the science of chemistry the study of carbon com- pounds has been set apart as a separate branch. For many years, in the earlier days of the science, it was believed that a large part of these compounds SECTION OF COAL AS SEEN THEOUGH A MICROSCOPE could not be formed in the absence of animal life; that is, they must be the result of vital forces. It was therefore thought they were produced only in the tissues of living animals or vegetables. At a later date, however, chemists began to form these substances in the laboratory, and what had been called " organic chemistry " (that is, the chemistry of organic life) was studied under a new name the " chemistry of carbon compounds." f *J I fl *, Uj-ts M 1 Illfll s^ei ^s:sn s !f *i I Ell ; 2 B-1 lefSjiii ^tlis ^tif.ji 55||||LI||||1 gl^f*! r ^*l 0y Vnderwootl ,{ Underwood, New York. DRILLING COPPER ONE MILE UNDERGROUND. THE METALLIC ELEMENTS 141 copper wire in their circuits; in electric lighting and motors, and in electric railways. Copper is used also in all forms of printing, for the making of electrotypes and half-tone plates. It is of end- less use in household utensils, for sheathing ships, for coinage, nearly all of the cheaper coins contain- ing large parts of copper. In its alloys, the list of which is constantly growing, copper enters into jewelry, all brasswork, all substances composed of gun metal, phosphorus, bronze, aluminium bronze, manganese bronze, all anti-friction metals, and so on. Our nickel coins, so called, are three-fourths copper. The compounds of copper are usually very pois- onous. There are two main classes of these, known respectively as the cuprous and cupric. These two salts of copper are distinguished by the fact that one of them contains one half as much copper as the other, the cuprous salts containing the most. An important compound of copper is the copper sulphate, CuSO 4 , called "blue vitriol." This con- sists of blue crystals, soluble in water, and the solu- tion is much used where a simple compound of copper is necessary in chemistry. It is a most use- ful solution in electric batteries. Solutions of cop- 142 THE METALLIC ELEMENTS per are also used in spraying-mixtures for killing insects. Pigments derived from copper are Scheele's green, Brunswick green, and emerald green. Dangerous compounds of copper may form when copper articles are exposed to damp air. In moist air, copper unites with oxygen to some extent forming copper oxide, which unites with carbon dioxide in the air, forming carbonate of copper, a green compound. Vinegar (acetic acid) will form with copper, verdigris (or copper acetate) which is a poison. Other foods also may act to form poison- ous compounds, so copper vessels should not be used to hold food permanently. They should be tinned, nickeled, or otherwise protected. Owing to the poisonous nature of copper compounds, thje use of copper utensils in cookery requires that they be kept clean and polished, and that substances pre- pared in them be removed as soon as possible, to prevent the vegetable juices from acting upon the copper surface. The cuprous oxide (Cu 2 O) is a bright red pow- der. It imparts a splendid ruby red color to glass, and is used also in giving color to pottery. Thus it will be seen that the chief use of these copper compounds is as coloring matters, or as poisons. CHAPTER X METALLIC ELEMENTS, CONTINUED IRON AN important group of metals is formed of the three, iron, nickel, and cobalt. The two latter are seldom found separated. Iron is the most familiar, and, in the sense of being the most useful, may be considered the most valuable of all metals. Though known since very early times, there were long ages wherein copper and bronze played, imper- fectly, the part that iron was subsequently to fill. When iron was discovered, probably by the acci- dent of using its ores for the building of fireplaces, it began soon to take the place of the softer metals, copper, and its alloys, and the effect upon the his- tory of mankind was enormous. Iron, because of its superior hardness and stiffness, would take a sharper edge, would keep it longer, could be made into more slender tools with finer points, or, in the shape of wire or thin bands, was stronger and more rigid as a means of binding things loosely together or connecting them firmly. 143 144 THE METALLIC ELEMENTS The chief effect of the change to iron was an enormous gain of time in all mechanical work where tools played a part. For example, in clear- ing pieces of land from trees or bushes by means of iron or steel instruments, the work could be done in a small fraction of the time required when men had no better tools than those made of stone or even of copper. The nations or tribes that first learned to make weapons of iron and steel had an enormous advantage over their neighbors, and often con- quered them. When once discovered, also, iron proved to be much more plentiful than copper, more durable in use, and hence was, in effect, cheaper than the softer metal. When the history of mankind is divided into ages, as the Stone Age, the Copper Age, the Bronze Age, the Iron Age, and the Steel Age, we shall have covered in the list its whole history down to our own times, for we ourselves are living in the last of these. It is to steel, merely a stiffened and more elastic form of iron, that the greatest triumphs of our times are due. Steel beams give us our tower- ing city buildings, and our railroads, depending for their efficiency on steel rails and steel locomo- tives; our great ocean vessels have steel hulls and THE METALLIC ELEMENTS 145 engines; our rivers are spanned by steel bridges; and nearly every part of our lives is dependent upon steel, either for tools and weapons, for the instruments and machinery upon which it depends, or for the mechanisms by which these are made. Every improvement in the making of steel from iron vastly increases the power of mankind. Even the rarer metals most recently discovered largely take their value from the fact that they can be mixed into steel to change its qualities. From the steel pen that writes a letter, replacing the split reed or the shaped quill, to the great airship that is prom- ised for the next war, we are dependent upon iron and its compounds for all the 'arts of war and peace. Fortunately, iron is very plentiful, but it is sel- dom found in a pure state, except in meteorites. The compounds of iron, however, are found throughout nature in rocks, in many minerals, in the soil itself, in most natural springs, and even in the coloring matters that make plants green and blood red. The most abundant compounds of iron are hematite, a combination with oxygen ; limonite, where iron is combined with oxygen and hydrogen in a complicated way ; magnetite, another compound 146 THE METALLIC ELEMENTS with carbon and oxygen, and siderite, a com- pound with carbon and oxygen. Pyrites is a com- pound of iron with sulphur. There are other sul- phur compounds with iron also containing copper. Iron is particularly plentiful in the United States, mainly in the middle of the country and in the Lake Superior region. Chemists and engineers are constantly at work studying how to improve methods of extracting iron from its ores, and as a result, iron is constantly cheapened. The usual method of extracting iron from its oxide ores is to crush and grind the ores and then to subject them to intense heat, with coke or coal and limestone, in a blast furnace. Under the in- tense heat of a forced draft, the hot air causes the oxygen and carbon to unite, leaving the melted iron to collect at the bottom of the furnace. The fires in such a furnace may be kept burning for months, new ore being added at the top while the melted iron is every now and then run into sand moulds and allowed to cool in the form of rough slabs, or bars, called pig-iron. Iron produced in this way is not pure, but con- tains considerable carbon, phosphorus, and other elements. Owing to its impurities, cast iron is From Stereograph, Copyriytit 19C6, by Underwood tf- Fnderwood, New York. LOADING CARS WITH IRON ORE IN A TYPICAL MINE. THE METALLIC ELEMENTS 147 brittle and harder than pure iron would be. If the iron cools rapidly the carbon in it remains combined with the iron, giving it a light color. If BLAST FURNACE DIAGRAM Blast Furnace. A, throat; B, bosh; C, crucible where the melted iron collects; D, pipes for hot air blast; E, escape pipe for gases which do not escape through the "down corner " ; G, cup; H, cone; N, trough for drawing off slag; T, tuyere; I, hole through which iron is withdrawn. 148 THE METALLIC ELEMENTS it cools slowly, much of the carbon remains in the form of graphite, making the iron grey. The lat- ter is the sort ordinarily used in foundries, and is made into stoves, pipes, fences, the heavier parts of machinery, and, in general, all those things in which solidity is more important than elasticity. A purer form of iron, containing less carbon, is known as wrought iron, and has more of the quali- ties of steel, being tougher, more malleable, and softer. This is the form of iron seen in iron wire. It may be rolled into plates and sheets, made into rods, chains, horseshoes, and, generally, into those forms of iron-work where elasticity is desirable. It bends readily, does not break as easily as cast iron, and may be readily formed into delicate shapes. It is much used in artistic iron-work. Many things formerly made of cast iron are now constructed of steel, owing to the cheapness and exactness with which steel may be made of qualities to suit the most varied purposes. Wrought iron is made from ordinary cast iron by heating and thorough mixing so as to burn out much of the impurities. When brought to the right standard, the iron can be rolled and ham- mered into shapes convenient for use. The process THE METALLIC ELEMENTS 149 corresponds to that used by the smiths since early times in heating iron in their fires under a blast of air, and then hammering it into shape upon an anvil. Wrought iron contains very little carbon, and as it is the carbon that gives stiffness to iron, it can be readily understood that steel contains a larger proportion of carbon than the wrought iron. From Wurte's "Elements of Modern Chemistry.'* APPAEATUS FOB ROLLING STEEL To put the matter shortly, a very large proportion of carbon is found in cast iron ; a very little carbon is in wrought iron; adding a slightly greater pro- portion of carbon to wrought iron converts it into steel, which contains more than one and less than the other. The making of steel, however, is greatly modified by the presence of other elements beside carbon, and even by the method of its making. 150 THE METALLIC ELEMENTS Steel may be forged, or hammered, into shape, can be welded which is to say, two pieces can be united simply by being hammered together when heated. It is harder, stiffer, and more elastic than iron, and finds many more uses. Its most valuable and most remarkable quality is its power of being tempered. By heating the steel and plunging it into cold oil or water, it becomes exceedingly brit- tle and hard. If heated and cooled very slowly, it remains soft and malleable. In order to give it a quality between these two extremes, we have only to heat the steel, cool it until it is brittle, and then to heat it once more. If the second heating be checked at different points, we may obtain all varie- ties of hardness and elasticity. This reheating is known as tempering. As the steel is reheated it shows different colors upon its surface, and these changing colors tell just what the result of cooling the steel will be at each moment. Experiments have shown that the following colors are produced successively at the following temperatures : THE METALLIC ELEMENTS 151 430 Fahrenheit. Very pale yellow Lancets. 450 " Light straw color Razors and surgeons' instruments. 490 " Brownish yellow Scissors and chisels. 510 Purplish brown Axes and planes. 530 " Purple Table knives. 550 " Light blue Springs and saws. 560 " Dark blue Augers. 600 " Blackish blue Handsaws, hardest drills. By selecting the proper color, the hardness and toughness of the steel may be governed. For tools meant to be rather tough than hard, the heat is checked while the steel is yellow or brown. To make exceedingly hard tools for drilling or similar uses, the heating is checked only when the steel shows blue. There are many different substances used for cooling heated steel. The commonest, of course, is water, but many different kinds of oils, metallic solutions, animal fats, and even mercury, are em- ployed to give different qualities to steel. The effects of various elements upon steel may be gener- ally stated as follows: Carbon hardens and tough- ens the metal ; silicon hardens, but lessens the duc- tility, or the quality of being drawn into wire; 152 THE METALLIC ELEMENTS phosphorus makes steel brittle under shock, sul- phur makes steel difficult to work ; manganese, like phosphorus, seems to increase brittleness, if pres- ent in too great quantities; copper seems to do no harm unless sulphur is present with it ; aluminium, nickel and chromium toughen steel ; arsenic hardens it. It is believed that the best results are ob- tained when the steel is made entirely of iron and carbon, though small quantities of other elements often render steel suitable for special uses. The manufacture of steel, after what has been said, will be seen to consist in securing iron with the right amount of carbon. This can be done either by taking carbon from cast iron or adding it to wrought iron, either directly or by means of adding cast iron to the wrought iron. It is found easiest to add the carbon to wrought iron. This is done either by packing iron with carbon in tight crucibles, or by first burning carbon out from cast iron and then restoring, by adding to cast iron the right amount of carbon. This last is the method used in the Bessemer process, which, invented in 1860, has been most generally adopted and has been found to make steel of any desired quality cheaply and readily. The apparatus in which this is done is THE METALLIC ELEMENTS 153 known as a converter a great oval box large enough to hold several tons of melted iron. Through the molten iron air is blown, and the car- bon thus burned out, the oxygen of the air unit- ing with it forming the inflammable gas, carbon monoxide. This burns at once, keeping the metal CONVERTER melted, and after a few minutes only, the carbon and silicon and other impurities being thus re- moved, enough cast iron can be added to give any desired mixture of carbon. There is another process by which sulphur and phosphorus can be removed in a similar way. A third process consists in burning out impurities on an open hearth by means of a flame containing 154 THE METALLIC ELEMENTS much oxygen. This is known as the open-hearth process, and is especially useful in making tough and elastic steel, much used where it is meant to stand a great strain, as in cannon, parts of large machines, bridge beams, rails, and building beams. Pure iron is seven and eight- tenths times as MAGNETS HENRY'S (A). STURGEON'S (B) Sturgeon's was the early form, Henry's is the modern im- provement, by putting many turns of the wire on spools through which the poles are thrust. heavy as water. It is a metal having the remark- able quality of becoming instantly magnetic when surrounded by an electric current, and of losing this magnetism as soon as the current is withdrawn. Steel, on the contrary, once magnetized, retains the magnetism. It is believed that these two results depend upon the fact that in steel the particles, THE METALLIC ELEMENTS 155 once magnetized, arrange themselves in a fixed posi- tion, whereas, in iron, the position of the particles is retained only while the current is passed. The importance of this quality of iron can hardly be over-estimated. Most of the mechanical applica- tions of electricity depend upon it. To it we are indebted for the telephone, telegraph, dynamos, motors, electro-magnets, and all other applications of the electro-magnet. Pure iron in the presence of water or moisture rusts, that is, forms a ferric hydroxide, which is a complicated compound of iron, oxygen, and hydro- gen. Bust formed on the surface of iron does not prevent further rusting, but the rust will proceed until the whole mass of iron is changed to the ox- ide, because iron-rust and iron, when moist, make up an electric couple, and thus continue the rusting or oxidizing. This will be better understood after reading about electrolysis, later in this book. This makes it necessary to protect iron from the air by means of paints or oils, or by forming chemically upon its surface some compound of iron that will not further combine with the oxygen and hydrogen. The compounds of iron, like those of copper, are divided into two general classes according to the 156 THE METALLIC ELEMENTS amount of iron contained in them. They are known as ferrous and ferric salts. Owing to the fact that the ferrous salts readily unite with oxy- gen, they tend to change in the air into the ferric salts, and this same change can be hastened by the chemist, if he chooses, through the use of acids which bring about a rapid combination with oxy- gen. The ferrous salts tend to have a greenish color. Among them may be mentioned green vit- riol, which is used in the laboratory as a reducing agent, that is, an agent for removing oxygen from compounds. It also finds commercial use in the making of dyes and inks. The inks which are made from iron salts combined with tannin are, in gen- eral, of two classes ; one which writes black at once, and another which becomes black after drying, ow- ing to the action of the oxygen in the air upon the iron. Ferric salts tend toward reddish brown and pale violet in color. Thus the ferric oxide is a brown- ish-red salt which is used to make chalk, and red ochre in painting. It is also a polishing material and gives color to porcelain and glass. These colors vary according to the treatment. The ferric hydrate is yellow ochre, and may be considered sim- .From Stereograph, Copyright 1906, &y Under woorl ,f- Underwent, New York. OPEN PIT IRON MINING. THE METALLIC ELEMENTS 157 ply as iron rust. Besides these, there are a ferric sulphate, ferric chloride, and other compounds, from the simplest to those whose composition re- quires the deepest study. There are hundreds of compounds of iron, but we may say, in general, that besides their uses in the laboratory, they are mainly employed in medicine and in making dyes and inks, and in photography. Their value con- sists in their coloring property, in their affinity for oxygen, and in the solubility of many of them in water. COBALT AND NICKEL Cobalt is a metal discovered in 1733. It has a white, metallic lustre, somewhat resembles iron in hardness, but is more fusible and less magnetic. It has an affinity with oxygen, and thus rusts in the air, though to a less extent than iron. The metal, when pure, is rare, being usually found com- bined with nickel, with arsenic, or with antimony. It has no especial use yet discovered. It forms salts with nitric, hydrochloric, or sulphuric acid, and these are reddish in color, but become blue when heated, the heat driving off the water con- tained in their crystals. 158 THE METALLIC ELEMENTS Cobalt combined with silica forms a coloring matter known as smalt, a beautiful blue color used in coloring pottery and glass. Cobalt gives other valuable pigments for painters and in the arts generally. Nickel somewhat resembles both iron and cobalt, but is commoner than the latter. The quality that makes it most valuable is the fact that it retains its brightness in the air, that is, it does not combine with oxygen. Nickel is also used as an alloy with copper, a very small quantity serving to lighten the color of that metal. Alloyed with brass, nickel gives us German silver, a valuable alloy because of its resistance to oxygen, or because it does not rust. Nickel is added to steel, to which it gives the greatest toughness. A little over three per cent, of nickel has been found to make the best alloy of steel for manufacturing armor plates and parts of machinery where extreme strength is requi- site. An every-day use of nickel with which we are all familiar is in nickel-plating. This, because of the high polish which nickel takes, not only ren- ders manufactured articles attractive, but it is use- ful as well, since it protects steel and iron from rusting. Nickel-plating is sometimes applied to THE METALLIC ELEMENTS 159 zinc, thus giving an alloy which is capable of re- ceiving a very high polish and at the same time is light and durable, while it is easily moulded into articles from sheet metal. Nickel and iron are likely to occur pure only in meteorites. Like iron, nickel may be welded when free from carbon, silicon, and other impurities. In general properties iron and nickel resemble one another closely, differing only in their affinity for oxygen. CHAPTER XI METALLIC ELEMENTS, CONTINUED PLATINUM PLATINUM is a very heavy metal, with a strong resemblance in appearance to silver, though it is greyer and does not take so high a polish. It is found in an ore which contains also five exceed- ingly rare metals in small quantities. These are ruthenium, osmium, iridium, rhodium, and palla- dium. Iron, gold, and copper are often found associated with these. Most of the platinum ore comes from Russia, though small quantities are found in the United States, South America, and other countries. The name is derived from the Spanish, plata, which means silver, and was given because the metal was supposed long ago to be a form of silver ore. The ore occurs in the form of grains or scales, and is at first treated with strong acids to remove gold, silver, and copper. This changes platinum into a solution which contains some iridium. By adding ammonium chloride the 161 1G2 THE METALLIC ELEMENTS platinum is precipitated and may then be ham- mered into sheets. Owing to its strong resistance to nearly all acids, platinum is used in the laboratory for making cru- cibles, stills, dishes, and other vessels to contain acids that would attack other metals. Platinum also resists heat, and may therefore be used in heating compounds when vessels made of other materials would be melted. A very important use of platinum depends upon the fact that when heated, or cooled, it expands and contracts to prac- tically the same degree as glass. Consequently it may be used in connecting electric-light bulbs to electric wires. When the current passes into the bulb it heats the connecting wires, and these ex- pand. If these wires did not expand and contract at the same rate as the substance of the glass bulbs, they would either cause the bulbs to crack, or would admit air, thus destroying the vacuum. But where platinum is used, the joint remains tight. No other metal has been found to take its place for this purpose. Platinum is used also by dentists, owing to its resisting power to corrosion. For the same reason it is used in jewelry, making a good contrast with THE METALLIC ELEMENTS 163 gold and furnishing exactly the right setting for certain jewels. Owing to its use in electric work, the demand for platinum largely exceeds the sup- ply, and its price is continually increasing. Plati- num is exceedingly heavy, even heavier than gold, being twenty-one times as heavy as water. There are only a few elements which are heavier, such as osmium and iridium. Platinum conducts electricity, but has a very high resistance, which causes it to give out a large amount of light and heat. Platinum is largely used in photography because of its beautiful black color when minutely divided, and its permanence, owing to the fact that it does not tarnish or oxi- dize. The chief obstacle to its use for the making of photographic prints is its rarity and very high price. A peculiar property of platinum, while in the spongy state, or when very finely divided, is the ability to absorb very large volumes of gases. The absorption of gas is so rapid that heat is given out rapidly enough to set fire to the gas. This same property is found in palladium. It is known as occlusion. Owing to this property, small quanti- ties of platinum are sometimes used to make light- 164 THE METALLIC ELEMENTS ers on gas-burners. As soon as the gas is turned on, its absorption by the platinum begins, the plati- num is soon red-hot, and the gas takes fire. A pocket cigar-lighter is made on the same principle. A small metal box contains a wick saturated with a liquid that gives off gas readily. Another com- partment of the box holds a bit of platinum wire, which, by being thrust into the fumes, becomes heated and ignites the vapor, as already explained. Of the rarer metals often found with platinum, palladium is sometimes used in the laboratory be- cause of its ability to absorb gases, especially hydro- gen ; osmium is used in a certain form of electric light and in chemical work under the microscope; while iridium is used in making an alloy to tip gold pens, as it is intensely hard and almost un- wearable. Some chemists make a large group of nine metals, which they call the platinum group. In this are included iron, cobalt, ruthenium, rho- dium, palladium, osmium, iridium, and platinum. They are grouped together because all are hard, white, not easily melted, and, excepting iron, are not attacked by the air. To finish the discussion of this group by a few words about the rarer metals, ruthenium is called THE METALLIC ELEMENTS 165 the rarest of the elements; rhodium also is very rare ; palladium has interest for us mainly because of its property of absorbing hydrogen. This ab- sorption increases the size of the mass of metal and takes place, as has been said, rapidly enough to cause a high temperature, as in the case of plati- num. Kadium is still being studied, and therefore cannot be finally assigned its place in a table or system of elements. ARSENIC Arsenic, when pure, is a brittle, grey solid, about five or six times heavier than water. When heated it changes to vapor, with a smell like that of garlic. Its chief practical use is to form poisons for ani- mals, as a drug, in minute quantities in medicine, and to harden lead, a very small portion being added to the lead from which shot is made. Ar- senic also occurs in many green paints, enters into the manufacture of glass, and is especially useful in preserving skins from the attacks of insects. Paris-green is a common insect poison, containing a large quantity of arsenic. The symbol for arsenic is As. In spite of the fact that the element arsenic itself is not poisonous, its compounds are among the most poisonous of all substances. Fortunately 166 THE METALLIC ELEMENTS it can be readily detected, even in the most minute quantities. Arsenic coloring matters are very dan- gerous. In wall papers or clothing or draperies, the arsenic may become detached and be absorbed or breathed as a gas. For this reason brilliant green colors in food, dyes, wall papers, and so on, should be avoided unless they are known to be free from arsenic. Symptoms of arsenic poisoning are dryness of the mouth, headache, and nausea, or, if the poison takes the form of a gas, muscular pains and inability to sleep. ANTIMONY The symbol for this element is Sb, from the Latin name stibium. It is a silver-white solid, found usually in crystals, a little heavier than arsenic. As it expands instead of contracting when cooled, antimony is added to type metal so that the metal on cooling may fill up the tiniest parts of the mould, forming perfect type. Antimony is also used in the alloys known as Britannia metal and Babbitt metal, and with bis- muth, it forms a very effective thermopile. The thermopile is a means of causing electricity to be produced by heating or cooling two metals joined THE METALLIC ELEMENTS 167 together, an arrangement often found useful in cer- tain apparatus. Excepting these uses, antimony is found commercially useful only in making some kinds of matches and fireworks, and in the prepa- ration of rubber. It is also one of the constituents of tartar emetic. LEAD Lead has been known since the earliest days, being called plumbum by the Romans, which gives us our symbol for the element, Pb. It is occasion- ally found pure in nature, but the most abundant ore is galena, which is lead sulphide, and it is from this ore that the lead of commerce is derived. A large quantity is produced in the middle west of the United States. The ore is subjected to heat in a furnace, and the metal readily separates from the sulphur, which combines with oxygen, or sometimes with iron, which is added for the purpose. Lead is also separated from the galena by the electric current, using sulphuric acid as the electro- lyte. It is a bluish metal, showing a bright surface when cut or scraped. It soon tarnishes in the air by forming an oxide, but once formed, this coating protects the metal within. It is the heaviest, ex- 168 THE METALLIC ELEMENTS cept mercury, of the common metals, and melts readily at a low heat. The salts of lead are poisonous, and if taken into the body gradually accumulate there, with serious effects. Commercially, lead finds its greatest use in piping, made by forcing lead through a hole in which is a core. This piping is used both for conveying water and to cover the wires that con- duct electricity. It is also used, of course, in the making of shot and bullets, though these are nowa- days often alloys. To make type metal, lead is alloyed with anti- mony, because the latter metal has the property of expanding while cooling, as already mentioned. Massicot and litharge are the monoxides of lead (PbO), and are used in oils and varnishes and in making glass. Ked lead (Pb 3 O 4 ) is used in making glass and as an artists' paint. The cheaper form of red lead is often used as a priming, in painting, to protect iron structures from rust, and also to make tight the joints of lead pipes. The old name was minium, and the use of this red color by il- luminators for initials in books written by hand gives us the word " miniature," applied at first to small ornamental pictures that went with the red initial letters. THE METALLIC ELEMENTS 169 White lead is a lead carbonate (PbCO 3 ). It is a heavy white powder, used as a white paint when mixed with linseed oil. It is prepared by many processes, the older processes being very slow, but the electric process is rapid and said to be as good. Sugar of lead is the lead acid formed by the ac- tion of acetic acid upon lead, or lead oxide. It is exceedingly poisonous. There are many other com- pounds of lead, but they are less important. TIN Tin is one of the oldest of the metals, the mines in the British Islands having been known long be- fore the Christian Era, being visited by the Phoeni- cians. The islands, indeed, were known as the Cassiterides, or Tin Islands, from the Greek word Kao-o-tVe/oos. The Latin name for the metal is stan- num, which gives us the symbol Sn. While softer than zinc, it is harder than lead, and a little over seven times as heavy as water. As it is not easily affected by air or moisture or weak acids, a coating of it is used to protect sheet iron, which forms " tinware." The so-called tin foil should be made of hammered tin, but is usually formed partly of 170 THE METALLIC ELEMENTS lead. Tin is used largely to make alloys with copper, and lead with tin forms pewter and solder. When a bar of pure tin is bent, it produces, owing to the crystals present, a peculiar noise, known as the " cry " of tin. MERCURY, ZINC, MAGNESIUM, AND CADMIUM Mercury is the metal that exists in liquid form at ordinary temperatures. Its symbol is Hg, and its common name is, of course, quicksilver. The symbol comes from the Latin name, hydrar- gyrum, which means water silver. Mercury has been known since the earliest days, and occurs mainly in the important ore, cinnabar, especially abundant in Spain. The mercury is extracted from this ore, which is a sulphide, by heating, whereupon the sulphur combines with oxygen, and the mercury is changed to vapor, and may then be condensed. Pure mercury is a bluish white liquid, which boils at 674 degrees Fahrenheit. It does not freeze until the temperature reaches about 35 below zero. It is nearly fourteen times as heavy as water. It is one of the elements each molecule of which consists of a single atom. It is used in the extraction of THE METALLIC ELEMENTS 171 gold and silver from their ores, to make barometers and thermometers, and especially in the so-called mercury pump, used to extract the air from incan- descent bulbs. When made into an alloy, it is called an amalgam. Amalgams are used in tinning, gilding, and silvering, to cover the zinc plates in electric batteries, and to protect metals from rust- ing. In medicine, mercury is a most important drug, especially used in blood-poisoning and in liver troubles, being the chief constituent of calo- mel. Mercury is, however, a poison to the system, producing palsy, salivation, and other symptoms. Another use is the silvering of mirrors, for which purpose mercury is made into an amalgam with tin. Amalgams made with silver or platinum are used by dentists for filling teeth. Mercury chloride, the common name for which is corrosive sublimate, is a white solid, with acid properties, exceedingly poisonous, but used in minute quantities in medi- cine, being one of the very best antiseptics. Mer- cury iodide is used as a paint. The sulphide, cinnabar, occurs in two forms, red and black, the latter being artificial. The red, when pure, gives the brilliant " vermilion," whose uses are manifold. Fulminating mercury is a com- 172 THE METALLIC ELEMENTS plicated compound, with the formula, HgN 2 C 2 O 2 . It is a white powder, used to make percussion caps, and so easily exploded that the very slightest dis- turbance, such, for example, as removing the cork from a bottle, is sometimes sufficient to set it off. ZINC With mercury are often grouped zinc, magne- sium, and cadmium. Zinc ores are combined with sulphur, carbon, silicon, and oxygen. The sulphur compound is found in Missouri and Kansas. The zinc is separated from its ores by heating with charcoal, and the liquid zinc is then vaporized and cooled again to separate impurities. It is a shiny white metal that is brittle until it has been worked over. Though it does not tarnish readily, grad- ually it darkens in the air. It finds an extensive use in electric batteries, for which purpose it is coupled with copper or with carbon to make the two poles. Sheet zinc is used to line tanks, or to protect walls or floors from heat. The coating of zinc on iron is used to pro- tect it from rust, and such iron is commonly known as galvanized. Zinc enters into many alloys, and also forms the.basis for a white paint. It is very THE METALLIC ELEMENTS 173 permanent because it does not change when exposed to the air. Zinc sulphate is used in medicine, and also in dyeing and cloth-printing. A wide use of zinc in sheets is in roofs, gutters, ornamental cor- nices, and so on. A chloride of zinc is injected into wood to prevent decay. An oxide of zinc, already spoken of as being used as a pigment, is also some- times used for tooth filling. The symbol of zinc is Zn, and it melts at a little above the temperature at which coal lights, being less fusible than lead or tin, but far more fusible than iron. CADMIUM Cadmium, the symbol of which is Cd, is often found in zinc ores, from which it is separated before the zinc, being more easily made volatile. It re- sembles tin in color, and is more malleable and ductile than zinc. It melts at a slightly higher temperature than lead. The chief use of cadmium is in cadmium sulphide, a bright yellow solid used as a pigment and making a brilliant and permanent yellow. Cadmium also forms certain alloys that melt readily. MAGNESIUM Magnesium (Mg) is found very widely distrib- 174 THE METALLIC ELEMENTS uted in its compounds, and is so abundant as to form over two per cent, of the earth's crust. In the upper Mississippi Valley a magnesium calcium car- bonate, called dolomite, and resembling marble and limestone, forms vast deposits, and even mountain ranges. Magnesium is found in many silicate rocks, and also in sea water and mineral springs. It is named from its occurrence in Magnesia, a district of Thessaly. Its melting point is high, about 806 Fahrenheit. Magnesium occurs in talc and in soapstone, a more compact form of the same mineral, also in asbestos. Magnesium sulphate, known as Epsom salts, is found in many springs in the neighborhood of Epsom, England. Some compounds are used as fertilizers, and in making medicines. Two striking properties of magnesium are its lightness, and the fact that it burns readily, giving a most brilliant light, often used in flashlights for photography, and also formerly in magic lanterns. Phosphates of magnesium occur in the bones of animals, in grains, and seeds, and in guano, which renders the latter valuable as a fertilizer. Magne- sium oxide, often called magnesia, is used in medi- cine as an antidote for poisoning with mineral THE METALLIC ELEMENTS 175 acids, and since it hardens on exposure to the air when mixed with water, is a useful compound in forming artificial stones, or gems. ALUMINIUM OR ALUMINUM Next to oxygen and silicon, compounds of alu- minium are most plentiful in the earth's crust. Feldspars, mica, clay, and slate are the commonest minerals in which aluminium is found. It forms about eight per cent, of the earth's crust, and is therefore the most abundant of the metals. The metal was first obtained, in 1827, by Wohler. It was prepared also in 1854 by Ste.-Claire Deville. Sir Humphry Davy, on account of the relation of this metal to alum, proposed that it be named alu- mium. Later it was called aluminum, and finally aluminium. Although such vast quantities were known to exist, the difficulty of extracting it was so great that the metal at first obtained was hope- lessly expensive. In 1885, at the International Exposition, a small bar of aluminium was exhibited in a glass case, labelled " The silver from clay." The showing of so large a mass of aluminium was the result of a century's hard work by chemists. The metal occurred in alumina, where it was com- 176 THE METALLIC ELEMENTS bined with oxygen. In 1824, (Ersted^ discovered a way to make a compound of chlorine and alumin- ium, and from his compound, Wohler, three years later, by the use of metallic potassium, separated the aluminium, since the potassium combined with the chlorine. The metal as separated was a fine powder, which could not be brought to unite, and this powder remained a chemical curiosity for twenty-seven years. In 1854, Deville, by a slight change in Wohler's process, obtained a button of aluminium, instead of the powder. But this button cost more than its weight in gold. This same chemist then attempted to decompose the chloride of alu- minium by means of the electric current, and thus obtained enough to make a small rod. But in those days the cost of electricity was too great to make the experiment a valuable one. Deville next used sodium, instead of potassium, and this time obtained a large quantity of alu- minium at less expense, part of which was cast into the bar displayed at the Exposition, and another part was made into a rattle and presented to the Prince Imperial. A little more of the same metal was cast into eagles for the flagpoles of the French THE METALLIC ELEMENTS 177 army, and made into a helmet for 'the King of Denmark. No longer ago than 1855, was aluminium thus an almost priceless gift offered to the son of an emperor. To-day, it is cheap enough to meet wide use in kitchen utensils made of precisely the same metal. By 1860 aluminium was being sold for six- teen dollars a pound, but no improvement of impor- tance was made for a quarter of a century. Other investigators tried to improve the process, but it was not until recently that the improvement in electric machines and the cheapening of the cur- rent so greatly cheapened the metal. Without following further the many improve- ments that cheapened its production, we come to what is known as the Hall process, in which elec- trolysis made easy and cheap the production of hundreds of pounds a day. The cost of aluminium was quickly reduced to less than fifty cents a pound, and even this was not the limit to the cheapening. Aluminium is only two and a half times as heavy as water, or about one-third the weight of iron. Its lightness is enormously important, and millions of pounds of the metal are produced a year (nearly all at the electric works at Niagara Falls). It is ITS THE METALLIC ELEMENTS easily drawn into wire or hammered into plates, though it needs to be annealed frequently. It is an excellent conductor of electricity and heat, and its tensile strength is about equal to that of cast iron. Though readily cast and welded, it can be soldered only after taking great precautions to bring together only clean surfaces of aluminium. It is very slightly affected by the air, and is little affected by many acids. Clay would be a cheap and an inexhaustible source of the metal, except for the presence of impurities, such as iron, silicon, and various metals which make the aluminium brittle. It is hardly necessary to tell the manifold uses to which the metal has been put, either for orna- mental purposes, in making protective paint, or for light metal fixings of every kind. It forms several useful alloys. Corundum and emery are oxides of aluminium. Many of the precious gems are mainly aluminium with coloring matter. The sapphire, the ruby, topaz, amethyst, and emerald (the latter three in the precious " Oriental " variety) are all crystallized aluminium oxide. Turquoise is alu- minium phosphate; the emerald is an aluminium silicate; the garnet also contains silicate of alu- minium. THE METALLIC ELEMENTS 179 Alum is a compound containing aluminium sul- phate and potassium sulphate. It is the general type of other compounds resembling it, also known as alums. These are very soluble in water, and find a wide use in dyeing, calico printing, in tan- ning, in making paper, and in fire-proofing wood and cloth. An important use of alums is the fixing of dyes in cloth, they being then known as mordants. The mordant is used to wet the cloth before it is printed with the dye, and unites with the dye in such a manner as to form a coloring compound that is per- manent, or a fast color. The clay which will make pottery is aluminium silicate, and ordinarily contains many impurities. According to quality, the pottery is divided into three classes, porcelain, stoneware, and earthen- ware. Aluminium fuses at 1292 degrees Fahrenheit. An important alloy is aluminium bronze, which is hard, malleable, and tough as steel. Aluminium filings, with mercury chloride and potassium cyanide, are put together in such a way as to produce great heat by their combination. Then water is added at such a rate as to reduce the 180 THE METALLIC ELEMENTS temperature to about seventy degrees. The heat taken up by the water causes it to separate, the oxygen uniting with the compounds and pure hydro- gen being set free. This method of procuring hydrogen is in use in Paris for the purpose of pre- paring hydrogen for balloons. A modern application of the readiness with which oxygen combines with aluminium is known by the name, Alumino-therniics. A mixture of aluminium and some oxide such as iron rust, when lighted by the magnesium ribbon burns throughout its entire mass with a fierce heat equal to that of the electric arc. This intense heat is used in manufacturing tools of chrome steel, in welding trolley rails, espe- cially the third rails that convey electricity, and also may be used on shipboard to weld large cast- ings such as stern-posts and propeller-shafts, when broken. The thermit can be applied to the break without removing the broken piece from its place, and produces as strong a welding as would be pos- sible in a steel foundry. MANGANESE Manganese, although not found pure in nature, exists widely in its compounds, from which, in its THE METALLIC ELEMENTS 181 oxides especially, it is readily reduced by roasting with charcoal. It has a high melting point, about 3500 degrees Fahrenheit, and is about seven and a half times as heavy as water. When separated, the pure metal is grey, hard, and brittle, with a lustrous surface. Both physically and chemically it resembles iron in many respects, entering into similar combinations. It is especially useful in forming alloys, an instance of which is " spiegelei- sen," a valuable form of iron alloyed with man- ganese. It forms many oxides which are found in nature. These find employment in dyeing and in medicine. Manganese also in some compounds acts like an acid, and gives rise to manganates and perman- ganates, of which those of potassium are especially important, being used in the laboratory as powerful absorbents of oxygen, especially the permanganate, which acts with great energy. This latter forms the basis of a disinfectant known by the name, Condy's fluid. Copper and iron with manganese form man- ganese bronze, an exceedingly strong and tough alloy, possessing many of the best qualities of steel, valuable because it does not oxidize, or rust. A 182 THE METALLIC ELEMENTS notable use of this metal is the making of pro- pellers. A compound which is most important and abundant is manganese dioxide, MnO 2 . This, when heated, sets free oxygen, and by the use of hydro- chloric acid may be made to set free chlorine. This dioxide is much used to whiten ordinary glass, in which it neutralizes the green tint. CHROMIUM Chromium also is found in compounds, never free, but traces of it occur in many minerals. Un- til the intense heat of the electric furnace was used, it was extracted with great difficulty. It is a lustrous grey metal, with a shiny surface when polished. It is slightly lighter than manganese and melts only in the electric furnace. If a large pro- portion of chromium be added to steel, it makes a hardened steel, useful where the greatest resisting power is needed, as in battleships, safes, and min- eral-crushing machines. With potassium, chro- mium forms compounds, soluble in water, that are valuable as oxidizing agents. Chrome-alum, a compound with sulphur and potassium, is like ordi- nary alum except that chromium replaces the alu- THE METALLIC ELEMENTS 183 minium. It is used in dyeing and tanning. Lead chromate is the chrome yellow which is the basis of the pigments called chromes. These are yellow, orange, or red. There are three rare metallic elements that may be classified with chromium. These are molyb- denum, tungsten, and uranium. The first enters into certain laboratory compounds. Tungsten is sometimes used as a hardener of steel, and fur- nishes in sodium tungstate a fire-proofing mixture for cloth. It has recently proved to be exceedingly valuable for making filaments in incandescent elec- tric lights. It needs a peculiar kind of support, and at present the filament is rather brittle, but if care be used it proves to be a most economical and effi- cient filament, giving better light at a much de- creased cost, when compared with the ordinary car- bon filament. Over a million tungsten lamps are in use, and about seventy-five thousand a day are being made. It is also used in making incandes- cent mantles. URANIUM Uranium, the heaviest of all the elements, is of great scientific interest, but practically is used 184 THE METALLIC ELEMENTS chiefly to color glass, to which it gives the color green by transmitted, yellow by reflected, light, BISMUTH Bismuth, though a rare metal, is found free in nature and needs only to be purified. Its color is greyish white, with a reddish tinge, and it is brittle. It is nearly ten times heavier than water, and melts at a slightly higher temperature than does tin. Mixed with lead and tin, it forms alloys that melt at very low temperature, and find a use as safety plugs, which at a comparatively low temperature will melt. They are used in steam boilers, to pre- vent short circuits in electric apparatus, and in devices against fire, as in the automatic sprinklers of large buildings. Bismuth and antimony form an excellent combination for thermopiles, that is, when heated, an electric current is set up between the metals. Bismuth finds a small use in medicine. STRONTIUM AND BAEIUM Strontium and barium are rare, and resemble calcium in many respects. The pure metals do not occur free, and find no striking uses. Their com- pounds are abundant. Thus strontium hydroxide THE METALLIC ELEMENTS 185 is used in the manufacture of beet sugar. Stron- tium nitrate enters into the making of red fire. Barium salts have a similar use in making green fire. Both of these metallic elements, combined with sulphur, are used in making luminous paints. GLUCINUM Glucinum is a silver- white metal, light in weight, resembling magnesium. It never occurs free, but is usually found combined with silica, or alumin- ium, or both. It is found in emeralds, and in the beryl, of which emerald is a species. Its salts have a sweet taste which gives it its name, from the Greek word glukus, sweet. Glucinum is also called beryllium. NITROGEN, PHOSPHORUS, ETC. We have already, in speaking of the composition of the air, discussed to some extent the properties of nitrogen, especially looking upon it as an inert gas that serves to dilute oxygen and prevent its too energetic action. But nitrogen also plays a most active part in its compounds, and especially in nitric acid and ammonia. It is obtained, as has been said, by removing oxygen from the air, and by 186 THE METALLIC ELEMENTS taking advantage of the attraction of phosphorus for oxygen, or by allowing liquid air to evaporate a process which to some extent separates the two gases composing it. AMMONIA Speaking now of its compounds, we shall take PBEPARATION OF AMMONIA M, N, O, cylinders containing solutions of impure ammonium chloride, as obtained from coal gas factories, mixed with lime; S, S, S, stirrers to keep the lime from settling; F, furnace to heat the mixture and expel the ammonia; B, B, condensers for cooling the ammonia gas; C, cylinder of pure water to absorb the ammonia and thus form aqua ammonia; D, trough of acid to combine with- any fluid escaping from C. In this trough if hydrochloric acid is used, there would form ammonium chloride. up first ammonia, which common term is applied both to a gas and to the solution made when the THE METALLIC ELEMENTS 187 gas is dissolved in water. Ammonia is formed nat- urally by the decaying of animal or vegetable mat- ters that contain nitrogen. Moisture supplies hydrogen that unites with this nitrogen, forming the gas ammonia. One method of preparing am- monia, formerly much used, was the heating of horny substances, such as hoofs and horns, in a closed vessel, and this gave rise to the name still popularly used for ammonia spirits of hartshorn. The formula for ammonia gas is NH 3 . Since the ammonia gas is lighter than air, it is collected in the same manner as hydrogen by allowing it to flow upward into a vessel from which it displaces air. Ordinarily, ammonia is prepared by mixing this gas with water, which readily absorbs it. The ammonia in the market is usually that produced by the distilling of coal in making illuminating gas. The solution is correctly known chemically as ammonia hydroxide. Ammonia is colorless, with a sharp, choking odor that makes it dangerous to inhale. It is only half as heavy as air, and readily separates itself from solution if left exposed. Ammonia can easily be condensed to a liquid form if reduced to a low temperature under compression. When liquefied, 188 THE METALLIC ELEMENTS it readily evaporates, absorbing much heat as it changes to the gaseous state, and is therefore widely used in refrigeration, as in making artificial ice. The solution is a very strong alkali, so strong as to be called one of the caustic alkalis. It neutralizes acids, causing the formation of salts. These salts have a peculiar chemical formula. In them is found a group of atoms expressed by NH 4 . This group acts chemically as if it were a metal, and has been given an especial name, ammonium. It can be separated from compounds, since it at once sepa- rates into ammonia gas and hydrogen. This group of one atom of nitrogen and four of hydrogen, is one of those known as a radical, because it is, as it were, a root for the formation of ammonia com- pounds, seeming to attach other atoms to itself, and yet to retain its formation as a group. This group is found in several salts. With chlorine it makes ammonium chloride; with sulphur, ammo- nium sulphate. The hydrochloride is used in elec- tric batteries and in several industries. It is com- monly called muriate of ammonia, because muri- atic, or hydrochloric acid, is used in its prepara- tion. It is a crystalline solid that dissolves readily in water. When heated gently, it turns to vapor, THE METALLIC ELEMENTS 189 which is condensed upon the cooler surface of the upper part of the apparatus and can then be col- lected. This method of treating a solution so as to obtain a solid from, it is called subliming, or subli- mation. The result of so treating ammonium chlo- ride is to produce sal ammoniac. Ammonium sulphate is used in fertilizers; am- monium hydrate is used in the preparation of ni- trous oxide, or laughing gas, so called because, when it is used in producing insensibility, during the first stages of its inhalation it causes a cer- tain pleasurable excitement often expressed by laughter. Ammonia is used as a slight stimulant when in- haled, is very valuable as a cleansing agent, in refrigerating mixtures, and as a dye-stuff. NITRIC ACID Nitric acid is prepared by heating sulphuric acid with some salt containing nitrogen; for example, sodium or potassium nitrate. The chemical for- mula expressing this formation is as follows: NaNO 3 + H 2 SO 4 = HNO 3 + HNaSO 4 , the HNO 3 being the nitric acid. Nitric acid is very strongly corrosive, causing 190 THE METALLIC ELEMENTS serious burns to the skin. As it parts readily with its oxygen, especially when warm, and this oxygen combines with most other substances, these are truly burned by the acid. Thus wood or charcoal may be charred by nitric acid as if in a fire. It attacks the softer metals readily, and is therefore APPARATUS FOB THE MANUFACTURE OF NITRIC ACID Nitric acid is manufactured on a large scale by heating sodium nitrate and sulphuric acid in a large cast-iron retort A, con- nected with huge glass or earthen-ware bottles B, B, B, ar- ranged as shown. The last bottle is connected with a tower filled with coke over which water trickles to absorb the vapors which escape from the bottles. The acid vapors are also often absorbed in earthenware or glass tubes. used in etching. The etcher covers a plate of cop- per or zinc with wax, removes portions of the wax where he wishes lines to be bitten into the metal, and then covers the plate with nitric acid, usually diluted. The wax protects parts of the metal, the uncovered lines being bitten in by the eating away THE METALLIC ELEMENTS 191 of the metal by the strong acid. Owing to the activity of nitric acid in combining with metals, older chemists named it aqua fortis, or strong liquid. The action of the acid with the metals forms nitrates, or oxides. Nitrogen forms five compounds with oxygen, but the only one popularly known is the laughing gas, nitrous oxide, already spoken of. PHOSPHORUS Phosphorus, the second number of the nitrogen group, is known to us mainly through the occur- rence of phosphorus in nature, and compounds of phosphorus are found in the brain, nerves, and bones of animals. Like sulphur, phosphorus is allotropic, existing in three forms, yellow, red, and black. The yellow phosphorus is not unlike wax, though it becomes brittle when cooled. It readily takes fire in air at a temperature of 34 C., and often at a lower temperature than this will give off white fumes. As is generally known, phosphorus, slightly dampened, glows with a bright yellow light, as may be seen by slightly moistening and rubbing the head of an old-fashioned match in a dark room. Pure phosphorus, owing to its readiness to take 192 THE METALLIC ELEMENTS fire, has to be kept under water, and must never be handled in the air. The red phosphorus is made by heating the ordinary form in a closed vessel. i t n MANUFACTUBE OF PHOSPHORUS R, R, R, are the retorts into which the mixture of charcoal and phosphorus compounds are put; F is the furnace, and W, W, the water tanks where the vaporized phosphorus is condensed. The black may be prepared by dissolving red phos- phorus in melted lead, and then allowing it to crys- tallize as it cools. Phosphorus is used mainly in the manufacture of matches, and also in poisons for destroying ani- THE METALLIC ELEMENTS 193 mals. While the yellow phosphorus is used for the old-fashioned friction matches, the safety match also uses red phosphorus in the prepared surface upon which the matches are to be struck. Since phosphates are found in plants, especially in the fruits and seeds, vegetation is constantly using up the phosphorus in the soil, and this must be re- placed if the land is to be kept fertile, by com- pounds containing phosphorus. CHAPTER XII SOME OTHER METALLIC ELEMENTS SODIUM and potassium, together with three rare elements, lithium, rubidium, and caesium, are usu- ally classified together, and though they have the character of metals, they seem to differ from other metals in possessing strong alkaline properties. SODIUM Sodium, the first of these, for which the symbol is Na, from the Latin name natrium, is found most abundantly in common salt, sodium chloride, and in a nitrate, though the carbonate also is common. Something over two per cent, of the earth's crust is composed of sodium, which is about as abundant as aluminium. Sodium, pure, is a silver-white metal, so soft that it is like wax, and can be moulded in the fingers, or readily cut. It is a trifle lighter than water, and melts just below the boil- ing point of water. At a slightly higher tempera- ture, it burns with a brilliant yellow flame, which 195 196 THE METALLIC ELEMENTS is characteristic of all the sodium compounds. To keep it from tarnishing, it is ordinarily im- mersed in kerosene, or some other liquid free from water with which sodium will combine by decom- posing the water and freeing the hydrogen, while it forms two oxides, Na 2 O and Na 2 O 2 . When put into chlorine, sodium combines with it, forming sodium chloride, or common salt, and by this method Sir Humphry Davy proved the composition of salt. This compound, sodium chloride, NaCl, is found almost universally, being largely produced wher- ever sea water is evaporated, naturally or arti- ficially. The freezing of sea water excludes the salt from the ice, and the remaining thick solution of salt can be evaporated by heat. Natural de- posits of salt, known as " rock salt," are found in many countries, and in these the salt is mined or used impure for curing meat and preserving leather. Water will dissolve about one-third of its own weight of salt, or more, and when the water is allowed to evaporate, the salt crystallizes out in cubes. Common salt often contains chloride of magnesium, which attracts moisture, and in pre- paring table salt, this is removed. THE METALLIC ELEMENTS 197 Sodium hydroxide (NaOH) is used in the manu- facturing of soap, in paper pulp, and in many chemical industries. Its common name is caustic soda. Sodium peroxide (Na 2 O 2 ) contains one more atom of oxygen, and is used commercially APPAEATUS FOB THE MANUFACTURE OF SODIUM BY THE ELEC- TROLYSIS OF SODIUM HYDRONIDE The body of the steel cylinder rests within a heated flue. Hence the sodium hydronide is solid in the neck, and serves to protect the joint made by the iron cathode, C, and the crucible. A, A, is the iron anode. A collecting pot, P, dips into the molten caustic soda. As the electrolysis proceeds, the sodium formed at C collects in P, and a wire gauze, G, G, keeps it from mixing with the caustic soda. The sodium is ladled out at intervals from P. The hydrogen, which is liberated, accumulates, also in P, and prevents the sodium from oxidizing. for bleaching and oxidizing. There is also a sodium oxide. One of the most important com- 198 THE METALLIC ELEMENTS pounds of sodium is the sodium carbonate (Na 2 CO 3 ), which was formerly made by the burn- ing of seaweed, but is now prepared from the chlo- ride. The carbonate is often called soda, or sim- ply "alkali." It is the compound known as wash- ing-soda. It is used in making soap and in glass manufactures, and in preparing other sodium compounds. The bicarbonate of soda (HNaCO 3 ), the white powder commonly known as cooking soda, or bak- ing soda, is less soluble in water than the ordinary carbonate. When mixed with cream of tartar, the combination of the two sets free carbon dioxide, and this gas raises bread or cake dough by forcing its way into the paste. The name saleratus is some- times given to baking soda because of this property, since the word means the aerating salt. Seidlitz powders or Rochelle salts owe their effervescence to the same sort of combination, one of the powders used being soda bicarbonate. In medicine the same compound is often used for indigestion, to counter- act acidity. Sodium sulphate (Na 2 SO 4 ), a white solid, dis- solves readily in water, and crystallizes on evapora- tion into Glaubers salt, used in glass-making, in THE METALLIC ELEMENTS 199 dyeing, and also, when purified, as a medicine. Sodium nitrate is found in Chili, and is useful as a fertilizer and in the manufacture of nitric acid and potassium nitrate. It is known as Chili salt- peter, and is used in making blasting powder, but makes too explosive a compound for use as gun- powder. Borax is sodium borate, and occurs in the waters of certain lakes in Asia, from which it is obtained by evaporation. It is also found in California, in solution, and can also be extracted from compounds with calcium and manganese. It possesses valu- able antiseptic properties, is used as a food preserv- ative, and, owing to its property of dissolving many of the oxides, is used as a flux in blow-pipe analysis, as is mentioned below in speaking of boron. There are many other compounds of sodium, but these are the most important. POTASSIUM Potassium (K) is nearly as abundant as sodium, occurring as a compound in many plants, trees, and animal organisms. It is found as a nitrate in the soil of Ceylon and Bengal. Combined with silica, it occurs in feldspar and mica. Salts of potassium 200 THE METALLIC ELEMENTS are contained in all soils. Originally, potassium was extracted in the form of potash from ashes obtained by burning wood, leaves, and so on, these ashes being treated with water, and the solution evaporated, leaving what were known as potashes. It is now obtained by electrolysis from potassium hydroxide. It is a soft, white metal, much like sodium, slightly lighter, but ordinarily covered with a greyish coating, owing to the action of oxygen upon it. It melts far below the boiling point of water, and burns with a violet flame, which gives the test for its presence in compounds. Placed upon water, it takes fire, just as sodium does, and burns even more fiercely, giving a violet flame, forming the hydroxide, and releasing hydrogen. Its compounds closely resemble those of sodium, though it combines even more readily. The pure metal has no commercial uses, is expensive to pre- pare, and is only a chemical curiosity. An impor- tant compound is the potassium hydroxide, or caus- tic potash (KOH). It is employed in surgery as an active caustic to destroy the skin. It is an alkali of great strength, readily soluble in water, able to neutralize acids, and decomposes many metallic solutions. The nitrate of potassium is THE METALLIC ELEMENTS 201 saltpetre, or nitre, found in the soil of many warm countries. It is a white, soluble solid, with a salty, cooling taste, giving up oxygen readily, especially to charcoal and sulphur, which property renders it useful in making gunpowder, explosives, and in chemical compounds. Gunpowder often contains as much as seventy-five per cent, of saltpetre, which combines with the oxygen to form expanding gases that give the force to gunpowder explosion. Potassium chlorate is familiar as a remedy for sore throat. Its value consists in its readiness to part with oxygen, and it is likewise used in the preparation of fireworks. The carbonate of potas- sium is sometimes called potash, or, when purified, pearlash, and enters into the making of glass, soap, and other potassium compounds. Bromide of potassium is familiar in medicine, being used as a sedative, and also in photography as a means of slowing the action of developers. Potassium cyanide is often employed in extracting gold, particularly in Africa, and also is used with other cyanides in electroplating. Potassium sul- phate is useful as a fertilizer and in preparing alum. As a rule, the compounds of sodium are cheaper 202 THE METALLIC ELEMENTS than the similar compounds with potassium, and are therefore apt to replace them commercially wherever that is possible. Now and then the po- tassium compound will have certain qualities that fit it to a special use, and thus overcome its extra expense as compared with sodium. An advantage in the case of potassium is the fact that its com- pounds are often more energetic in combination. LITHIUM, RUBIDIUM AND CAESIUM The three remaining metals of this group are not only rare, but are of little use commercially. Lithium is the lightest of all the metal elements. Its compounds are widely distributed, but found in small quantities. Its action is like that of sodium toward water and oxygen, and it unites vigorously with hydrogen, nitrogen, and oxygen. Many of its compounds are almost insoluble, and in this respect lithium is more like magnesium than the alkali metals. The carbonate of lithium and some other compounds are supposed to be beneficial in certain rheumatic disorders. Lithium tends to give flame a bright red color. Kubidium and caBsium are two metals that were discovered by the use of the spec- troscope, and received their name from the color THE METALLIC ELEMENTS 203 of their characteristic lines, rubidium giving red, and caesium blue lines. They both form compounds much like those of potassium, and have somewhat similar properties. CALCIUM The pure metal calcium (Ca) belongs to a class known as " metals of the alkaline earths," being grouped with strontium and barium. While these metals are exceedingly rare, compounds of calcium are exceedingly plentiful, and the compounds of the others are useful and numerous. The metal, calcium, has to be preserved under naphtha, and is only a curiosity. Calcium, however, is found abundantly in marble, limestone, chalk, in shells, bones, coral, etc. The carbonate, or cal- cide, is the compound that forms these substances, and is found pure in the form of Iceland spar. Calcium sulphate is known as gypsum, alabaster, and selenite. Limestone is found abundantly all over the world, and differs greatly in hardness. Water containing carbon dioxide dissolves lime- stone, and as such water is very frequent in na- ture, there are innumerable formations depend- ing upon this property. The water frequently de- 204 THE METALLIC ELEMENTS posits the limestone again, forming the great stalac- tites and stalagmites. This accounts for the for- LIME KILN mation of the great Mammoth Cave in Kentucky, and the Luray Cave, in Virginia. From limestone are prepared limes and cements used in building. Forms of rock that owe their formation to shells are very numerous. Examples are the coquina of Florida, and the chalk cliffs of England. Lime- stone is exceedingly useful in the iron industry, From Stenograph, Copyright, by Underwood fa CO Oco I 1-1 00 Sff Ocfl 05 < _ be OS 05 ,5 Oi C3 ^^ S] ' r i ,*-. ^S 52 i i ^- S ,3 X i3 255 256 THE PEEIODIC SYSTEM valence II, and combines with two atoms of hydro- gen for each atom of its own. Carbon has the valency IV (or II), and thus combines with other elements accordingly. Many elements have more than one valency, as the table shows. Elements are named thus, according to valency, from the Greek numbers: I, Monad; II, Dyad; III, Triad; IV, Tetrad; V, Pentad; VI, Hexad; VII, Heptad; VIII, Octad. The adjectives are, monovalent, divalent, and so on to the end. In its first column the valence O appears. This means that the elements in that column Helium, Neon, Argon, Krypton, Xenon, rare gases in the air and elsewhere show no compounds. We may know the valence of any element in a compound by seeing how many of its atoms are found combined with those whose valence is known. Thus, in OsO 4 (osmic acid), since O has the valence II, and there are 4 O-atoms to 1 of osmium, we see that osmium must have the valence VIII, as the table gives it. The table shows how valence changes with atomic weight rises and falls, periodically. Thus, take the horizontal row beginning with Ne (neon) at THE PERIODIC SYSTEM 257 O valence, we have Na (sodium) I, Mg (magne- sium) II, aluminium III, silicon IV, phosphorus V (sometimes) or lower, sulphur VI (or lower), chlorine VII (or at times I). It is as if valence grew with weight, till it passed a certain point, and then increased or diminished according to the circumstances. This difference in valence corre- sponds with the different " equivalents " by which elements form compounds. Thus formula NH 4 C1 (ammonium chloride) shows nitrogen as a pentad, combining with an atom of monad chlorine and four atoms of monad hydrogen. Other formulas may be read in the same way. This relation in valency is only one of the resem- blances brought out by this " Periodic System." In general, the properties of the elements increase or decrease with the atomic weights. To perceive this a wide knowledge of chemistry would be neces- sary, but we may rest satisfied with the general notion that the table brings together the elements in like groups, and that the groups change regu- larly as we move up and down the columns, or across the rows, to and fro. Thus in the first column we find rare, inactive elements. In the second, beginning with lithium, 258 THE PERIODIC SYSTEM the lightest metal, we get heavier metals, with stronger metallic qualities, until we reach copper, silver, and gold. The third column also is increas- ingly metallic till we reach mercury, and below it (probably) comes radium which can be rightly put with mercury, the liquid metal, for it seems almost a gas-metal. Column fourth begins with carbon and silicon the two great foundations of organic and inorganic compounds and also leads to dense metals lead and thorium. Horizontally, from lithium, lightest metal, we proceed to the gas fluorine; from sodium to chlo- rine; from potassium to manganese in each case progressing regularly in power to combine with oxy- gen, or valence toward that element. In each row, the last four regularly lose valence toward hydro- gen (if they combine at all). Specific gravities" also will be found to be according to certain orders in the table. But for its many striking features, chemical treatises must be consulted. We will only pause to say that since the table was first made, it has led to the discovery of at least three new elements to fill spaces that were blanks (scandium, 1879, gal- lium in 1875, and germanium, 1888). These Men- THE PERIODIC SYSTEM 259 dele"ef predicted with others not yet found. The table also helps to fix doubtful atomic weights, and suggests lines of work to chemists, while it helps to classify the elements, and to confirm discoveries and researches. CHAPTER XVI THE STORY OF CHEMISTRY IN very truth the story of chemistry might begin with man's use of fire, or with the earliest use of metals, and we have already seen that speculation about what substances were made of began far back even of the alchemists. But in a true sense, if we wish to know about the modern science of chemis- try we can hardly go further back than the English philosopher, Eobert Boyle. Before his century, even, hundreds of compounds were made in the East and in Europe, and there are names of great experimenters such as Albertus Magnus, Roger Bacon, Raymond Lulli, and Para- celsus, who were wise for their time, and held views more or less correct about chemical questions. But with Robert Boyle we first have the idea of widely applicable^laws and theories, as against the fanci- ful superstitions of the alchemists. Boyle was against all such wild notions, and wrote a book pointing out the absurd claims and ridiculously stilted language of the chemists of his time. 261 262 THE STOKY OF CHEMISTRY Boyle belonged to a society known as the " Invisi- ble College," a body of men interested in science and the arts, that afterward gave rise to the Royal Society. Boyle championed the view that all mat- ter was made up of smaller particles or bodies, and urged the need of making true experiments, and of setting forth results in plain language all men might understand. With him true analysis of sub- stances began. To him we owe that great princi- ple, " Boyle's Law," discovered by him in 1660 at an unchanged temperature any gas occupies less volume as the pressure is greater that is, double the pressure and the volume is halved ; or halve the pressure and the volume is doubled. This has become the very foundation stone of modern ideas about how matter is made up, for on it is based the theory of atoms, and all that has fol- lowed. Next to Boyle should be mentioned Priestley, con- cerning whom it is interesting to know that it was Benjamin Franklin's gift of some books on elec- tricity that formed the turning point in Priestley's life, leading him toward science. Though Priestley believed some of the mistaken notions of his day, yet to him, with the great Lavoisier, is due the honor of THE STORY OF CHEMISTRY 263 discovering the composition of air and the element oxygen. Priestley, by means of a burning-glass lens heated "the calx of mercury" (mercury oxide) and found that "air" was given off under a bell-glass. This "air " when tested was seen to be something unknown, and its study was the dis- covery of oxygen. Priestley also invented the " pneumatic trough " for collecting gases. He sep- arated ammonia into its gases hydrogen and ni- trogen, and made studies upon the nature of com- bustion which in his day was believed to consist in the driving out of an imagined substance called "phlogiston." Priestley himself shared this the- ory. When it was shown that a burned substance sometimes gained in weight (by absorbing oxygen, of course), the believers in phlogiston were forced to argue that it might be a substance of " negative gravity." Oxygen was first called " dephlogisti- cated air " and nitrogen " phlogisticated air " from this theory. The next English chemists of note were Black, an opponent of phlogiston, who discovered " carbonic acid gas " (CO 2 ) and proved its relations to certain carbonates of alkalies and alkaline earths; and Henry Cavendish, the strange, interesting recluse 264 THE STOEY OF CHEMISTRY who showed the composition of air, that of water, and who studied deeply into the nature of heat. To him is due the discovery of hydrogen and its unit- ing with oxygen to form water when burned; and much study of the weight of gases. He showed how the calcium carbonate was dissolved by water containing carbon dioxide, and analyzed nitric oxide. Many amusing anecdotes are told of his eccentricities and his shyness. Then the great names become frequent, for the true path to chemical knowledge was becoming known. Of Dalton we have told already, and we will only remind the reader of his atomic theory and of the law of multiple proportions, which certainly were first clearly put forth under his name. The law of definite proportions was at this time much disputed. The great champions were Ber- thollet and Proust the former urging that ele- ments combined in many unfixed amounts, and that solutions in all degrees might be regarded as com- pounds. It was early in the nineteenth century that Proust's party succeeded in showing that mix- tures were not compounds, and Berthollet's party were compelled to admit the law. During this con- Itcprodueed from " Young'* Elementary Principles of Chemistry," Inj permixRinn of D. Appletoii ,E- Company JOSEPH Louis GAY-LUSSAC B. France, 1778. D. Paris, 1850. THE STORY OF CHEMISTRY 265 troversy much information was acquired by the dis- putants, and Dr. Wollaston, famous in electric science, pointed out that elements combined in multiple proportions which completed the rule, " elements combine in definite and multiple propor- tions " as we have seen. The same period saw from the French chemist, Gay-Lussac, a publication pointing out the laws of the combination of gases that these combine in definite proportions if under the same heat and pressure, and form fixed volumes which led to the theory announced by Avogadro concerning the rea- son for the result. The idea that each gas con- tained compound atoms (molecules) in equal num- ber proved a most fruitful one; and the word " molecule " took its place in the science but only in after years was the discovery accepted, together with the atomic theory in completer form. The proving of the theory is credited to Ber- zelius, a Swedish chemist, and Thomson, a Scotch professor. Berzelius was a great analyst, and tested the theory in his laboratory, making experi- ments to confirm the combining of elements in fixed proportions. To him is due the system of letters and numbers that enable us to write chemical for- 266 THE STORY OF CHEMISTRY mulas. This way of writing the results of ex- periments made the theory evident and widely known. Next came Dulong and Petit's experiments, show- ing that the elements had "specific heat" accord- ing to their atomic weights, and the discovery by a German chemist that " elements having the same number of atoms to the molecule are disposed to form the same angles of crystallization." This is known as "isomorphism," from isos, like, and morphos, form. Dr. Henry Smith Williams in his article, " The Century's Progress in Chemistry " (Harper's Maga- zine), sets forth these facts much more fully, and shows how the atomic theory gradually became an indisputable part of chemistry and the forerunner of the modern science. I have not met with a bet- ter brief history of the science and have been greatly aided by his article in this chapter. With Sir Humphry Davy the union of the sciences of chemistry and electricity began, and almost at once enabled him to make brilliant dis- coveries. He first separated potassium and sodium as metals from their compounds, and soon in the same way discovered calcium, barium, and stron- THE STORY OF CHEMISTRY 267 tium. On decomposing water, various substances besides hydrogen and oxygen were set free at the poles, but Davy was able to prove that these were impurities derived from the apparatus. Meanwhile a theory had grown up that all com- pounds were built up of " binary " combinations of " positive " and " negative " atoms ; and this was championed by Berzelius with much ability. It had many facts in its favor, such, for example, as the persistence of the " radicals," of which Gay- Lussac in 1815 had discovered cyanogen (CN) and Ampere had, a year later, discovered ammonium (NH) ; and for years it was widely accepted. But later investigations, and increase of skill in the putting together of compounds were to show there was no such general law. Its overthrow came soon after Wbhler's achievement in making the or- ganic compound, urea. This opened the way to the conquest of organic chemistry, and brought about the study of carbon and its compounds that led Liebig to his triumphs in agricultural chemis- try the study of the enrichment of soils and the improvement of food-stuffs; and also saw the entry upon the same field of the French chemists, Dumas and Pasteur. 268 THE STOEY OF CHEMISTRY The studies in organic chemistry revealed many radicals and many of them were binary com- pounds. But Dumas was able to substitute oxy- gen, a " positive " element, for the " negative " element chlorine, and thus to show that the binary theory of Berzelius was not a law. This led to further investigation and speculation in regard to the make-up of molecules, and brought about the proof that certain molecules must contain more than one atom of the same element. As pre- viously shown, if hydrogen unites with oxygen, making one volume of oxygen -}- two volumes of hydrogen = two volumes of water-vapor, then the molecules of oxygen must have split into two atoms. If so, the oxygen molecule is O 2 . Similar reasoning with other elements and com- pounds brought out the theory of " valency," and of the exchange of atoms in the forming of com- pounds. This was a great gain for several reasons. It explained that there was a limit to the com- binations of certain elements with one another. Knowing that the valencies of H, O, N, and C were I, II, III, IV, respectively, it was evident that H and O, for example, could only combine thus, H O , H O H, H O O H, and that all Ktn>mliif,i-,l from " Youny's Elementary Principles of Chemistry," by permission of I). Appleton & Company. JOSEPH BLACK B. Bordeaux, 1728. D. Edinburgh, 1799. THE STORY OF CHEMISTRY 269 these had used their valencies except the first H O , which was less stable than the others, or could not stand alone. It also showed what was meant by the " isomerism " discovered by Liebig and Wohler the existing of differing compounds that yet were made up of the same number and the same kind of atoms. And this led to the close study of how atoms were grouped as shown by graphic formulas such as we saw in the chapter on carbon com- pounds, and also of their action in entering or leaving these groups. Out of these studies have come the ideas of " disassociation " the tendency of atoms to leave one combination and enter an- other, and the " reversibility " of chemical combi- nation or the tendency in many cases of a chem- ical action to swing back again to its first condi- tion if the elements, molecules, or atoms are not separated or set free in some way at some stage of their movements. All these views tend to increase the complexity of chemical study, and at the same time to make actions and reactions better understood, and more capable of control. The subject became deeply specialized, and the mass of facts accumulated was so enormous that chemists longed for some simpli- 270 THE STORY OF CHEMISTRY fying for general laws that would make the knowl- edge systematic. The earliest steps toward this desired end were in an attempt to show that there were not so many elements that possibly some of them were com- pounds, and that study might prove there were but few real "elements." It was even suggested by Prout, in 1815, that, since many of the atomic weights were multiples of the atomic weight of hydrogen, it might be all elements were but forms or compounds of this single one. In 1840, Dumas made some attempts toward a possible proof of this theory, but it would not lend itself to proof. Help came in another way. In 1864 the chemist, John Newlands, showed that if the elements were put in the order of their atomic weights, there seemed to be a law of " octaves," and this led to the studies of the American, Hinrichs, the German, Meyer, and the Russian, Mendeleef with the re- sult already explained in discussing the Periodic System. Another help was found in the spectroscope. By the aid of this instrument, and of photography, it was possible to examine and compare the spectra of bodies, not only on earth, but in the heavens. THE STORY OP CHEMISTRY 271 Its revelations of the gradual simplifying of ele- ments present, as hotter and hotter stars are exam- ined there being only one-half of our list in the sun, and still fewer in Sirius was taken as an encouragement to the belief that elements here un- changeable might under other circumstances be shown to be compounds. We cannot discuss every important step made in more recent years, as again the great mass of mate- rial forbids. But since the discovery of the Ront- gen rays the x-rays, in 1905, there has been a most startling advance in the study of matter. Fol- lowing Rontgen came the French chemist, Bec- querel, with the discovery of " rays " from uranium, and the German, Schmidt, who found rays from thorium. Then, at BecquereFs instance, M. and Mme. Curie made a thorough examination of the elements, and found no " rays " except in these two uranium and thorium. But rays were abundant in certain minerals especially pitchblende, where- from came rays even stronger than those from ura- nium. Patient, heroic work began. A car-load of pitchblende was laboriously analyzed, and out of it was secured one-quarter of a grain of chloride of 272 THE STORY OF CHEMISTRY " radium " a new element. This was the %ooooooth part of the pitchblende, and the quarter grain had been evenly diffused throughout! Its cost was at the rate of $25,000,000 a kilogram. Then began the study of the new element, and of its three kinds of rays known as a, y? , and 7- alpha, beta, and gamma rays. This study was ex- haustive, accurate, and complete. It has been veri- fied by observers throughout the world, and leads to most amazing conclusions. When certain of these rays or emanations are collected in a glass tube, and subjected to examination, it has been found that there is no trace of radium, but that in the tube is a gas the gas of the element helium, as the spectrum of it proves. Again we must condense. Let us say in brief that here are some of the chemists' conclusions: In pitchblende, where uranium is found, is found also a proportionate amount of radium. From the uranium, it is believed, may come the radium. Then the " rays " from radium change into helium. From helium there is a further change to polonium, another new element. Thus the chain already formed seems to show an element (uranium) giv- ing rise to three others, and it is thought also Reproduced from " Young's Elementary Principles of Chemistry," by permission of D. App'eton ,t- Company. CLAUDE Louis BERTIIOLLET B. Savoy, 1748. D. Paris, 1822. THE STORY OF CHEMISTRY 273 that when the uranium shall have ceased to send forth its emanations, that which is left of it will be another element this time a familiar one the heavy, inert, metallic element, lead. Such is the most recent evidence that there is hope that the elements may be simplified in number. It is impossible not to recall the gradual steps by which, beginning with the masses of matter them- selves, men have come to believe these made up of molecules, have then been forced to seek further for the atoms that compose molecules ; and are now finding in the atoms so much else. We have been forced to see electrons in the radio- active bodies, ions and kations in solutions, and to-day speculation is busy in trying to get within the orbits of electrons, hoping to know whether there is a central nucleus of matter or nothing whatever ! 274 TABLES AND NOTES 355 E-Ss 3 13*1 g fisgg * g 9 s ffSlijfcaJrtSJ 1 la Sgg ii?I OO J^ *5 lilallslxlj Illl * os I o o'^o od t> o o o I I o io>ao o o O O W> O5 S<5 OS t- * 1-1 * CO SO 10 i-c 00 !O t- ** rt I- -H ( -^c ^- -5. ( 10 O O r-l >f) t~ t~ O> ^- O< OS O 00 S<5 O u, 03X5 ffi E ,5 _< fa :S o !| :IJ i si :c C '.B I :'ES l|e|ii^^iiijil|^|||llM i HsiS^Il I TABLES AND NOTES 275 sgssssisiggs 276 TABLES AND NOTES F. 3500 - 6330 3000 5400 2800 5072 2500 4532 2225 4037 2231- 4000 1710 3080 1530 2731 1400 - 2552 1371 2500 1200 2192 1100- 2012 1063 1981 1050- 1922 970- 1778 700- 1292 625 1157 405- 762 400- - 752 357- 674 316 - 600 288- 550 215 420 109 228 100 - 212 79- - 174 65 149 61- - 142 46 114 44- Ill 40- - 104 37.7 100 36.8- - 98 35 - 951 30- - 86 25- 77 20 - 68 17- - 62 15 - 59 10- 50 5- - 41 32 -10- - 14 -17.7- -20- - -4 -38.8- - 34.3 -40- - -40 -55 68 -70 -94 -100- - -148 -191 - -312 -252- 422 -257- - -432 -260- 436 -278- A 459 L THERMOMETER Temp, of electric arc. Carbon vaporizes. Temp, attained by Thermit. Oxy-Hydrogen flame. Osmium melts. Iridium melts. Heat in Bessemer Furnace. Platinum melts. Wrought iron melts. White heat. Steel melts. Orange-red heat. Copper melts. Pure gold melts. Cast iron (lowest) melts. Silver melts. Dull red heat. Aluminium melts. (about) Coal ignites. Red-hot iron visible in dark. Mercury boils. Lead melts. Gunpowder ignites. Tin melts. Sulphur melts. Water boils. Alcohol boils. Fusible Alloy melts. Beeswax melts. Paraffin melts. Phosphorus melts. Human body in health. Mean temp, of sea. Mean temp, of air (London). Water freezes. Mixture salt and ice. Mercury freezes. *Greatest natural cold on earth (antarctic). Sounding balloon (9 miles high). Air liquefies under normal pressure. Hydrogen liquefies. Hydrogen freezes. Greatest artificial cold pro- duced (Dewar). Absolute zero. TABLES AND NOTES 277 ELEMENTS IN CRUST OF EARTH WATER By combining a large number of analyses of rocks of all sorts, F. W. Clarke has estimated the relative amounts of elements in the crust of the earth: Oxygen ...... 47.02 per cent. Manganese ... .07 per cent. Silicon ...... 28.06 " Sulphur ...... 07 " Aluminium . . 8.16 " Barium ....... 05 " Iron ......... 4.64 " Strontium ... .02 Calcium ...... 3.50 " Chromium ... .01 " Magnesium ... 2.65 " Nickel ........ 01 " Sodium ...... 2.63 " Lithium ....... 01 " Potassium ____ 2.32 " ^ Chlorine ...... 01 " Titanium .... .41 " ML Fluorine ...... 01 " Hydrogen _____ .17 " Carbon ....... 12 " 100 Phosphorus . . .09 " Science Tear Book, 1908. Mean density of the whole earth is 5.53 times that of water. Science Tear Book, 1908. * Capt. Amundsen reported (in 1905) a temperature of 61.7 C (or 79 F) in Boothia (N. Canada). 68 C is said to have been experienced in Siberia. Fahrenheit derived his scale from putting zero as the greatest cold then ascertained ( by mixing salt and ice ) . The temperature of the human body was the other standard, and the space be- tween these points was divided first duodecimally into 24 and later into one quarter of this, or 96. Reaumur's scale (used in Germany) divides the space between the freezing and boiling points of water into 80. To convert these scales F = C + 32 = R + 32 R0 ^ 278 TABLES AND NOTES THE AIR 1 cubic foot of air at 62 F. weighs .076 Ibs. (= 1.217 ozs. or 532.7 grains) ; at 32 F., .08 Ibs. 1 litre at 32 F. weighs 1293 grammes. 13.141 cubic feet at 62 F. weigh 1 Ib. Normal atmospheric pressure 14.7 Ibs. per sq. inch = 2116.4 Ibs. per sq. foot. A column of mercury 30 inches high or a column of water 33.947 ft. is supported. Sir F. Abel and Sir A. Noble obtained (in researches with explosives) pressures in closed steel cylinders up to 95 tons to the square inch. Air expands, or contracts, .002 of its volume per F. Air, under normal pressure, liquefies at 191 C. At 39 atmosphere pressures it will liquefy at 140 C. Liquid air occupies % 00 th the volume of air. The average composition of normal air may be taken as fol- lows : Vola. Nitrogen 769.5000 Oxygen 206.5940 Aqueous vapour 14.0000 Argon 9.3700 Carbon dioxide 0.3360 Hydrogen 0.1900 Ammonia 0.0080 Ozone 0.0015 Nitric acid . 0.0005 1,000.0000 Also- Neon 0.000014 Helium 0.00000276 Krypton a trace Xenon . a trace TABLES AND NOTES SIZE OF MOLECULES 279 The diameters of Molecules have been ascertained by Jeans to be Hydrogen 20.3 Nitrogen 29.1 Oxygen 27.3 These figures express number of billionths of a metre. METALLIC SALTS These are formed when metals replace the hydrogen of acids; or when acid-forming oxides combine with basic oxides; or when metals exchange with hydrogen in combining an acid and a hydroxide. If all the hydrogen is replaced, " normal salts " are formed ; if part is left, an "acid salt." Basic salts result from the combining of a normal salt with a basic oxide or hydroxide. CONDUCTIVITY OF METALS Substance. Heat Cond. Electrical Cond. Silver 100.0 100 Copper 73 6 73 3 Gold 63 2 58 5 Aluminium . . 31 3 BO 5 Brass 23 6 91 ^ Zinc 19 9 QQ o Tin 14 5 99 R Iron 11 9 1Q ft Lead . . . 8 5 10 7 Platinum 6 4 10 ^ Bismuth 1 8 1 Q Mercury 1 R 280 TABLES AND NOTES WATER Composition: 2 vols. Hydrogen to 1 Oxygen. Maximum density at 4 C. (below which it expands slightly). Water converted to steam expands to 1700 times its volume. Water is 819.4 times as heavy as air. Composition of rain water (London) : Organic Carbon... .99 part in 1,000,000 water. Organic Nitrogen. .22 " " " Ammonia 50 " " '* " Nitrates and Nitrites .07 " " " " Chlorine 6.30 " Total Solids 39.50 " " " " COMMON NAMES OF CHEMICALS Common Names. Chemical Names and Formulae. Alum Sulphate of Aluminium and Potassium Aqua Fortis Nitric Acid, HNO 3 Aqua Regia Nitro-Hydrochloric Acid Calomel Mercurous Chloride, Hg 2 C1 2 Carbolic Acid Phenol C 6 H 5 OH Caustic Potash Potassium Hydrate KOH Caustic Soda Sodium Hydrate, NaOH Chalk Calcium Carbonate, CaC0 8 Copperas Sulphate of Iron Corrosive Sublimate Mercuric Chloride, HgCl 2 Cream of Tartar Potassium Bitartrate Epsom Salts Magnesium Sulphate Ether Diethyl Oxide (C 2 H 5 ) 2 Fire Damp Light Carburetted Hydrogen Galena Lead Sulphide, PbS Glauber's Salt Sodium Sulphate Glucose or Grape Sugar Dextrose C 6 H 12 O 6 Goulard Water Basic Acetate of Lead Iron Pyrites Iron Di-Sulphide, FeS 2 Jewellers' Putty Oxide of Tin Laughing Gas Nitrous Oxide, NO TABLES AND NOTES 281 COMMON NAMES OF CHEMICALS Continued Lime Calcium Oxide, CaO Lunar Caustic Silver Nitrate, AgN0 8 Mosaic Gold Bi-Sulphide of Tin Muriatic Acid Hydrochloric Acid, HC1 Olefiant Gas Ethylene, C 2 H 4 Plaster of Paris Calcium Sulphate Quartz Silicon Dioxide, Si O 2 Realgar Arsenic Di-Sulphide, As S. Red Lead Oxide of Lead, Pb g O 4 Rochelle Salt Sodium Potassium Tartrate Salammoniac Ammonium Chloride Salt, Common Sodium Chloride NaCl Salt of Tartar Potassium Carbonate Saltpetre Potassium Nitrate, KNO 8 Salts of Lemon Oxalic Acid Slaked Lime Calcium Hydrate Soda Sodium Carbonate Spelter Zinc Spirits of Hartshorn Amm. Hydroxide, N 4 H.OH Spirits of Salt Hydrochloric Acid, HC1 Sugar of Lead Lead Acetate Tartar Emetic Potass. Antimony Tartrate Verdigris Basic Copper Acetate Vermilion Sulphide of Mercury Vinegar Dilute Acetic Acid Vitriol, Blue Copper Sulphate " Green Ferrous Sulphate " Oil of Sulphuric Acid, H 2 SO 4 White Zinc Sulphate Volatile Alkali Ammonia 282 TABLES AND NOTES FREEZING MIXTURES Ingredients. f Snow or pounded ice Chloride of sodium (salt) Water Saltpetre Chloride of ammonium ammoniac) ( sal [Water Nitrate of ammonia. fWater 4 J Nitrate of ammonia Carbonate of soda (Snow Crystallized chloride of cal cium [Crystallized sulphate of soda. 1 Hydrochloric acid (Solid Carbonic Acid dissolved in Sulphuric ether 16 5 20C. 26 45 50 146 EXPLOSIVES GUNPOWDEE (English) Saltpetre 75 parts. Charcoal 15 " Sulphur 10 " Ground to fine powder and intimately mixed: then granulated. 1 c. in. on exploding expands to 800 c. in. of gas. TABLES AND NOTES 283 GUNCOTTON Cotton immersed in three parts sulphuric acid (sp. gr. 1.84) and 1 part nitric acid (sp. gr. 1:52) and thor- oughly washed; 2 to 4 times as powerful as gunpowder. NITRO-GLYCERINE (C g H g N g O lg ), sp. gr. 1.6 Nitric acid 1 parts by wt. Sulphuric acid... 2 Glycerine being injected into the mixture, nitro-glycerine floats to the top, is drawn off, washed, and filtered. Explodes at 240 to 300 F., 1 c. in. expanding to 10,000 c. in. of gases, or about 10 to 13 times as strong as gunpowder. DYNAMITE 3 parts by wt. nitro-glycerine, mixed with 1 part Kieselguhr. (infusorial earth). BLASTING GELATINE Guncotton dissolved in nitro-glycerine. COEDITE Practically the same. PICBIC ACID (Lyddite, Melinite, etc.) Carbolic acid treated with nitric acid. CHEMICAL NOMENCLATURE. TERMINATION " UM" is now applied to all METALS, though the older-known metals retain the former names, e. g. Aluminium, Tellurium, etc. TERMINATION " IDE " denotes a BINARY COMPOUND, that is, a substance composed of only two elements, e. g. Sodium Chlo- ride (NaCl). TERMINATION " OUS " is applied to the first of two elements when it exists in a greater proportion than in another com- bination with the same element, e. g. one atom of phosphorus and three atoms of chlorine form PHOSPHOROUS CHLORIDE. TERMINATION " 1C," when the first exists in a lesser pro- portion, e. gr. -one atom of phosphorous with five atoms of chlorine form PHOSPHORIC CHLORIDE. PREFIXES "MONO," " BI ," "TRI ," Ac., indicate the proportion of the latter of two elements, and are sometimes used instead of the above termination. Thus phosphorus chloride may also be called PHOSPHORUS TRI-CHLOBIDE ; so one atom of carbon with one atom of oxygen is CARBON MONOXIDE. PREFIX "HYPO" (under) and "PER" (over), specify compounds formed by the same two elements containing less (or more) of an element than is in the usual compound. SESQUI means in the proportion of 1 to 1^ or 2 to 3. 284 TABLES AND NOTES ALLOYS Bell Metal = 4 copper, 1 tin. Brass = 1 zinc, 2 copper. Bronze (coins) = 95 copper, 4 tin, 1 zinc. German Silver = 3 copper, 1 nickel, 2 zinc. Gold (coinage = 22 carats)*. = 11 gold, 1 copper. Gold ( Jeweller s'=; 18 carats).. = 3 gold, 1 copper. Gun Metal = 9 copper, 1 tin. Invar = 2 steel, 1 nickel. Magnetic Alloy = 60 copper, 26 manganese, 14 aluminium. Pewter = 4 tin, 1 lead. Silver (coinage) = 37 silver, 3 copper. Solder (soft) = lead and tin (varies) . Solder (hard) = copper and zinc (varies) . Speculum Metal = 126.4 copper, 58.4 tin. Type Metal = 4 lead, 1 antimony, and tin (var.) WOOD'S FUSIBLE ALLOY Bismuth, 4 parts. Lead, 2 parts Tin, 1 part. Cadmium, 1 part. Melts at 149 F. METALLIC OXIDES MONOXIDE i= replacing of each atom of hydrogen in H 2 by a monad, or both by a dyad. HIGHER OXIDES = replacing of hydrogen atoms in molecules of water by equivalent atoms of metals. HYDEOXIDES = only a part of hydrogen is replaced in the water molecules. In solutions with water these have alkaline reaction. BASIC OXIDES and HYDEOXIDES form salts with acids, the metal replacing hydrogen. PEROXIDES, and ACID-FORMING Oxides, have more oxygen than basic oxides. * Pure gold has 24 carats ( of 240 grains ) in a Ib. INDEX Abel, Sir F., researches of, with explosives, 278 Acetates (see also Organic Acids), 223; uses of, 223; lead, 235, 280, 281 Acids (see also Organic Acids), 222; essential ele- ments in, 97; nature and qualities of, 97; elements contained by, 97; result of action of, upon a base, 98 ; nature of, 99; action of weak and strong, 99; com- moner, 99 ; examples of, in foods, 100; taste of, 100; chemical definition of, 100; hydrogen chief element in defining of, 101 ; oxygen contained by most, 101 ; "trade names" of, (refer tables) , 102 ; ordinary names of, 101-102 ; result of combination of, with a base, 104; terminology re- lating class of, with specific salts, 105; compounds of non-metals produce, 130 ; neutralized by ammonia (see Ammonia), 188 Acetic Acid, 100; ( see < also Organic Acids), 223; foot- note, 223; dilute (see Vine- gar), 281 Air, 9-15 ; animals' and plants' need of, 16 ; how to secure perfectly dry and pure, 19; composition of, 37; compo- sition of, discovered, 263; composition of discovered (see Cavendish), 264; de- gree of liquefaction of, un- der normal pressure, 276; mean temperature of (in London), 276; (see Table of Elements), 278; weight of, 278; expansion of, 278; contraction of, 278; lique- faction of, 278; relative volume occupied by liquid, 278 ; average composition of normal, 278; volumes respectively of : Ammonia, Argon, Carbon dioxide, Helium, Hydrogen, Kryp- ton, Neon, Nitric acid, Nitrogen, Oxygen, Ozone ; in normal, 278 Alabaster, 125 ; (see also Calcium sulphate), 203 Albertus Magnus, 281 Albumen, 40; (see also Car- bon compounds), 225 Alchemysts, origin of be- liefs of, 5 ; testimony con- cerning success of, results of experiments of, men- tion of history of, traces of beliefs of in chemical words, metals related to planets, in beliefs of, 7; mention of, 261 Alchemy, origin of word, to what applied, 6 Alcohols, 220-222; meaning of word, 221 ; difference be- tween ether and, 222; boil- ing point of, 276 Aldehydes (see Carbon com- pounds), 221; formula for acetic (footnote), 223 Alkalies (see Sodium Car- bonate), 197; true balance 285 286 INDEX of with acids, in relation to health, 10 ; defined, tested, 10,5 ; caustic (see Ammonia), 188; caustic potash an (see Potassium hydroxide), 200; chloral decomposed by (see Chloro- form), 221 Alkaline properties, elements possessing, 195 Allotropism defined, 92 Alloys, 131-132 ; table of, 284 ; melting point of fusible, 276 ; uses of silver, 139 ; see also: aluminium, 199, 284; antimony, 166, 284; bis- muth, 184; copper, 140-141, 284; gold, 284; lead, 168, 284 ; manganese, 284 ; man- ganese bronze, 181 ; nickel, 284; silver, 284; steel, 284; tin, 284; zinc, 2&4; Wood's fusible, 284; proportions of Bismuth in, proportions of Cadmium in, proportions of lead in, proportions of tin in, 284 Alum, 179, 280; uses of, 179 Aluminium first obtained, comparative supply of in earth's crust, minerals in which is found, 175; orig- inal costliness of, history of extraction of, 175-6-7; production of, by electro- lysis, 177; properties, quali- ties and uses of, 177-8; pre- cious gems mainly, 178; temperature of fusion of, 179; glucinum found with, 185; melting point of, 276; see also: table of Valences in Periodic System, 255-7; Table of Elements, 274; Table of Alloys (Magnetic Alloy), 284; and: alumin- ium bronze, qualities of, 179; aluminium filings, hy- drogen procured by use of, 179-180 ; aluminium sili- cate, pottery clay consists of, 179; aluminium sul- phate, 179 Alumino-Thermics, 180 Amalgams, 131 ; Mercury, 171 Amethyst (see Crystalline silica), 208 Ammonia (see Volatile al- kali), 281; as a base, com- bination of elements in, 103; acids neutralized by, 103; preparation of, 186; properties, qualities and uses of, 187-8-9; volume of, in normal air, 278; propor- tions of, in rain water, 280 ; hydroxide, 187; (see also Nitrogen compounds of), 186-9 inch; Nitrate of (see Freezing mixtures), 282; (see also Priestley's exper- iments), 263 Ammonium Chloride, 257 ; (see also Salammoniac), 281 ; Ammomium group,188 ; Ammonium Hydrate, uses of, 189; Ammonium Hydro- oxide (formula), 281; (also Spirits of Hartshorn), 281; Ammonium Sulphate, 188-9 AmpSre, 274; ammonium dis- covered by, 267 Amundsen, Captain, 277 Amylenes, 224 Anesthetic, ether used as, 222 Anilines (see Carbon com- pounds), 224 Aniline Dyes, 40 Anions, as non-metals (see Experiments in Electro- lysis), 236 Anode (see Faraday's exper- iments in electrolysis), 235- 36 Anthracite (see Coal), 90 Antimony, group of elements includes, 108; effect of Arsenic combined with, in chlorine, 112; uses of, 166; uses of compared with bismuth, 184; uses of in INDEX 287 commerce, 167 ; description of, symbol for, thermopyle formed by bismuth and, 166 ; proportions of in type- metal, 284; (see also Table of Elements), 274 Aqua Fortis (see Nitric acid), 191-280 Aqua Regia, 134-280 Arfordson, 274 Argon, 21, 256, 274 Arsenic, group of elements includes, 108; effect of an- timony combined with in chlorine, 112 ; atomic weight of changed, 127j descrip- tion of, uses of, "symbol of, 165; dangers of, symptoms of poisoning by, 166; in Table of Chemical Ele- ments, 274 Arsenic Di-Sulphide, formula (see Realgar), 281 Asia, Sodium borate found in, 199 Astronomy, why scientific earlier than chemistry, 8 Atmosphere, elements com- posing our, in order of their weights, 20 Atom, definition of, 53 Atomic Theory, what made possible by, 57; (see Boyle's Law), 262; (see Dalton's Law), 264; acceptance of, in completer form, 265 Atoms, molecules made up of, 64; weight of, 72-4-5; ex- change of in compounds, 268; relation of, to com- position of matter, 273 Atomic Weights, table of, changed, 127 ; standard for finding, of elements, 245; Laws of, 251-2 ; ( see Law of Dulong and Petit), 251; relation between specific heat and, 252; (see Exper- iments of Dulong and Petit) Avogadro, Amadeo, theory of concerning gases, 248-9, 265 Avogadro's Law, explanation of, 249 Azote, 35 Azotized, 35 Bacon, Roger, 261 Baking Soda (see Bicarbon- ate of soda), 198 Balard (see Bromines), Table of Chemical Elements, 274 Balloons, process of prepar- ing hydrogen for (see alu- minium), 180 Bamboo, silica for coating, 209 Barium, 184-5 ; use of, in manufacture of paints, use of salts of, 185; calcium grouped with, 203; discov- ered, 266; (see also Table of Chemical Elements), 274 ; (see also Table of Ele- ments of Earth's Crust), 277 Bases, definition of, elements contained in, character of, 97; result of action of, upon acids, 98, 104; word, how used in chemistry, 103 ; examples of acids neutralizing, definition of substance of, term for dis- tinguishing, 103 ; metals combine with oxygen and hydrogen to form, 130 Basic Salts, 279 Beams, preparation of steel for building, for bridge, 154 Becquerel, rays from uranium discovered by, 271 Beeswax, melting point of, 276 Bell Glass (see Priestley's Experiments), 263 Bengal, potassium found in, 199 288 INDEX Benzol (see Coal-tar), 226 Berthollet (see Law of Defin- ite Proportions), 264 Beryllium (see Glucinium), 185; and Table of Ele- ments, 274 Berzelius, selenium discov- ered by, 126; (see Theories of combination of gases), 265-8; (see Theory of bin- ary combinations), 267-8; (see also Table of Chemi- cal Elements), 274-5 Bessemer (see Steel), 152 Bessemer Furnace, heat in, 276 Bessemer Process, 152 Bi (prefix) in chemical no- menclature, 283 Bicarbonate of Soda, 198 Binary Combinations, theory of, 267-8 Binary Compounds, termina- tion denoting, 283 Bismuth, color of, 130; de- scription of, comparative weight of, uses of, in medi- cine, 184; (see also Table of Chemical Elements), 274; (see also Table of Conductivity of Metals), 279 Black, Carbonic acid gas dis- covered by, 263 Black Phosphorus, prepara- tion of, 192 Blast Furnace, diagram of, 147 Blasting Powder, Chili salt- petre used in, 199 Blue Vitriol (see also Copper Sulphate), 141 Boisbandran (see Atomic wts. of Gallium and Samarium), 274-5 Borax (see Sodium borate), 199; description of, for- mula for, laboratory uses of, general uses of, oxides dissolved by, 207; (see also sodium salt), 207 Boric Acid, where occurring, 207 Boron, carbide of (footnote), 89; weight of, changed, 127; description of, 206; silver classed with, 208; (see also Table of Chemi- cal Elements), 274 Boyle, demonstration of, con- cerning gases, 248; relation to modern chemistry of, 259; true analysis of sub- stances begins with, 262 Boyle's Law, 262 Brandt (see Phosphorus and Cobalt, Table of Chemical Elements), 274-5 Brass, Table of Conductivity of Metals, 279 Bridge Beams, preparation of steel for, 154; (see Iron and Steel, processes of manufacture of) Bromide, of potassium, 112- 113, 201; use of, in medi- cine, 113-201 ; use of, in photography, 201 ; of silver, use of, 113; (see also Sil- ver), 138 Bromine, group of Halogens includes, 108 ; atomic weight of, two ways of preparing, chlorine combined with, sodium combined with, 112 ; action of, description of, effect of, uses of, deriva- tion of name, discovered, 113; (see also Table of Elements), 274 Bronze Age, 139-144 Bronze (see Copper), 139- 142 ; aluminium (see alu- minium), 179; bronze man- ganese (see manganese), 181; bronze alloy (coins), Table of Alloys, 284 Building, beams (see pro- cesses of steel manufac- ture), 154; cements (see limestone), 204; limes, 204 Bunsen (see Caesium and INDEX 289 Rubidium, Table of Chemi- cal Elements), 274-5 Burning, as known in chem- istry, 18; nature of, in gases other than oxygen, 93 ; as instance of chemical action, 227 Butane (see Alcohols), 220, 224 Butter, 225 Butylenes (see Butanes, Al- cohols), 224 Cadmium, characteristics, symbol of, uses of, 173 Cadmium Sulphide (see Cad- mium, uses of), 173 Caesium, 195 ; discovered by spectroscope, properties of, 202; (see also Table of Chemical Elements), 2~74 Calcic Sulphate, uses of, 206 Calcium, sodium borate in compounds with, 199 ; sym- bol of, a metal, 203; dis- covered, 266 ; ( see also Table of Chemical Ele- ments), 274; (see also Ta- ble of Elements in Earth's Crust), 277; and Freezing Mixtures, Crystallized Chloride of, 282 Calcium Carbide, Acetylene gas derived from, 205 Calcium Carbonate (see Ex- periments of Cavendish), 264; formula of (see Chalk), 280 Calcium Chloride, Affinity of, for water, mercury artifi- cially frozen by combina- ation of, with snow, 206 Calcium Hydrate (see Slaked lime, Table of Common Names), 281 Calcium Hydroxide, symbol of (see Slaked lime), 205 Calcium Light (see Quick- lime), 205 Calcium Oxide, symbol for, 205; (see Lime, Table of Common Names), 281 Calcium Sulphate (see Plas- ter of Paris, Table of Com- mon Names), 281 Calico Printing, borax used in, 207 California, sodium borate found in, 199 Calomel (see Mercurous Chloride, and formula of, Table of Common Names), 280 "Calx of Mercury" (see Priestley's Experiments ) , 263 Cannon, steel prepared for (see Processes of Steel manufacture), 154 Carbide of Boron, 89 (note) ; Carbolic Acid, 280; use of, in Picric Acid, 283 Carbon, nature of, 81-82 ; im- portance of to human life, combination of, with oxy- gen, 84; compounds of, 86- 87, 213-226; where found pure, substances of which, is essential part, 87; quali- ties of, 88; three forms of, 89 ; theory concerning dif- ference in forms of, 91 ; in- cluded in group of ele- ments, 108 ; chlorine does not combine readily with, 112; atomic weight of, changed, 127 ; relative amounts of, in wrought and cast iron, and in steel, 149; comparative importance of, in organic life, 208; dis- tinction of, from other ele- ments, 213; compound of hydrogen with (see Hydro- carbon), 215-216; result of hydrogen combined with, 218; study of, brought about, 267; temperature of vaporization ( Thermome- ter), 276; proportions of 290 INDEX in rain water (Table), 280; (see also Table, Periodic System), 255-8; (see also Table of Elements on Earth's Crust), 277 Carbon Atoms, linking of, 214 Carbon Boride (see Iron), 206 Carbon Compounds, 213-226; concerning theories of, 226 Carbon Di-Oxide, dough raised by, 198; action of water containing (see Limestone), 203; experi- ments with, 264 ; ( see also Carbon Compounds), 218 Carbon Di-Sulphide, how formed, uses of, 125 Carbon Filaments, in electric lighting, tungsten filaments compared with (see Elec- trical work), 183 Carbon Monoxide (see Car- bon compounds), 218 Carbonates, of alkalies, 263; of lithium, 202; of potas- sium, 201 ; of soda ( see Freezing Mixtures), 282 Carbonic Acid Gas, discovery of, 263 Carborundum, 209 ; product of electric furnace, 232-3 Carnelian (see Crystal sili- cate), 208 Cast Iron (see Iron), 146-7 Cathode (see Faraday's ex- periments with electrolysis), 235 Cations, metals as (see Fara- day's experiments with electrolysis), 236 Caustic Potash (see Potas- sium hydroxide), 200; (see also Table of Common Names), 280 Caustic Soda (see Table of Common Names), 280 Cavendish, Henry, 263 ; re- searches and discoveries of, 264; (see also Hydrogen, Table of Chemical Ele- ments), 274 Cements (see Uses of sili- cates), 209; (see Lime- stone, building lime), 204; hydraulic, Portland, Rosen- dale, 205 Ceylon, potassium found in, 199 Cerium, Table of Chemical Elements, 274 Chalk, formations of, chalk cliffs (see England), 204; (see also Table of Common Names), 280 Chemicals, Divisions of, 97; Tables of Common Names of, 280 Chemical Action, 227-243; re- lation of, to forms of en- ergy, 229; modern benefits from study of, 229; origin of laws of, 253 Chemical Aflinity, qualities known as, 94 Chemical Combinations, Na- ture of, 93-106 Chemical Compounds, use of saltpetre in, 201 Chemical Elements, Symbols of, 69-70; table of, 274-5 Chemical Equations, correct, 71 ; value of, recorded, 72-3 Chemical Formulae, system of letters and numbers for (see Berzelius), 265 Chemical Law, 245 Chemical Nomenclature, 283 Chemical Processes, wonders of modern, 228 Chemical Study, attempts to systematize, 269-70 Chemical Symbols, value of, 72 Chemistry, as a mature science, 8; what is of practical, 85; part of ni- trogen in "organic," part of nitrogen in inorganic, 40; distinct from physics, 67; foundation of modern (see Boyle), 76-7; story of, 261-284 ; way to conquest of INDEX 291 " organic ", opened, 267 ; sciences of electricity and, united, 266; Liebig's re- searches in agricultural, 267 Chalcedony (see Crystalline silica), 208 Charcoal, nature of, 28-9; method of burning sub- stances into, 29; how ob- tained, 85; (see oxygen), burned by nitric acid, 190; proportions in gunpowder of, 282 Chili, sodium nitrate found in, 199 Chili Saltpetre (see Chili), 199 Chloral (see Alcohols), 221 Chlorides, silver (see Silver), 138; ferric (see Ferric Salts), 156; in solution, in chemical tests, 241 Chloride, of ammonium (see Freezing Mixtures), 282; of magnesium (see Table Salt), 196; of radium, 271 Chlorine, sodium and phos- phorus burn in, 30 ; propor- tion of, in salt, 75 ; combi- nation of, with hydrogen, 93; in group of Halogens, 108-9; defined, 109; descrip- tion of, effect of, uses of, separation of, from common salt, 110; efficacy in disin- fecting and bleaching, 111 ; atomic weight of, effect of, upon burning charcoal, 112 ; experiments of Dumas with, 208; proportion of, in rain water (see Table), 280; (see also Table, Peri- odic System), 255-7 (and Tables), 274, 277 Chlorine Gas, elements that burn in, 112 Chloroform (see Alcohols), 221 Chrome Alum, uses of, 182 Chromium, description of, ex- traction of, compounds of, effect upon steel ; 182-3 (see also Tables), 274-77 Chrome Yellow, 182 Cinnabar (see Mercury Sul- phide), use of, to artists, 119; (see Mercury), 170; two forms of, 171 Cider, "Mother of Vinegar" in, 223 Citric Acid (see Organic acids), 223 Clarke, F. W., relative amounts of elements esti- mated by, 277 Claus (see Ruthenium, Ta- ble), 275 Clay (see Silicates), 209; pottery (see Aluminium Silicate), 179 Cleansing Agents (see Borax) , 207 Cleve (see Thulium, Table), 275 Coal, importance of, 79; or- igin of, 80-81, 85 ; result of distillation of, 81; bitu- minous, lignite, 90; point of ignition of (Thermome- ter), 276 Coal Gas, apparatus for manufacture of, 83 Coal Tar (see Carbon Com- pounds), 224-225-226 Cobalt, discovery of, descrip- tion of, affinity of oxygen for, effect of heat on salts formed by combinations of, variety of, in pure state, salts formed by combina- tions of, 157; uses of, in arts, 158; included in platinum group, 164; (see also Table), 274 Coke, how made, 91 " Century's Progress in Chem- istry, The" (see Williams), 266 Cold, greatest natural, degree of, greatest artificial, de- gree of (Thermometer), 276 292 INDEX Combustion, nature of (see Priestley's Experiments ) , 263; (cf. combustible and oxidizable), 18 Compounds, classification of, how fixed, 96-7-8; acid, base, 107 Converter (see Bessemer process), 152-3 Copper, vapor of sulphur com- bined with, 93; color of, 130; amounts of, found pure, 131 ; ancient discov- ery and use of, 139 ; ( see Copper Age) ; atomic weight of, chemical symbol for, de- rivation of, name of, specific gravity of, 140; alloys of, 140-1 ; properties, qualities, uses, compounds of, 140-2; two classes of compounds of, 141 ; pigments derived from, carbonate of, 142; use of, in coloring glass, 210; (see also Tables of: Periodic System), 255-8; (Chemical Elements), 274; (Conductivity of Metals), 279; (see Blue Vitriol), Common Names of Metals, 281; Alloys, 284; melting point of, 276; acetate (see Verdigris), 142-281 Copper Age, 139-144 Copper Compounds, danger- ous, chief uses of, 142 Copper Vessels, danger of, for food, 142 Copperas (Table of Common Names), 280 Coquina, 204 Cordite (see Blasting Gela- tine, Explosives), 283 Corrosive Sublimate (see Mercury Chloride), uses of, 171; Table of Common Names, 280 Corundum (see Oxides of Aluminium), 178 Courtois (see Iodine, Table of Chemical Elements), 274 Cream of Tartar (see So- dium), 198; how formed, 224; (see Potassium bitar- trate, in Table of Common Names), 280 Crondstadt (see Nickel, Ta- ble of Chemical Elements), 275 Crookes (see Thallium, Table of Chemical Elements), 275 Crown Glass (see Glass), 211 Crystalline Silica, 208 Cupric (see Copper com- pounds), 141 Cuprous (see Copper Com- pounds), 141 Cuprous Oxide, symbol for, uses of, 142 Curi (see Radium, Table of Chemical Elements), 275 Cyanide of Potassium (see Potassium Cyanide), 201 D Davy, Sir Humphrey, 175; composition of salt proved by, 196; experiments of, in electrolysis, 235; union of chemical and electrical sciences begins with, 266; (see also Table of Chemical Elements), 274-5; (in re: boron, barium, calcium, magnesium, sodium, potas- sium, strontium) Dalton, John, 10-11-15; re- searches of, 10; biographi- cal sketch of, 11 ; discovery of, concerning elements in combination, 16; theory of, 245 ; demonstration concern- ing gases, 248 ; theories first put forth by, 264 Decay (see Oxidizing), 28 Del Rio (see Vanadium), 275 " Dephlogisticated Air" (see Oxygen), 263 Deville, Ste. Claire, alumin- ium prepared by, 175 INDEX 293 Dextrose (see Glucose, or Grape Sugar, Table of Com- mon Names), 280 Diamond, nature of, 81 ; Mois- san's electric furnace for making, 90-1 (see Carbon Boride), 206; (see Prepara- tion of Carborundum ) , 233 ; (hardness of Carborundum compared with) Diethyl Oxide (see Ether, Table Common Names), 280 Dioxide (Carbon) (see Car- bonate of Copper), 142 " Disassociation," theories of atomic, 269 Disinfectants (see Formalin), 221; (see Lime), 205 Dolomite deposits of (see Magnesium Calcium Car- bonate), 174 Double Decomposition, de- fined, 94 " Drummond " Light (see Cal- cium Light), 205 Drying Agents (see Calcium chloride), 206 Dulong, experiments of, 266 Dulong and Petit, Law of, 251 Dumas, demonstration of, 267- 68; in relation to theory of compounds, 270 Dyes, aniline, 40 Dyeing, acetates used in, 223; borax used in, 207; Glaub- er's Salt used in, 199 Dynamite (see Explosives), 283 Earth, foundation of crust of, 21 Earths, Alkaline, 263 Electricity, bromine separated from bromides by, 112 ; met- als conductors of, 130; ap- plication of magnetization in mechanical electricity, 155; uses of platinum in handling of, 162; carbon filaments compared with Tungsten in electrical ap- paratus, 183; action of, on organic life, 216; solutions which conduct, 240 Electric Action (see Elec- trons), 63 Electrical Apparatus, short circuits prevented (see Bis- muth), 184 Electric Arc, Temperature of (see Thermometer), 276 Electric Batteries, copper sul- phate useful in, 141 ; use of zinc in, 172 ; use of hydro- chloride in, 188 Electric Current, action of, 42-3 Electric Machine, 120 Electrode (see Electrol, Fara- day's experiments), 236 Electrolysis, 233-238; alumin- ium extracted by 177; dis- covery of, 233 ; experiments in, 234-5 ; measurement of electric current in, 236; re- lation of metals and non- metals in, 236; measure- ment of work of electric current in, 237; theoretical explanation of, 238; rela- tion of disintegration of atoms to, 253 Electrolyte (see Electrolysis, Faraday's experiments), 235 Electrons, Sir Oliver Lodge in regard to, 59-60; how elec- trified, movement of, 61 : freeing of negative, 63; atoms made up of, 64 ; hypo- thetical ly not matter, 66; in radio-active bodies, 273 Electro-Plating, 232 Elements, replaced by "prin- ciples," 9 ; theory of simple, 50; proportion of, in com- pounds, 73; Table of fre- quent, Table of rarer, 75; Dal ton's discovery concern- ing proportions of, 76; the 294 INDEX four great, 84-5 ; number of, 96 ; commoner, groups of, 107-127 ; non-metal group of, 107; group of, in chem- istry, 108; proportions of, indicated in atomic weight, 116; metallic, 128-211; com- parative weights of (see Chemical Law), 245; "com- bining weight" of (see Chemical Law), 246; pro- portionate weights of (see Chemical Law), 246-7) ; re- lation in ordering of (see Periodic Law), 253-4; val- ency of, defined, 254-6; named according to valency, 256; variations of propor- tions of, 257; Dr. Wollas- ton's demonstration con- cerning, 265 ; limit to com- bination of, illustrated, 268 ; Table of Elements in Earth's Crust, 277 Elihrjar, d' (see Tungsten, Table of Chemical Ele- ments), 275 Elixir of Life, 9 Emerald (see Aluminium sili- cate), 178; Glucinum found in), 185 Emery (see Oxides of Alu- minium), 178 Enamel, borax used in manu- facture of, 207 Energy, relation of chemical action to forms of, 229, 230- 231 ; heat, example of tak- ing up of, light, example of taking up of, 231 ; electric, examples of taking up of, 231-2 England, chalk cliffs in, 204 Epsom Salts (see Magnesium Sulphate ) , 125-174 ; ( see also Table), 280 " Equivalents," elements com- bine in, 253, 257 Erbium (see Table), 274 Etching, Nitric acid used in, 190 Ethane (see Hydrocarbons, 218, 220, 224), formula for (footnote), 223 Ether, Atmospheric, motions of, 61-2 Ether (Diethyl oxide), how prepared, uses of, 222; Ta- ble of Common Names, 280 Ethyl (see Alcohols), radicals forming, 220 Ethyl Alcohol, in preparation of ether, 222 ; formula for (footnote), 223 Ethylene (see Carbon com- pounds), 218; Table of Common Names (Olefiant gas), 281 Explosives, given by nitrogen, 40 ; use of saltpetre in, 201 ; Sir A. Noble's and Sir F. Abel's researches with, 278 ; Table of, 282-3 F Fahrenheit, derivation of scale of, 277 Fats, ether used to dissolve, 222 Faraday, work of, in experi- ments with electrolysis, 235 ; Law of (see Electrolysis), 237 Feldspar (see Silicates), 199, 209 Ferric Hydroxide, 155 Ferric Salts, colors of, 156 Ferrous Sulphate (see Green Vitriol, Table of Common Names), 281 Fertilizer, use of gypsum as, 206; use of lime as, 205; use of sodium nitrate as, 199 Fire, as affect of oxygen on matter, 18; ancient ideas of, 227; story of chemistry begins with use of, 261 Fire-Dnmp (see Methane), 218-219; Table of Common Names, 280 INDEX 295 Fireproofing, silicates used in, 209 Flint (see Crystalline silica), 208 Florida, Coquina in, 204 Fluorine, group of Halogens includes, 108 ; description of, atomic weight of, hydro- fluoric acid, compound of, 114; characteristics of, oxy- gen does not combine with, 115; weights of, group, in order, 116; atomic weight of, changed, 127; Table of Chemical Elements, 274 ; Table of Elements in Earth's Crust, 277 Food Preservatives (see Borax), 207 Food Stuffs, Liebig's improve- ments in, 267 Formaldehyde (see Forma- lin), 221 Formalin (see Aldehydes) 221 Formic Acid, 221 Franklin, Benjamin, aid of, to Priestley, 262 Freezing Mixtures, Table, 282 Fruit Juices, elements con- tained in, 87 G Gahn (see Manganese, Table of Chemical Elements), 2T4 Gas, Acetylene (see Carbon compounds), 205; prepara- tion of, 219 ; hydrogen com- bined with, 218; production of, 232; Illuminating, how derived, 84 Gases, recently discovered in air, list of rare, in atmos- phere, 20-1 ; combining of (footnote), 76-7; theory of pressure of, consistency of, 248; volume of, 253; rare, 256 ; discovery of weight of, 264; combination of (see Gay-Lussac), 265 Gas-Metal (see Radium ), 255- 58 Gay-Lussac, 265, 274; dis- covery of cyanogen by, 267 Gadolinium, Table of Chemi- cal Elements, 274 " Galena" (see Lead), 167, 169; lead sulphide named, 119; Table of Common Names, 280 Gallium, 258 ; Table of Chemi- cal Elements, 274 Garnet, silicate of alumin- ium contained by, 178 Gelatine, Blasting (see Ex- plosives), 283 Germanium, 258; Table of Chemical Elements, 274 German Silver (see Table of Alloys), 284 Germany, Reaumur's scale used in, 277 Glass (see Silicon), 209-211; process of whitening, 182; uranium used for coloring, 183-4; fused quartz used as, water, 209; colored, flint, Bohemian, first made, 210; annealing of, iron oxide in, 211 ; making of plate, 210 Glass Making, Glauber's Salt used in, 198; Carbonate of potassium used in, 201 ; borax used in, 207 Glauber's Salt (see Sodium sulphate), 198, 125; Table of Common Names, 280 Glucinum, how found, de- scription of, salts of, 185 Glucose (see Grape Sugar, Table of Common Names), 280 Gold, 130, 135 ; atomic weight of, 134; properties, quali- ties and uses of, 132-3-4-5, 210; symbol of, 134; melt- ing point of pure (Ther- mometer), 276; (see also Tables of Periodic System), 296 INDEX 255-8 ; ( Chemical Elements ) , 274; (Alloys), 284 Goulard Water (see Basic Acetate of Lead (Table), 280 Graphite, nature of, 81; compared with diamond, 89 Green Vitriol (see Iron Sul- phate), 125 Gun Cotton (see Explosives), 283 Gun Metal, Table of Alloys, 284 Gunpowder, 199; as example of unstable compounds, 230 ; igniting point of (Ther- mometer), 276; (see also Table of Explosives), 282 Gypsum (see Calcic Sul- phate), 125, 203, 206 H Hall, Process, aluminium ex- tracted by, 177 Halogens, Group of, 108; de- rivation of word, 109 Harper's Magazine (see Arti- cle by Henry Smith Wil- liams), 266 Hartshorn Spirits (see Am- monia), 187 Hatchett (see Tantalum, Ta- ble of Chemical Elements), 275 Heat, influence of, in forming new bodies, 10; Robert Boyle in relation to influ ence of, 10 ; metals, conduc- tors of, 130 ; a sign of mo- tion, relation of, to chemical action, 229-232; effect of, on molecular motion, 248; degree of orange red, of dull red (see Thermome- ter), 276 Helion, 21 Helium, 256, 272; (Table of Chemical Elements), 274 Herman (see Cadmium, Table of Chemical Elements), 274 Hinrichs, 270 Hisinger (see Cerium, Table), 274 Hjelrn (see Molybdenum, Ta- ble of Chemical Elements), 274 Horn Silver, 136 Human Body, Temperature of, in health (Thermome- ter), 276 Hydraulic Cement, 205 Hydrates, 103; Sodium, Ta- ble of Common Names, 280 ; ferric (see Ferric Salts), 156 Hydrocarbons, 216; (see Com- pounds of Carbon), 218-220 Hydrochloric Acid (see also Muriatic Acid and Spirits of Salt, Table), 281; pro- duction of, 93; result of zinc combined with, 93-4; use of, to dissolve gold, 134; (see also Freezing Mixtures), 282 Hydrochloric Acid Gas, meth- ods of obtaining, 111 Hydrochloride, uses of, in electric batteries, 188 Hydrofluoric Acid, use of, in the arts, glass corroded for etching by, 114; density of, combination of, with met- als, elements that unite with, oxygen does not unite with, 115 Hydrogen, 12 ; experiments with, 24; theory of, com- parative weight of, 47-48; as unit of weight, 48-49; theory concerning, 65-66 ; attraction of oxygen for, 95 ; freezing of, by sodium, 196 ; method of releasing, 200; lithium unites with, 202; combination of carbon with, 215-216; Priestley's experi- ments with, 263; Table of Chemicals, 274 ; freezing point of (Thermometer), 276) ; liquefying point of (Thermometer), 276; Ta- INDEX 297 ble of Elements of Earth's Crust, 277; diameter of molecules of (Table), 279; Light Carburetted (see Fire-damp, Methane), 280; (Table), Sulphuretted, 122 Hydroxides, 103; method of formation of, 200; metallic, replaced by radicals (see Alcohols), 221; (see Metal- lic Oxides, Table of Alloys), 284 Hydroxyl (see Radicals form- ing alcohols), 220; see Preparation of ether), 222; see Ionic theory of neu- tralization), 242 Hypo (prefix), (see Chemical Nomenclature), 283; "hypo" (see Sodium thio- sulphate), 138 Hypo Sulphite of Soda, use of, 125 Ic (Termination) (see Chemi- cal Nomenclature), 283 Ice, Temperature of mixture of salt and (Thermometer), 276) ; pounded (see Freez- ing Mixtures), 282 Iceland Spar (see Calcium) Illuminating Gas, presence of ethylene in, 219 Incandescent Electric Lights, use of Tungsten in, 183 Infusorial Earth (see Kiesel- ghur), 283 Inks, what combined to make, 156 Inorganic Compounds, silicon foundation of, 258 Invar (see Table of Alloys), 284 "Invisible College," 262 Iodides, action of, 114 Iodine (see Halogens), 108; atomic weight of, 113; ef- fect of heat upon, uses of, vapor of, compared with air, solutions of, effect of combination of, with phos- phorus, uses of, in medicine, 114 ; in compound of iodo- form, 222; (see Table of Chemical Elements), 274 lodoform (see Alcohols), 222 Ions (see Electrolysis, Fara- day's experiments), 236 Ionic Theory, neutralization explained by, 242 Iridium, hardness of, 130; (^ee Description of plati- num), 161; platinum group includes, uses of, 164; (see Table of Chemical Ele- ments), 274; melting point of (see Thermometer), 276 Iron, especially treated of, 143-157; vapor of sulphur combined with, 93 ; benefit to mankind of, 143-4; steel, as form of, 144; uses of, 144-8; rarity in pure state, 145; where plentiful, 146; ores of, 146; difference be- tween cast and wrought, 148-9; Bessemer process of converting, 152 ; processes removing other elements from, 153 ; magnetization of, qualities of, 154; im- portance of manner of mag- netization of, 155; effect of moisture upon, effect of iron rust in relation to electricity, manner of pro- tection of, 155; platinum group includes, 164; red hot, visible in dark, degree of heat of (Thermometer), 276; (see also Table: Chem- ical Elements), 274; (Ele- ments in Earth's Crust), 277; (Conductivity of Metals), 279; (Common Names), 280; cast, 146-7; melting point of cast, 276; pig, 146; wrought, quali- ties and uses of, process of making, advantages of, over 298 INDEX cast, 148-9; process of add- ing carbon to wrought (see Bessemer), 152; melting point of wrought (see (Thermometer), 276 Iron Age, 144 Iron Compounds, where found, 145-6; two general classes of, 155-6; main uses and value of, 157 Iron Industry, uses of lime- stone in, 204 Iron Pyrites (see Table of Common Names), 280 Isomerism, 269 Isomorphism, discovery of, 266 Jasper (see Crystalline silica), 208 Jeans, diameter of molecules ascertained by, Table, 279 Jeweler's Putty, Table of Common Names, 280 Kelvin, Lord, analogy of atomic theory, 58 Kieselghur, Proportions in dynamite, Table of Explos- ives, 283 Kirchloff (see Caesium, Table of Chemical Elements), 274 Klaproth (see Titanium, Ta- ble of Chemical Elements), 275 Krypton, 21, 256; Table of Chemical Elements, 274 Lactic Acid (see Organic Acids), 100, 223 Lanthanum, Table of Chemi- cal Elements, 274 Lavoisier (see Azote), name given by, 40; explanation of composition of water, 41 ; (see Oxygen and composi- tion of air), 262-3 Laughing Gas (see Nitrous oxide), 189; Table of Com- mon Names, 280 Law of Octaves (see John Newlands), 270 Lead, hardness of, 130; de- scription of, symbol for, ores of, processes of ex- traction from ores, 167; comparative weight of, 167- 68; uses of alloys of, com- mercial uses of, monoxides of, salts of, 168; Sugar of, 169 ; relation of to uranium, 273; (see Table of Chemi- cal Elements), 274; point of fusion of (see Ther- mometer), 276; Table of Conductivity of Metals, 279; Table of Alloys, 284; Acetate of (see Decomposi- tion, experiments in Elec- trolysis), 235; (see Goul- ard Water, Sugar of Lead, Table of Common Names), 280-1 ; Commercial, where derived, 167 ; red, uses of, 168; white, 169; chromate, 182; sulphide (see Galena), 280; (Table of Common Names) Leather, how preserved, 196 Lenses (see Plate Glass), 210 Leyden Jar, 234 Liebig, Studies and achieve- ments of, 267 ; discovery of isomerism by, 269 Life, Organic agencies affect- ing, interchange of sub- stances in, 216 Light, hypothesis concerning origin, 63; action on or- ganic life, 216; chemical combinations producing, 230 ; effect of, on unstable compounds of silver in photography, 231 Light Rays, new kinds of (see " Fourth State of Mat- ter)," 65 Lime (see Calcium Oxide), INDEX 299 uses of, properties of, how obtained, slaked, 205; (see Table of Common Names), 281 Limes, for building, 204 Limestone, dissolution of, 203 Lime Water (see Calcium hydroxide), 205 Liquids, character of, acid and alkaline, 9-10 Liquid Metal (see Mercury), 255-8 Lithium, 195; properties of, comparative weight of, 202 ; (see Table of Periodic Sys- tem), 255-7; (Table of Chemical Elements), 274; ( Elements in E a r t h's Crust), 277 Lithium Carbonate, use of, 202 Litmus Paper, defined, use of, 99; alkalies tested by, 103; effect of solutions of salt upon, 104 Lockyer (see Table), 274 Lodge, Sir Oliver, 59-60; hypothesis of, concerning hydro-electrons, 59-60 Lulli, Raymond, 261 Lunar Caustic, 137-8; (Table of Common Names), 281 Luray Cavern, 204 Lyddite (see Picric Acid, Ta- ble of Explosives), 283 M Magic, relation of history of chemical action to, relation of properties of elements to ideas of, 228 Magnesium, symbol for, 173; abundance of, melting point of, properties of, 174; (see Glucinum, 185 ; Tables, 255- 57, 277; phosphates of, 174; calcium carbonate, 174 ; oxide, use of in medicine, 174; sulphate (see Epsom Salts), 125; uses of Com- pounds of, 174; Table" of Common Names, 280; oxide (Magnesia), 174 Magnetic Alloy, Table of Al- loys, 284 Magnetization, of iron, of steel, 154 Malic Acid (see Organic Acids), 223 Mammoth Cave, 204 Manganates (see Manganese), 181 Manganese, atomic weight, 127; uses of, weight of, point of fusion of, 180-2; (see Sodium borate), 199; (see also Tables), 274, 277, 284 Marignac (see Table), 275 Marsh Gas (see Methane), 218 Matter, two kinds of divis- ions of, 13 ; defined by phys- ics, constantly divisible, 51; "fourth state" of, "dead" theory of, 64-5; three states of, 247 ; Boyle's view of, 262 Meat, elements contained in, 87; cured (see Rock Salt), 196 Mendeleef, Improvement of Periodic System by, 254-5; new substances predicted by, 258-9, 270 Melinite (see Picric Acid* Explosives), 283 Mercuric Chloride (see Cor- rosive Sublimate, Table), 280 Mercurous Chloride (see Calo- mel, Table), 280 Mercury, atomic weight of, changed, 127 ; description of, ores of (see Cinnabar), symbol of, uses of in medi- cine, uses of amalgams of, physiological effect of, 170- 71-2; artificially frozen, 206; boiling and freezing points of (Thermometer), 300 INDEX 276; conductivity of (Ta- ble), 279; (see also Tables), 255-8, 275 ; fulminating, 171-2; iodide, uses of, 171; chloride, uses of, 171 Metalfic Salts, 279 Metals, beliefs of alchemists regarding, 7-8 ; elements forming bases, ranked with, 97 ; early definition of, 128 ; distinction of, 'from non- metals, modernly defined, 129; white, 129-30; colors of, 129-30; combination of oxygen with, 130; combina- tion of hydrogen and oxy- gen with, 130; qualities of, compounds or ores of, mix- tures of (see also Alloys), variation of specific gravity of, extraction of, from ores, found in pure form, 130-1 ; earliest use of, 261 ; terminology applied to, 283 Meteorites, iron in pure state in, 145; occurrence of nickel in, 159 Methane (see Carbons, hydro- carbons), 218, 220, 224 Methyl Alcohol (see Carbon compounds, Alcohols, radi- cals forming), 219-220 Meyer, improvement of Peri- odic System by, 254, 270 Mica (see Silicates), 209 Milk, 225 Milk of Lime (see "White- wash)," 205 Minium (see Red lead), 168 Moissan, experiments of, with diamonds, 88-9 ; electric furnace of, 90-1 Molecular Weight, meaning of, 251 ; means of finding, 240; (see Solutions) Molecules, definition of, 52; matter made up of, 64; formula for, 70-1 ; move- ments of, in gases, 247-8; proof concerning, 268; re- lation of, to composition of matter, 273; Table of diameters of, 279; com- pound, theory of, 265 Molybdenum (see Chromium), 183, 276 Monad (see Units of Val- ency), 214 Mono (prefix) (see Chemical Nomenclature), 283 Monoxides (see Metallic Ox- ides, Table), 284 Mordants, Alums known as, 179 Mosaic Gold (Tables), 274 Mosander (see Table), 274-5 "Mother of Vinegar" (see "Organic Acids)," 223 Multiple Proportions, Law of, 76 Muriatic Acid (see Hydro- chloric acid), 111 N "Natural Gas" (see Me- thane) " Negative Gravity " (see Me- thane), 263 Neodymium (Table), 275 Neon (Table), 275; and pp. 21, 256 Neutral Substances, all salts not, 104 Neutralization, Ionic theory of, 242 Newell's "Descriptive Chemis- try," Formulas from, 223 Newlands, Periodic Law sug- gested by, 254; also, 270 Niagara Falls (see Manufac- ture of Carborundum), 233 Nickel, valuable quality of, in manufacturing, alloys of, 158; (also see Table of Al- loys ) , 284 ; properties of, cf. w. iron, occurrence of in pure state, 159; Tables, 275, 277 Niobum (see also Columbum, Table), 275 INDEX 301 Nitrate, potassium, 189, 199, 200, 281; silver, 137, 138; sodium, 189, 199 ; strontium, 185 Nitrates and Nitrites, propor- tion of, in rain water (Ta- ble), 280 Nitric Acid (see Compounds of Nitrogen ; also see Aqua fortis), use of, to dissolve gold, 134; preparation of, formula for, 189-90 ; sodium nitrate used in making, 199; analysis of, by Caven- disb, 263-4; (see also Ta- ble), 280; Explosives, 283 Nitrogen, combined with oxy- gen, 16; modification of oxygen by, 27 ; means of obtaining free, proportions of atoms in, 35; properties of, use of, in nature, 36; bow readily prepared, 38; discovered, absorbed by plants, fertilization of soil by, 39; compounds given rise to by, in organic cbern- istry, in inorganic chemis- try, 40; in group of ele- ments, 108; compounds of, 185-191; how obtained, 185- 86; lithium unites with, 202 ; addition of, to hydro- carbons, 216 ; experiments of Priestley with, 263; Ta- bles, 275, 279, 280 Nitroglycerine (see Explos- ives), 283 Nitro Hydrochloric Acid (see Aqua Regia, Table), 280 Nitrous Oxide, 189; (Table), 280 Noble, Sir A., researches of, with explosives, 278 Non-Metals, elements known as, 97, 109; early definition of, 129 ; compounds of, 130 Normal Salts (see Table), 279 O Oersted, Compound of chlo- rine and aluminium made by, 176 Oils, ethers used to dissolve, 222 Olefiant Gas (see Ethylene), 218, 281 Olive Oil, 225 Organic Chemistry, way to conquest of, 276 Osmic Acid, 256 Osmium * (see Description Platinum), 161; uses of, 164 ; Table, 256 ; Thermome- ter, 276 Opal (see Silica), 208 Organic Acids, 222 Organic Chemistry, 268 Organic Compounds, 217 ; car- bon as foundation of, 258 Organisms, chief elements en- tering into, 215 Ous (termination) (see Chemi- cal Nomenclature), 283 Oxalic Acid (see Organic Acids), 223; (see Salts of Lemon), 281 Oxides, how produced, com- parative weight of with air, 28 ; combination of oxygen and metals form, 130 ; acid- forming, basic, higher, me- tallic, Table, 284; copper, 142; ferric (see Ferric Salts), 156; iron, 27; lead, 281 (Table) ; tin (Table), 280 Oxidize, 18 Oxidizing, equivalent to burn- ing, 31 Oxydizing Agents (see Chromium), 182 Oxygen, agent in changes, combined with nitrogen, meaning of name, 16; comparative amounts of, re- ceived by man and creat- ures, 17; hibernating ani- mals need of, 18; where found especially, 21 ; literal meaning of, method of ob- taining by itself, discovery 302 INDEX of, 22; experiments with, 24 ; made commercially, method of obtaining, prop- erties of, 25; readiness to combine with other ele- ments, 26; heat and light caused by action of, 27 ; ac- tion of, upon blood, 29; condensed, 32; atom of, as standard of weight, 50; strong attraction for hydro- gen, experiment with, 95-6; groups of elements includ- ing, 108; element that does not combine with, 115 ; sul- phur group includes, 116; atomic weight of, 126-7 ; af- finity of cobalt for, 157; action of on potassium, 200 ; lithium unites with, 202; abundance of (see Silicon), 210 ; effect on hydrocarbons, 216; discovered, 263; Ta- ble, 277; diameter of mole- cules of, 279 Oxy hydrogen Flame (Ther- mometer), 276 Ozone, 31 ; expansion of, con- densation of, 32; discov- ered, most abundant in, as a disinfectant, as an oxi- dizer, produced in thunder- storm, 33 Palladium (see Metals in ore of Platinum), 161; cf. prop- erties of platinum, 163; laboratory use of, platinum group includes, 164 ; Table, 275 Paracelsus, 261, 275 Paraffin, melting point of ( Thermometer ) , 276 Paraffin Series (see Hydro- carbons), 218, 220 Paris Green (see Organic Acids), 223 Pasteur, 267 Pearlash (see Carbonate of Potassium), 201 Peat (see also Coal), 90 Pentane, 224 Per (prefix) (see Chemical Nomenclature), 283 Periodic Law, Explanation of Table of, 254-6 Periodic System, Elements classified by, 213 ; relations in valency demonstrated by, 257 ; Table of, 259, 270 Permanganates (see Manga- nese), of potassium, uses of, 181 Peroxides (see Metallic Ox- ides, Table), 284 Petit, experiments of, 266; Dulong and, Law of. 251 Petrified Wood (see Silica), 208-9 Phenol (see Carbolic Acid, Table), 280 Pewter, 170; alloy of (see Table), 284 " Philosopher's Stone," 9 Phlogiston, 263 Phosphates, necessity of, for fertilization of soil, 19, 23 Phosphorus, combines with oxygen, 27, 30 ; group of ele- ments includes, 108; chlo- rine melts and burns, 112; effect of combination with iodine, 114; preparation of red, yellow, black, respect- ively, forms of, characteris- tics of, where found, uses of, 191-2 ; frequency of, 217; melting point of (Ther- mometer), 276; (Tables), 255-7, 275, 277 Photographic Lenses (see Silicon), 200 Photographic Operations, use of litmus paper in, 100 Photography, Chemistry of, 138; effects of light on un- stable compounds of silver in, 231 ; spectra studied by, 270-1 INDEX 303 Physics, function of, realm of, as distinguished from chemistry, 54-5 Picric Acid (see Explosives), 283 Pig Iron (see Iron), 146 Pigments, acetates used in making, 223 Pitchblende, " rays " abund- ant in, 271 ; proportions of radium and uranium in, 273 Plaster of Paris, 125, 281 Plate Glass, 210 Platinum, 161-5 ; description of, derivation of name of, rare metals contained in ore of, 161 ; process of pre- cipitating, 161-162; labora- tory use of, use of in elec- trical manipulation, 162 ; general uses of, 162-3 ; " oc- clusion " of, 163 ; proper- ties of, 163-4; crucibles for melting, 205; melting point of (Thermometer), 276; (see also Tables), 275, 279 Platinum Group, properties of, elements in, 164-5 Platinum Paper, 20 Platinum Wire, laboratory use of, 207 Pneumatic Trough, 23 (see also Priestley), 263 Polonium, 273; (see also Hel- ium), 273 Potash (see Carbonate of Po- tassium), 201 Portland Cement, 205 Potassium, acids neutralized by, 103; compounded with chromium, 182, 195; occur- rence of, symbol of, salts of, description of, extrac- tion of, test for presence of, as pure metal, 200, 202; silicates of, 209; experi- ments of Sir H. Davy with, 266; Tables, 275. 277; Anti- mony Tartrate (see Tartar Emetic, Table), 281; Bi- tartrate (see Cream of Tar- tar), 280; bromide, bromine extracted from, 112: bro- mide, use of in medicine, 113; Carbonate (see Salt of Tartar, Table), 281; chlo rate, 201 ; cyanide, uses of, 201 ; hydrate (see Caustic- Potash, Table), 280; hy- droxide, uses of, 200; nitrate, use of in prepara- tion of nitric acid, 189; ni- trate, sodium nitrate used in making, 199; nitrate (see Saltpetre, Table), 281; sul- phate, 179; uses of, 201 Pottery, three classes of (see Aluminium silicate), 179 Pottery Clay (see Aluminium silicate), 179 Praseodymium, Table, 275 Precious Stones, making arti- ficial (see Flint Glass), 210 Precipitate, definition of, 96 Preservatives (see Formalin), 262 Priestley, 262, 263, 275; ex- periments of, 263 Propane (see Hydrocarbons), 218, 220, 224 Proportions, combining of elements, 245 ; Law of Definite, 76 ; idem, 245, 264 ; Law of Multiple, 245 (see Dalton), 264 Propyl (see Alcohols, radicals forming), 220 Propylenes, 224 Proust (see Law of Definite Proportions), 76, 264, 270 Pyrites (see Iron) Q Quartz (see Silicates), 208; fusion of, 209 ; Table, 281 R Radicals, effect of occurrence of, in Carbon compounds, 217-218; relation of, to bin- ary combinations, 267, 268 304 INDEX Radio- Active Bodies, Elec- trons in, 273 Radio-Activity, explained, 63 Radium (see Radio-activity), 63 ; weight of, changed, 127 ; Table, Periodic System, 255-8; three kinds of rays of, 272 ; proportions of uranium and, in pitch- blende (see Pitchblende), 272 ; Table of Chemical Elements, 275 Rails, preparation of steel for (see Steel), 154 Rain, measure of fall (Dai- ton's experiments), 11 Ramsay (see Table), 274-5 Rayleigh (see Table), 274 Realgar (see Table), 281 Reaumur, scale of, 277 Red Lead (see also Lead and Minium, Table), 281 Red Phosphorus (see also Phosphorus), 191-2 Refrigerating Agents (see Calcium Chloride), 206 Reich (see Table), 274 Reichenstein, Tellurium dis- covered by, 126; Table, 275 "Reversibility" of Chemical Compounds, Theories of, 269 Rhodium (see Platinum), 161- 64; Table, 275 Richter, Table, 274 Rochelle Salts, 198-281 Rock Crystal (see Crystalline silica), 208 Rocks formed by shells, 204; (see Coquina) Rock Salt, deposits of, meat cured by, leather preserved by, 196 Rontgen Rays, discovery of, 271 Rose, Table, 275 Rosendale Cement (see Ce- ments), 205 Royal Society, 262 Ruby Glass, 210 Rubidium, discovery of, prop- erties of, 202; Table, 195, 275 Russia, Platinum ore found in, 161 Rust (see Ferric hydroxide), of iron, of zinc, of copper, 27 Rusting, cause of, 26 Ruthenium, description, 161 ; Platinum group includes, 164; Table, 275 Rutherford, Nitrogen discov- ered by, 39 ; Table, 275 S Safety Plugs (see Bismuth, uses of), 184 Salammoniac (see Table), 281; (Freezing Mixtures), 282 Saleratus (see Baking Soda), 198 Salt, Chemical Name of, 104; Glauber's, 125; chloride of magnesium in, 196; (see sodium chloride), 196; (see also Thermometer), 276; Table, 281; Metallic Salts (Acid Salt), 279; (see Salts) Saltpetre (see also Nitrate of potassium), 200-1; nitrogen part of, 35; Table, 281; Explosives, 282 Salts, Constituents of, 97; solubility of, distinguished as " neutral," 104 ; acid, 125, 279; basic, 279; Ep- som, 125; ferric and fer- rous, 155-6; metallic (see Table), 279; normal, 125; (see Table), 279; of lemon, 281; of potassium, 199; of tartar, Table, 281 Samirium (see Table), 275 Scandium, 258, 275 (Table) Sand (see Silicates), 208 Scheele, Chlorine first pre- pared by, 110 INDEX 305 Schmidt, Rays from thorium discovered by, 271 Schroder (see Table), 274 Science, its two divisions of development, 50 " Science Year Book," data from, 277 Scientific Practice, defined, 56-7 Sea, Mean temperature of (Thermometer), 276 Seaweed, Sodium carbonate prepared from, 197 Seidlitz, 198 Selenides, 116 Selenite (see Calcium sul- phate), 203 Selenium, group of elements includes, 108 ; sulphur group includes, 116; symbol of, 125 ; use of in elec- tricity, discovery of, atomic weight of, character of, two forms of, 126; (see also Table), 275 Sesqui (see Chemical Nomen- clature), 283 Silica, glucinum found with, 185 ; potassium combined with, 199 ; example of fam- ily of, 208 Silicates, 209 Silicon, group of elements in- cludes, 108 ; comparative importance of, 207; abund- ance of, 208-210; (see Peri- odic System, Table of), 255-8; Table, 277; carbide (see Carborundum), 209, 233; dioxide (see Quartz), 208; Table, 281. Silver, properties of, 135; specific gravity of, com- parative value of, propor- tions of purity of, effect of sulphur upon, ores of, mines of in U. S., 136; pro- cesses in mining, 136-7; oxidized, 136; alloys of, 139; Table of Alloys, 284; Table, 275; melting point of, Thermometer, 276; Con- ductivity of, Table, 279; (also see Table Per. Sys.), 255-8 ; bromide of, 113, 138 ; chloride of, 136, 138; ni- trate of, how formed, 137, 138; combinations of in photography, 138; use of, in electrical experiment (see Electrolysis), 234; (see also Lunar Caustic, Table), 281 Sirius, 271 Slaked Lime, making of, uses of, 205-6; Table, 281 Slate (see Silicate), 209 Smalt (see Cobalt), 157-8 Smith's, A., " General Inor- ganic Chemistry " (see Law of Atomic Weights), 250, 252 Snow (see Freezing Mix- tures), 282 Soaps, Carbonate of potas- sium used in making, 201 ; borax combined with, 207; yellow (see silicates), 209, 225 Soda, Caustic (see Sodium hydroxide), 197; Table, 281 Sodium, 30; proportion of in salt, 75; acids neutralized by, 103; hardness of, 130; description of, comparative weight of, symbol for, pro- portion in earth's crust, 195; apparatus for manu- facture of, 197; experi- ments of Sir H. Davy with, 266; (see also Tables), 255- 57, 277; Compounds, ex- pense of, 202; borate, uses and properties of, 199; car- bonate, 197, and Table, 281 ; chloride, 196; and Table, 281; Hydrate (see Caustic Soda, Table), 280; hydrox- ide, 197; (Natrium, Table), 275 ; nitrate, use of, in prep- aration nitric acid, 189 ; where found, 199; oxide, 306 INDEX peroxide, 197 ; potassium (see Rochelle Salt, Table), 281; salt, 207; silicates, 209; sulphate, 125; symbol for, 198; (see Glauber's Salt, Table), 280; thio-sul- phate, 125 ; use of, in pho- tography, 138 (see "hypo") ; tungstate (see Chromium), 183 Solder, 170; soft (see Alloys, Table), 284 Solids, most bases are, 103; total, in rain water, Table, 280 Solutions, early theory con- cerning, 238; modern dis- coveries in, 238-9 ; non-con- ducting and conducting, 240-1-2; Summary of theory of, 243, 253; ions and ca- tions in, 273 Sounding Balloon (see Bal- loon) Specific Gravity (see Table Per. Sys.), 255-258 Specific Heat, defined, 251; relation between atomic weight and, 252 ; reasons for law of, 253 ; Dulong and Petit's experiments, 206 Spectra, examination of, 271 Spectroscope (see Discovery of rubidium and caesium), 202; spectra studied by, 270-1 Speculum Metal (see Alloys), 284 Spelter, Table, 281 Spiegeleisen (see Manganese), 181 Spirit Alcohol (see Ethyl), 220 Spirits of Salt, Table, 281 Spirits of Hartshorn, Table, 281 Sprinklers, Automatic (see Bismuth), 184 Stable Compounds, explana- tion of, 230 Stalactites (see Limestone), 204 Stalagmites (see Limestone), 204 Starch, elements contained in, 87 Steel (see Iron), uses of, 144-5 ; preparation of, tem- pering of, colors indicating tempering, 149-50; qualities of, substances used for cooling, 150-1 ; effect of various elements upon, Bes- semer process of manufac- ture, 151-2 ; magnetization of, 154; melting point of, Thermometer, 276 Steel Age, 144 Stereo Chemistry, 226; (see also Table of Alloys), 284 Stone Age, tools and weapons of, 139, 144 Stromeyer, Table, 274 Strontium, use in paints, 184-5 ; resemblance to cal- cium, 185; calcium grouped with, 203; discovery of, 266-7 ; Tables, 275-277 ; Compounds of, 184-5; hy- droxide, use of, 184-5; nitrate, use of, 185 Sublimation, 189 Sugar of Lead, Table, 281 Sulphates, of Aluminium and potassium, 280; of cal- cium, 125; ferric (see Fer- ric Salts), 156; of iron (see Copperas, Table), 280; of Mercury (see Mercury, Ta- ble), 281; of potassium, 201 ; crystallized s. of soda (see Freezing Mixtures, Table), 282; zinc, 125 " Sulphides," 118 ; copper, iron s., how produced, 93; lead s. (see Galena), 167 Sulphur, group of elements includes, 108; elements in S., group, 116; extraction of, from ore, artificial pro- duction of, existence of, in INDEX 307 food products, in animal bodies, 117; mercury com- bined with, properties of, lead combined with, defined as non-metal, allotropic, ef- fect of heat .upon, 117, 118, 119; form of, soluble in alcohol and ether, 120; use of in electric machine, ef- fect of friction upon, six different sorts of, insoluble form of, crystals of, 120-1 ; atomic weight of, uses of, flowers of, symbol for, col- loidal form of, amorphous, 121; affinity of silver for, 136, frequency of, in or- ganic compounds, 217; (see also Tables), 255-7, 277; (Thermometer), 276; Ex- plosives), 282; compounds of, where found, 117 ; with barium, use of, 185; diox- ide, uses of, 123; with hydrogen, 122 ; with potas- sium, 182 ; with strontium, uses of, 185 Sulphuric Acid (Oil of Vit- riol), in extraction of bromine, 112; formula for, 123; two classes of salts formed by, important uses of, importance of sulphates formed by, 124-5; use of in preparation nitric acid, 189; use in preparation of ethers, 222 ; decomposition of (see Electrolysis), 236; (see Tables), 281; (Explos- ives), 283 Sulphuric Ether, 282; (see Freezing Mixtures), 282 Sun, 271 Talc (see Silicates), 209 Tannin, iron salts combined with, 156 Tantalum (see Table), 275 Tartar Emetic (see Table of Common Names), 224, 281 Tartaric Acid (see Organic Acids), 223 Tellurides, 116 Tellurium, group of elements includes, 108 ; sulphur group includes, 116; atomic weight of, symbol for, de- scription of, discovery of, 126; Table, 275 Temperatures, methods of producing extreme, 232 Tennant (see Table), 275 Terbium (see Table), 275 Terra Alba, use of gypsum in, 206 Thallium, Table, 275 Theory, scientific definition of, 56 Thermit, temperature at- tained by, Thermometer, 276; (see also Alumino- thermics), 180 Thermometer, 276 Thermopyles (see Bismuth), 184 Thomson, 265 Thorium, Rays of, discov- ered (see Schmidt), 271 Thulium, Table, 275 Tin, atomic weight of, 127; symbol for, characteristics of, foil, 169-70; use of, in alloys, 170 (see also Table of Alloys), 284; point of fusion of, Thermometer, 276; Tables, 275-9; bi-sul- phide of (see Mosaic Gold, Table), 281 Titanium, Tables, 275-7 Travers, Table, 274-5 Tri (prefix) (see Chemical Nomenclature), 283 Tungsten (see Chromium), 183; Table, 275 Turquoise ( see Aluminium Phosphate), 178 Type Metal (see Table of Alloys), 284 308 INDEX Um (termination") (see Chemi- cal Nomenclature), 283 "Universal Solvent," 9 United States, silver product in, 136; iron plentiful in, 146; lead product in, 167 Universal Matter, Robert Boyle's theory of, 10 Uranium (see Chromium), 183 ; comparative weight of, 183; rays of, discov- ered, 271; proportions of, and radium in pitchblende, 272; (see Table), 275 Urea, first artificial prepara- tion of, 216-7; (see Solu- tions, discoveries concern- ing), 240 Valences, terminology of, de- fined (footnote), 214 Valency, variation of ele- ments in, 213; units of, adjectives of, 256; theory of, 268; (see also Table of Periodic System), 254-6 Valentine (see Table), 274 Vandium (see Table), 274 Vapor, Aqueous, Volume of, in normal air, Table, 278 Vauquelin (see Table), 274 Verdigris (see Copper ace- tate), 142; Table, 281 Vermilion (see Pigment of cinnabar), 119; (see also Two forms of cinnabar), 171; Table, 281 Vitriol, blue, green, white, oil of, 281 ; uses of green (see Ferrous Salts), 155-6 Vinegar, formation of verdi- gris by copper and, 142; wine turns into vi (see Or- ganic Acids), 223 Volatile Alkali (see Table), 281 Volta, electric battery of, 234 W "Washing Soda" (see So- dium carbonate), 197; uses of, 198 Water, early beliefs concern- ing, 9; separation into gases, 12, 15; chemical composition of hydrogen and oxygen, 40; true na- ture of w. discovered, 41 ; action of, chemically and physically, 42, 45; sub- stances deprived of, 46; chemically an acid, 101 ; dissolution of salt by, f96; affinity of calcium chloride for, 206; application of Avogadro's Law to, 250; composition of discovered, 264; experiments of Davy with, 267; freezing point of, boiling point of (Ther- mometer), 276; density of, expansion of, rel. weight of, composition of rain, Table, 282; (see also Ta- ble), 277; (Freezing Mix- tures), 282 Watery Vapor, as contained in air, 19 Wax, use of in etching, 190 Waxes, ethers used to dis- solve, 222 Welsbach (see Table), 275 White Heat, degree of (Ther- mometer), 276 White Lead, processes for preparation of, description of, 169 White Wash (see Calcium hydroxide), 205 White Vitriol, 125 Wine (see Organic Acids), 223 Winkler (see Table), 274 Williams, Dr. Henry Smith, demonstration of, concern- ing atomic theory, 266 Wohler, aluminium first ob- tained by, 175-6; urea ar- INDEX 309 tificially prepared by, 21G-7, 225, 267, 269 ; Table, 274 Wollaston, Dr., demonstra- tions of, 265; Table, 275 Wood, burned by nitric acid (see Nitric Acid), 190 Wood Alcohol (see Methyl Alcohol), 220 Wrought Iron (see Iron), 148 X X-Rays (see Rontgen Rays), 271 Xenons (see Halogens), 109, 256, 278; (Tables) Yellow Phosphorus (see Phos- phorus), 191-2 Yellow Pigment (see Chromes) , 183 Z Zero, Absolute (Thermome- ter), 276 Zinc (Spelter), description of, general uses of, effect of air upon, elements in ores of, extraction of, from ores, use of, in electric batteries, 172; symbol of, 173; (see Tables), 275, 279, 281 ; proportions of, in al- loys (see Table of Alloys), 284; Chloride of, how pro- duced, 93-4, 173; oxide of, 173 ; sulphate, 125 ; uses of, 173; (see White Vitriol, Table), 281 Zisconium (see Table), 275 THIS BOOK IS DUE ON THE LAST DATE STAMPED BELOW AN INITIAL FINE OF 25 CENTS WILL BE ASSESSED FOR FAILURE TO RETURN THIS BOOK ON THE DATE DUE. 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