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Chemistry

( Originally Published Early 1900's )

No story in all the "Arabian Nights," in all the transformations of mystic spell or fairy wand, is half so wonderful as the history of chemistry for the past one hundred years. We read of Cinderella's godmother and the white mice she transformed into milk-white steeds for a fairy coach scooped out of a pumpkin, but this pales into paltry insignificance by contrast with the miracles of modern science. Alchemy of old sought the transmutation of the metals. Chemistry of to-day turns stones into bread. The foolish alchemists spent centuries of unceasing toil in vain search for the elixir of life. The wise chemists take lifeless clods of earth, and from them evolve myriad things to delight the eye and to tickle the palate. We ridicule and pity alchemists in their attempts to turn mercury into gold, forgetting that our own chemists wrought infinitely greater magic when they discovered the process whereby at will they could extract from foul, filthy coal tar all the colors of the rainbow, and all the sweet perfumes of Araby the Blest. Modern chemistry, chafing under the restriction of the laboratory, has gone forth into the highways and hedges 0f industry, working magic all along its course. There is no art and no manufacture, however insignificant, that has not come under its beneficent influence to a greater or less extent.

With due consideration for the important and essential attainments of the period immediately preceding, the Nineteenth Century may justly claim the science of modern chemistry as its own. Of course, as far back as history goes certain chemical facts have been known and various phenomena observed and treated of, and only by the gradual collection and explanation of such facts has the broad science of to-day been made possible. Among the nations of antiquity the Egyptians appear to have possessed greatest chemical knowledge; they smelted ores, dyed stuffs, colored glass and preserved the human body from decay. They were also familiar with medicines and pigments, soap, beer, vinegar, common salt, vitrol, enamel, tiles and earthenware. The Chinese also early became acquainted with the preparation of metallic alloys, processes for dyeing and for the making of gunpowder, niter, borax, sulphur, porcelain and paper. The Greeks and Romans derived what chemical knowledge they had from the Egyptians and the Phoenicians, but they added little or nothing to the science. Aristotle, however, advanced a theory which for Centuries exerted a great influence in the pursuit of the study. He recognized four elementary conditions of matter fire, air, earth and water. The Arabs, when they overran Egypt in the Seventh Century, imbibed much of this knowledge, which, as a black art, they carried with them into Spain. It then became known as alchemy, the chief aim of which was to transmute the metals and the discovery of the philosopher's stone, the touch of which would convert mercury into gold, and at a later period regarded as curing all diseases. The importance of the Arabs as chemists ceased with the Twelfth Century, but their charlatanry was carried on more or less by the European alchemists until the latter part of the Seventeenth Century, when the first germs of the real science began to appear in the phlogistic theory of Stahl and the speculations of Becher.

In 1718 Geoffry brought out the first table of affinities, and in 1832 the chemical relation of heat and light were demonstrated by Boerhaave. In 1754-1759 Marggraf added alumina and magnesia to the then known earths lime and silica. He also extracted sugar from plants, and about the same time Macquer, of Paris, pointed out the existence of arsenic acid. Hales, in 1724, and Black of Edinburgh, in 1756, made important discoveries regarding air and aeriform bodies, showing that carbonic acid evolved during fermentation, respiration, and by the action of acids on chalk, was different from atmospheric air. About 1770 Priestley began to announce a number of important discoveries, among them oxygen, and the ammoniacal, hydrochloric, and sulphrous acid gases. Scheele contributed, in 1773-1786, chlorine, hydrofluoric, prussic, tartaric and gallic acids, also phosphoric acid from bones. During the same period, Bergman and Cavendish were experimenting with gases to the knowledge of which they materially added. Between 1770 and 1794 Lavoisier reorganized nearly all of the then known science, and the system he founded formed a skeleton which the chemists of the succeeding Century adopted. In 1787 Berthollet advanced some important doctrines in regard to affinities, and made some valuable discoveries in chlorine. Advanced organic chemistry received an impetus from the researches of Fourcroy and Vauquelin. Mineral chemistry received contributions from Klaproth, and the doctrine of combining proportions was promulgated by Richter.

Thus the entire Eighteenth Century may be said to have been occupied in organizing into the semblance of legitimate science the dismembered and scattered portions of knowledge that had been accruing from remote antiquity down through all the ages of civilization, and in rejecting and disproving many false doctrines that had so long obtained.

At the very dawn of the Nineteenth Century the horizon of chemistry widened immeasurably, and in it shone that brilliant galaxy which included the great Berzelius, Gay-Lussac, Thenard, Brand, Dalton and Sir Humphrey Davy. In fact, during the early years of the Century chemistry was the science which more than any other engrossed men's minds. An international rivalry for priority took place between Berzelius, the Swede, Davy, the Cornishman, and Gay-Lussac, the French savant: An incalculable impetus was given the scientific movement by the establishment of various periodicals devoted especially to the publication and criticism of new discoveries. The Royal Society and the Institute of France inaugurated the custom of employing many of the great chemists of the day as lecturers. The enthusiasm that ensued was boundless.

Among the first of the notable attainments of these early years was the perfection by Dalton (1766-1844) of Richter's doctrine of combining proportions. Dalton was led to the formation of his atomic theory in 1808, by the observation that when a determined quantity of any sub-stance unites with different quantities of another sub-stance, the quantities of the second substance always bear a simple relation of weight to each other. The elements Dalton regarded as composed 0f homogeneous atoms, each different element having its own specific weight. He also discovered the law of multiple proportions, and that the atomic weight of compounds is the sum of the atomic weights of their constituents. Dalton's theories were at once admitted into the science, and formed the basis of innumerable succeeding discoveries. The expansion of gases, the relations of mixed gases, elasticity of steam and evaporation were also the subjects of Dalton's experiments, which were at a later date diffused and extended by Wollaston (1767-1829). In 1812 Brand founded the Society for the Improvement of Animal Chemistry, with a view of extending that branch of the science known as physiological chemistry. Here was an entirely new departure.

Most intimately connected with Dalton's atomic theory was the discovery by Gay-Lussac of the law of combining volumes, in accordance with which gases unite with each other. He proved conclusively that chemical compounds are formed only in a few fixed and definite proportions. He observed that one volume of oxygen when combined with two volumes of hydrogen unites in the form of water, A large proportion of Gay Lussac's researches were in the field of organic chemistry. His investigation of the cyanogen compounds gave rise to the idea of organic radicals. The first really useful apparatus for the analysis of organic substances was invented by him. The system for determining the specific gravity of the vapors of sub-stances, with a view of controlling their analysis, was also Gay-Lussac's idea. His applications of chemistry to the arts were of great importance, and his methods of assaying silver and gunpowder are still in use.

The debt which practical chemistry owes to Sir Humphrey Davy is incalculable. In his lectures before the Royal Society and the Institute of France, in 1816, he especially emphasized the importance of the connection between science and industry. He was the first to suggest the application of chemistry to agriculture. The most notable of Davy's researches were in electro-chemistry. At the same time that Dalton was working on his atomic theory, Davy discovered two new elements, sodium and potassium, the result of decomposing soda and potash by the electric current. By the same method he also succeeded in separating metals from the fixed alkalies, potash and soda, proving them to be metallic oxides. He disproved the doctrine of Lavoisier, so long dominant, that all acids must contain oxygen. The idea of hydrogen acids was thus introduced, and substances which contain no acids admitted to be salts. Davy's researches upon flame and combustion were especially valuable, leading ultimately to the discovery of the safety lamp.

Thenard (1777-1857) contributed a vast amount of knowledge to the science. His division of the metals into groups, according to their peculiarities at different temperatures in the presence of water, was an important experiment. To him, also, is due the discovery of the peroxide and the persulphide of hydrogen, of boron, hydrofluoric acid and fluoride of boron.

Modern chemistry, in all its branches, probably owes a greater debt to Berzelius (1779-1848) than to any other one man. The fruit of his labors is scattered throughout the entire domain of the science. No chemist has deter-mined by direct experiment the composition of a greater number of substances nor has anyone exerted a greater influence in extending the use of analytical chemistry. In conjunction with Hisinger he obtained the remarkable amalgam which mercury forms with what is supposed to be ammonium. He was the first to use hydrofluoric acid in the decomposing of minerals and chlorine in their analysis. One of the principle services he rendered was the development of the present theory of the science, and the introduction of an admirable system of chemical symbols, which obtained exclusively until 1832. In that year Dumas, supported by the French school of chemists, opposed the binary system of Berzelius, and substituted one which carried out Dalton's atomic theory to its logical extent. With the new system chemistry assumed a still more systematic aspect.

Like Davy, Faraday (1791-1867) devoted most of his researches to developing the relations of electricity to chemistry. He extended the idea originally suggested y Davy regarding the identity of electricity and chemical affinity, both being but different expressions of one and the same force. His discovery of benzine and his work upon the liquefaction of chlorine and other gases and upon various compounds of carbon and chlorine, and of ammonia and metallic chlorides, have proved invaluable to the science.

The doctrine of isomerism, which was originated by Faraday, was taken up and promulgated by Mitscherlich, of Berlin (1794-1863), who discovered the laws of isomorphism and diomorphism, in accordance with which the crystalline forms of certain substances are governed.

Wohler's classic synthesis of urea in 1828, hitherto known only as an animal product, marked the beginning of advanced synthetical chemistry. A great and revolutionary epoch in the history of the science then began. The barrier between organic and inorganic bodies was at last broken down, and the domain of practical chemistry immeasurably extended. The mere catalogue of what has been done in organic synthesis would fill a volume. Immediately following Wohler's discovery, Berzelius, Liebig, Dumas, Laurant, Hofmann, Cahours, Frankland and a host of others especially devoted themselves to the doctrine of substitution, and the result was a vast number of new compounds to which further investigations are constantly adding. Since then alcohol, grape sugar, acetic acid, various essential oils, similar to those of the pear, pineapple, etc., have been formed by combining oxygen, hydrogen and carbonic acid.

The highly complex constitution of various organic products, albumen, fat, gums, resins, acids, oils, ethers, etc., is the subject of organic chemistry, the study of which has, within recent years, led to some of the most marvelous and popular discoveries of the age. Coal tar, the waste product of the gas retort, has proved one of the great bases for synthetical work. Perkin, in 1858, patented a dye-stuff, aniline violet, and that dye marks the beginning of an enormous chemical industry the production of the coal-tar colors.

The natural coloring materials, which previously had been the sole resource of the industry and which were found generally in their natural state in the vegetable kingdom, were in time supplanted by artificial dyes, converted from the unpromising black fluid. The first obstacle in the way of popularizing the coal-tar colors was the great expense of their production, in consequence of the small quantities in which the matter, alizarine, is found. Mitscherlich discovered that by acting upon benzine with nitric and sulphuric acids for the production of nitro-benzole he could produce a compound from which aniline might be obtained in large quantities. This change is analogeous to that of glycerine into nitro-glycerine, but the nitro-benzole is not explosive. It is an oily liquid with the delightful odor of almonds, and is used extensively in perfumery under the name of essence of mirbane.

By the action of reducing agents the oxygen of the nitro-benzole is replaced by hydrogen, and the result is aniline. The differentiation of color and the many shades and gradations of colors are due to chemical reactions caused by the presence of various acids and bases in the crude aniline oil. Aniline red, or magenta, was one of the first colors discovered, and the furor it created upon its first appearance in the world of fashion is yet vivid in the recollection of many people. The coloring matter used to produce this shade is a salt of a base known as rosaniline, which is formed from aniline oil by a process of oxidation. The oxidizing agent most commonly used is arsenic acid, whose poisonous nature renders it somewhat unsuitable for this purpose, and there have been frequent cases of poisoning attributed to the wearing of garments dyed with this substance. Taking rosaniline as a basis, most of the other colors are prepared by the action upon it of various chemical reagents. By the action of bichromate of potash and sulphuric acid upon rosaniline aniline, violet is obtained, and aniline blue is formed by heating rosaniline and aniline oil together and treating the combined product with hydrochloric acid. The greens are formed by the addition of sulphur, and yellow by the action of nitrous acid upon an alcoholic solution of rosaniline. Aniline black is in reality a very deep green, formed by the action of oxidizing agents upon aniline oil. The bases producing these various dyes have in turn complicated reactions of their own which produce the shades and variations of colors almost to infinity. Practically about a ton and a half of coal is required to make a pound of rosaniline, but that amount possesses coloring power sufficient to dye two hundred pounds of wool.

Besides coloring matter the chemist has made, coal tar also produces carbolic acid, one of the most powerful antiseptic agents evolved by modern chemistry. Some useful dyes are also obtained from it. Its immediate source is that portion of the distillate known as the light oils, to secure which the tar oil is subjected to a treatment of caustic soda, and the mixture violently shaken. As a result the caustic soda dissolves out the carbolic acid and the undissolved oils collect on the surface, from which they can be skimmed off from the alkiline solution underneath. Neutralization of the soda in the solution takes place with the addition of sulphuric acid, and the salt thus formed sinks, while the carbolic acid rises to the surface. So powerful is this acid when refined and purified that one part in five thousand parts of any decomposible animal or vegetable matter will for months prevent putrefaction.

Through the rapid and steady advance 0f synthetic chemistry in recent years the day seems not far distant when all the food now grown by nature will be prepared by chemical processes. For many years past synthetic chemistry has had an eager and jealous eye upon food .making. It has progressed so far already that several great agricultural industries have been impaired by its advancement. Compounds and products that were once obtained solely by plant growth in the fields are now entirely furnished by the chemical laboratory and by direct manufacture.

The manufacture of oleomargarine is one of the most familiar examples of what synthetic chemistry has done in food making. The attempt to secure a substitute for but-ter was undertaken in 1869, by Mege-Mouries, at the instigation of the French Government, the purpose being to secure a cheap product that might be used by the navy and by the poorer classes. The principal points in Mege-Mouries' patent were the preparation of margarine oil by the artificial digestion of fat taken from animals, and the separation of the stearine, which melts at a high temperature by pressure. The conglomeration so produced was then churned into milk, the emulsion being facilitated by the addition of cow's udder and carbonate of sodium. The result of the process was a compound which, when salted and colored, not only bore a close resemblance to the genuine article, but had almost the same taste and general properties. Later modifications, of this process have greatly simplified the making of oleomargarine, as it has come to be called. Cotton seed oil was found to be a valuable adjunct to its composition, and numerous improvements have been patented for purifying the animal fats by fermentation and by the subsequent use of chemicals. For cooking purposes the oleomargarine has proved a substitute for butter, but as yet it is impossible for the sentimental epicure to accept it for eating purposes in place of butter, as he claims that there is absent that peculiar flavor and aroma of the milk product. Laying aside all sentimental prejudices, however, it has proved a veritable boon to the poorer classes, and so perfect has its similitude to the natural article become that stringent laws have been passed in many states of this country and in Europe, with reference to its manufacture and sale. In spite of legislation, however, the manufacture has steadily increased, and the United States alone produced 42,534,559 pounds in the year 1896-1897.

In the department of synthetic chemistry, the very recent experiments of Berthelot, of Paris, have been most marvelous. He has succeeded in so recombining the fat acids with glycerine as to produce the original fats, and he has also caused all the more common mineral and organic acids to unite with glycerine in a manner precisely analogous. In fact, Berthelot has been called the foster-father of synthetic chemistry. To clearly conceive of the impending changes which seem to be made possible by Berthelot's researches, it must be remembered that milk, eggs, flour, meat and indeed all the edibles, consist almost entirely (the percentage of other elements being very small) of carbon, hydrogen, oxygen and nitrogen. Berthelot has proved conclusively that it is possible to produce anything from eggs to beefsteak in the laboratory. The form will be different, but it will be the same identical food, chemically, digestively and nutritively speaking. To quote Professor Berthelot in regard to his revolutionary discoveries :

"One must consider the long evolution which has characterized the development of foods and the major part which chemistry has played therein. The point is that from the earliest time we have steadily increased our reliance upon chemistry in food production, and just as steadily diminished our reliance upon nature. Primitive man ate food and vegetables raw. When he began to cook, when he first used fire, chemistry made its first intrusion upon the sphere of nature. Today the fire in the open air has been replaced by the kitchen. Every cooking utensil now used represents some one of the chemical arts. Stoves, sauce pans and pottery are the results of chemical industries. So also modern cookery uses an infinite number of compounds food compounds which, like sugar, for instance, have been subjected to a more or less complex chemical treatment in their journey from the field, in which they grew, to the kitchen, in which they are used. The ultimate result is clear. Chemistry has furnished the utensils, it has prepared the foods, and now it only remains for chemistry to make the foods them-selves, which, indeed, it has already begun to do."

Artificial eggs have already been produced by synthetic process, and sugars have recently been made in the laboratory. Commerce has taken up the question and a recent invention has been patented by which sugar can be manufactured on a commercial scale, by the combination of two gases, at a cost of something like one cent per pound. As the matter appears at present there is no logical reason why the synthetical manufacture of sugar should not become in time as important an industry as the making of oleo-margarine.

There is also a possibility that in time coal-tar may pro-duce sugar as well as carbolic acid and dye-stuffs. Both saccharine and dulcine (either one of which is more than 200 times as sweet as sugar) have been obtained from that foul-looking product. The chemists have made several kinds of sugars that are not known in nature at all. Most of them are not fermentable, and for that reason are not digestible. Glucose, though not a synthetic product, is nevertheless the product of certain chemical actions. It is obtained alike from the starch of corn and potatoes, the starch being beaten to a cream and treated to sulphuric acid and marble dust. Tea and coffee are now made artificially in the laboratory, and if occasion demanded they could be produced in commercial quantities. The essential principle of both stimulants is the same. They are chemically identical in their constitution, and their essence has often been made synthetically. Chemists have succeeded in synthetically producing oil of mustard, which physicians prefer to the natural product, owing to its greater purity. They have also manufactured tartaric acid, turpentine and conine. This last is the poisonous principle of the hem-lock, and is almost the same as nicotine, the essential principle of tobacco. It is thought practicable to convert it into nicotine, and when this is accomplished any sort of leaves may be impregnated with the mixture and with certain flavoring oils, and will doubtless serve as an excellent substitute for tobacco. The chemists are now able to counterfeit lactic acid, which is the sour principle of sour milk. They also make citric acid, which is the sour of the lemon. A recent achievement of considerable importance is the manufacture of salicylic acid from carbolic acid. In nature it is obtained from the wintergreen plant and from certain varieties of the willow, and it was formerly very costly. It is now made by the ton and is extremely cheap. Artificial milk is a hope of the very near future, as are also edible fats, and meats of all varieties.

The production of artificial musk from coal-tar is a wonderful triumph of synthetic chemistry. It is likely to drive the real article out of the market before long. The perfumes of nearly all the odorous flowers, due to ethereal oils, are now produced artificially, and so perfect is the similitude to the scent of the real perfume that it is impossible to detect the difference. Attar of roses is not yet produced, but it is in sight. The thereal oil that gives the rose its peculiar odor is called "rhodonol," and the same oil is found in lemon grass and in geraniums. The ethereal oils which give to fruits their delicious flavors are all counterfeited easily, inasmuch as they are very simple chemical compounds. Already the chemists are manufacturing oil of banana, oil of raspberry, oil of pineapple, oil of pear and many others. Oil of bitter almonds has also been counterfeited, and though chemically different, it has the same flavor as the real. The methods of manufacturing brandy and liquors from alcohol and the essential oils are so familiar that they need not be commented on.

Without occupying themselves with the investigation of the transmutation of metals, chemists have ceased to ridicule the aspirations of the alchemists, although they condemn the venal spirit which actuated them. The possibility of realizing the dreams of the old philosophers has of late, however, been strongly suggested by the discovery of several remarkable examples of allotropism a term employed to signify that the same body may exist under two or more different conditions, possessing distinct physical and chemical properties. For a long time it had been known that diamond, charcoal and graphite are, chemically speaking, identical, but the fact attracted little attention. The discovery of ozone (allotropic oxygen) by Schönbein, of Basel, and of red phosphorus by Schrötter, of Vienna, have set the chemists to thinking, and to experimenting.

In 1897 E. Moyat discovered a process of making diamonds very small, it is true, but nevertheless real stones, not imitations. Pulverized coal, iron chips and liquid carbonic acid were placed in a steel tube and hermetically sealed. The contents were then subjected to the action of an electric current by means of two electrodes introduced into the tube. The iron becoming liquified, was saturated by the pulverized coal, and the carbonic acid evaporated, thereby creating an enormous pressure on the iron and coal. This pressure increases the dissolution of the coal in the liquid iron. While the mixture is cooling, crystallization of the carbon takes place, partly in the form of real diamonds and partly in the form of crystals. The conglomeration is segregated by dissolving the iron in muriatic acid, and the morsels of pure diamonds are extracted.

In 1888 two French chemists, Frémy and Verneuil, produced rubies precisely similar in color and chemical composition to the natural stones, and of a size sufficiently large to be set in jewelry. It being known that the natural ruby is simply crystallized corundum, or oxide of aluminum, with a trace of coloring matter chromium, all that remained for the Frenchmen to do was to treat ordinary alumina, containing a little bichromate of potash, with certain fluorides. The mixture was placed in a crucible that was kept constantly heated for one week at a temperature of 2,400 degrees Fahrenheit. After the completion of the process the rubies adhere to the sides of the crucible. The largest rubies thus far obtained weigh one-third of a karat. Their crystalline form, hardness and physical characteristics are in every respect identical with the natural stone.

Not content with usurping nature's duties in the production of food and gems, chemistry has also undertaken the manufacture of ice, for which a number of processes have been devised. The permanent gases, such as hydrogen, or the compound gases, as the air, are forms of matter which, if subjected to sufficient pressure and cold, become condensed and liquid. At a temperature of 212 Fahrenheit steam condenses into water, while ammonia boils at 28 1/2 degrees. By subjecting ammonia to pressure its boiling point is raised in proportion to the pressure. Hence, by taking ammonia gas and subjecting it to pressure sufficient to raise the temperature to a high degree, and by pouring cold water on the vessel containing the ammonia, the latter will become liquified. Removing the pressure and allowing the liquified ammonia to expand, the temperature falls very rapidly, and as much heat is lost as was added to it by compression. Numerous inventions, based upon this principle, are now in use for the commercial production of ice. The process most widely employed, however, is that of the expansion of compressed gas, or of vapor cooled under its compression.

The development of that branch of practical chemistry termed analysis, and its special application to the detection of food adulteration is probably of more importance to humanity than the triumphs of synthesis. The chemist is now able to determine definitely and exactly the ingredients of baking powders, flours, wines and liquors, spices, confections, and indeed, any article of food where there is the slightest possibility of fraudulent substitution. Were it not for the powers of analysis there would be no protection whatever against the impositions of synthesis.

In all branches of analytical chemistry constant improvement has been effected. Gas analysis was perfected by Bunsen (1863-'70). The chemist's balance has been improved by the labors of Becker. New methods of attack have been applied. By the electric furnace M. Moissan was enabled, in 1897, to isolate fluorine, which resisted isolation for so many decades. By the utilization of the electric current rare metallic elements have been reduced from their compounds. So perfect are the processes for the analysis of the metals that the practical assayer does not consider seventy-five determinations an unusual day's work. By a chemical analysis of sea water, Professor Liverside, of Australia, in 1896, discovered that it contains from one-half to one grain of gold per ton, or from 130 to 260 tons per cubic mile, making a total of about 50,000,000,000 tons for all the oceans of the world. He also found the same sea water to contain from one to two grains of silver per ton, the gold existing as a chloride and the silver as a nitrate.

The influence of chemistry upon the industries and the arts has been incalculable. The perfection attained in the manufacture of glass, pottery, tiles and bricks presents a striking instance in chemical technology. Although glass of a more or less inferior quality had been made since time immemorial, not until in comparatively recent years has it been produced so cheaply as to come into universal use. For many hundred years it was an article of luxury only, and a heavy tax was placed upon it. Now the poorest person may use on his table, every day, glassware more beautifull than a king could buy not many years ago. Chemically glass is a silicate, or a compound of silicic acid and various bases. It is formed by fusing common sand with the carbonates of the alkalies or with the metallic oxides. Until the nature and properties of the different earths had become thoroughly understood by the chemists, glass-making was a precarious and uncertain undertaking. The product happened to be clear or dark, hard or brittle in accordance with the nature of the elements composing it. By chemical analysis glass-makers are now able to deter-mine just what sand is best suited to the manufacture of each variety of glass. Ordinary window glass is a silicate of lime and soda, and if silicate of potassium is added plate glass is produced. Flint glass is a silicate of potassium and lead. The effect of the lead is to give increased brilliancy, and renders it soft and easily cut. A mere trace of iron in the sand will render the glass dark. Water-glass is an alkaline silicate. It is readily soluble in water and is largely used in the arts. To obtain the great refractive power necessary for lenses and prisms, a large percentage of lead is used. Colored glasses are produced by the chemical action of various metallic oxides which have been added to the molten materials. The colors produced are found to vary with the degree of heat employed. All the colors of the spectrum may be obtained from oxide of iron; the oxides of cobalt and copper produce the various shades of blue; oxide of gold, ruby red; oxide of manganese , amethyst; a mixture of copper and iron ore, emerald green; and oxide of uranium, topaz.

The progress of the pottery and brickmaking industries has been no less phenomenal in the past hundred years. The making of china is one of the fine arts of the age, and like the manufacture of glass it has been developed entirely by the application of chemistry. The same might be said of brick-making, in which. numerous improved processes have appeared. One of the most notable and recent of these is the Chambers brick machine, patented in 1887, which has a capacity of 50,000 bricks per day at a cost from the clay bank to the shed of only 77 1/4 cents per thousand.

The utilization of waste is one of the most remarkable functions of modern chemistry. It is in this that science shows her truest advance in the recognition and preservation of trifles, and in seeing them in the importance of their true relation. One of the most marvelous conquests over waste was the conversion of coal tar to commercial purposes, as has already been mentioned. Chemistry allows practically nothing to be wasted now. Cotton seed, long the pest of the Southern plantation, is now being converted into oil, fertilizer and fuel. Sawdust and shavings, looked upon for centuries as absolutely useless, are now mixed with refuse mineral products and pressed into bricks, which are light, impervious to water and absolutely fire-proof. Formerly one-seventh of the coal mined was crumbled so fine in removing it from the mine that it was useless. This is now mixed with pitch and made into bricks that burn with an intense heat and leave no ashes. The skins and intestines of cattle are transformed into the well-known and exceedingly useful substance, gelatine, which is the same as ordinary glue, differing from it only in purity. Common glue is prepared from the trimmings of hides, and the refuse of slaughter houses and tanneries. Gelatine unites with tannin to form an insoluble compound. This reaction is the basis of the tanning process by which raw hides are converted into leather. Sludge acid, one of the most offensive wastes known to man, has been made to produce a most valuable oil. Carbonic acid gas given at breweries and distilleries during fermentation, has been an enormous waste. By a process recently patented it is all now collected and liquefied for commercial purposes. Slag, the refuse of the puddling furnace, has proved invaluable in the manufacture of paint, containing as it does 55 to 70 per cent of pure oxide. The chips of the marble cathedral on Fifth Avenue, New York, supplied 25,000,000 gallons of soda water, which is itself a concoction made possible by modern chemistry. The prominent ingredients in a glass of soda water are marble dust and sulphuric acid, neither of which is regarded as healthful or palatable when taken separately, but by the magical art of the chemist they unite in the formation of a delicious beverage.

A good indication of the progress that is still being made in chemistry is the constant discovery of new elements. Most of these discoveries since 1860 have been made by the spectroscope, an instrument constructed by Bunsen in 1859 for chemical research, based on the use of the prism. In 1860 Bunsen discovered rubidium and cesium; Crookes, in 1862, discovered thallium; Reich and Richter, in 1863, indium; Boisbaudran, in 1879, samarium; and in the same year Nilson, scandium, and Cleve, thulium; Welsbach, in 1885, neodymium and praseodymium; Marignac, in 1886, gadolinium; Winkler, in 1886, germanium; Ramsay and Rayleigh, in 1894, argon; Ram-say, 1888 to 1895, helium.

In 1896 a new determination of the relative weights of hydrogen and oxygen was made with more than ordinary care, and the result is that the atom of oxygen is 15.869 times heavier than the atom of hydrogen. In the same year a new element, to which the name of lucium has been given, was discovered.

In 1898 chemical science was enriched by the discovery of three, perhaps four, new elements in the atmosphere. On June 9, 1898, Ramsay and Travers discovered krypton, and a short time afterward, neon and metargon. Krypton is described as an element heavier than argon, and less volatile than oxygen or nitrogen; neon, as its Greek derivation suggests, is an entirely new and unfamiliar element; and metargon is closely allied to argon. The fourth discovery is aetherion, a new aerial gas detected by Professor Brush. Its density is only 1/10,000 of that of oxygen and it has been conjectured that it may extend indefinitely into space. Ozone has been liquefied, and the result is a fluid of indigo-blue color. This is very remarkable, considering that liquid oxygen, of which it is but a modified form, is colorless. The density and boiling point of liquid hydrogen was determined in 1898 through the agency of a platinum resistance thermometer, and helium, one of the most stubborn of elements, was liquefied by Professor Dewar, of England, in the same year.

After a thoughtful consideration of the remarkable achievements of the present Century, it may seem to the laity that the limit of chemical research has almost been reached. But the chemist knows that his work is not done; in fact, it is but commenced. There is an infinity of problems yet to be solved by the chemists of the future.

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