 CHAPTER 20 SUGAR AND STARCH Chemistry is an all-pervading science. Its scope is not confined to the laboratory or the chemical factory. There is chemistry of daily life as well as chemistry of the stars, a chemistry of foods as well as a chemistry of fire. We have already seen that many common phenomena really depend on the operation of chemical principles, and chemistry has a good deal to say also about our food and the changes which it undergoes. Sugar and starch are two of the main components of our food and belong at the same time to an interesting class of chemical compounds known as carbohydrates. Each member of this class contains the elements carbon, hydrogen, and oxygen, and the characteristic feature to which reference is made in the part hydrate of the word carbohydrate is that the proportions of the hydrogen and oxygen are the same as in water. The constituents of our food belong to one or other of the three classes, carbohydrates, fats, and proteates or albuminoids. The last mentioned include all the nitrogenous products, a certain proportion of which is essential to the health of the body. Most ordinary foodstuffs do not belong exclusively to one class, but are mixtures. Wheatmeal, for instance, contains 9% of proteates, 1% of fats, and 74% of carbohydrates, mostly starch. In addition, there is about 15% of water and a little mineral ash. As another example of a common food, we may take potatoes, which contain 75% of water, 21% of carbohydrates, and 22% of proteates. They contain only a trace of fat. The P differs from the potato in having a relatively large proportion of nitrogenous substances, as much as 22 or 23%, while the carbohydrates amount to about half the weight of the P. Cheese, again, is a case of a food containing very little carbohydrate and a high proportion of proteate. An average composition is 34% of water, 28% of proteate, 33% of fat, and 2% of carbohydrate. As opposed to these mixed foodstuffs, sugar is a pure carbohydrate, butter is practically nothing but fat, with an admixture of water. All carbohydrates are ultimately obtained from the vegetable kingdom and of the numerous substances which belong to this class, none is better known than sugar. It must, however, be pointed out at once that the meaning which the ordinary person attaches to sugar is not quite what the scientist understands by it. The chemist speaks of sugars, for there are several distinct substances known to him which go under this name. There are, for instance, cane sugar, milk sugar, malt sugar, and grape sugar, or glucose. To these the reader might be inclined to add beet sugar, but this would be a mistake. The substances just mentioned are indeed named from their different sources, but it is not on that account that they are regarded as distinct members of the sugar class. Investigation has shown that they are chemically different. Even although in some cases the proportions of carbon, hydrogen, and oxygen are equal, the arrangement of the atoms in the molecules is not the same. The sugar, however, which is obtained from the beet, is chemically identical with that which comes from the sugar cane. Beet sugar, in fact, is simply cane sugar from another source. What we refer to in ordinary conversation as sugar, the article which appears on the breakfast in the tea table, is cane sugar, although in reality a great deal of it has been manufactured from beetroot. The inhabitants of these islands ought to be specially interested in this article, for the annual consumption per head of the population of Great Britain is about eighty pounds, which is equivalent to eighteen pieces of ordinary lump sugar per diem. This is nearly three times as great as the corresponding figure for France or Germany. Up till a hundred years ago there was practically no sugar produced except from the sugar cane, whereas now more than half the world's production of sugar is derived from the beet. The name cane sugar, therefore, is not quite so accurate a description of this compound as it once was. Much energy has been devoted to the scientific cultivation of the beetroot and to the proper extraction of the sugar which it contains. The advance which has been made in this way is very well illustrated by some published figures showing that whereas in 1836 a ton of beetroot yielded 124 pounds of sugar the same quantity in 1871 was made to yield 204 pounds in 1900-300 pounds of sugar. In the old methods of extracting sugar from the canes these were crushed and the juice which was thus pressed out was clarified and then boiled down until the sugar crystallized. Another and modern plan which is similar to the method used in extracting sugar from beet roots is to immerse the canes in water and soak out the sugar. The juice obtained in this way is then concentrated to its crystallizing point. The crystals are not pure and are spoken of as raw sugar. The un-crystallizable juice which is separated from the crystals, un-crystallizable because of the mixture of substances which it contains, is used as food in the form of treacle or molasses. Although a good deal of raw cane sugar finds its way into the market as the Marrera, the bulk of it is first refined. The process of refining consists in dissolving the raw sugar in water, filtering the brown solution through cotton bags, and then decolorizing it by keeping it in contact for some hours with animal charcoal. Contrary to what one might expect from the name, animal charcoal contains only one-tenth of its weight of carbon. It is got from bones in the same way as coke is obtained from coal, that is, by heating strongly in a retort. The organic matter in bones is charred by this treatment and the resulting carbon is distributed in a finely divided condition over the phosphate and carbonate of lime which constitute the bulk of the mass. In this state of fine division the carbon has the remarkable property of absorbing any coloring matter from a solution with which it is left in contact for a time. Red wine, for instance, if shaken with animal charcoal and then filtered, runs through as a colorless liquid like water. A colored sugar solution is similarly affected and pure sugar is then obtained by concentrating the decolorized liquid to the crystallizing point, as already described. It is somewhat startling to reflect that a heap of uninviting looking bones may be destined to purify our best lump sugar, but this is frequently the case. The reader need not trouble himself much about milk sugar, which forms five percent by weight of ordinary milk, or about malt sugar which is formed from grain in the preliminary stages of brewing beer, but grape sugar or glucose is quite an important carbohydrate and is worth a little attention. The very name suggests one of its sources, and as a matter of fact, grapes contain thirteen percent of glucose, the percentage present in dried fruits is much higher, and in figs is over fifty. The B must not be forgotten as an agent in the collection of glucose, for honey contains seventy to eighty percent of this sugar. It comes originally, of course, from the flowers, and an estimate of the sugary matter in these has shown that the B's must visit several hundred thousand heads in order to collect one pound of honey. We pride ourselves, and justly, on the methods by which minute amounts of a precious metal can be extracted from large masses of rock and earthy material, but the remarkable achievement of the B in the accumulation of almost microscopic quantities of sugar is probably unequaled. Glucose is not nearly so sweet as cane sugar, yet in the olden days, before cane sugar had been introduced, honey was the material used in sweetening dishes for the table. Later on, glucose was obtained from grapes, but nowadays it is made by boiling starch with dilute sulfuric acid. It is then known as starch sugar. It must be admitted that the names of the various sugars are a little confusing. Already we have seen that beet sugar is the same as cane sugar. Now it appears that starch sugar is nothing else than grape sugar. The starch required for the manufacture of glucose, by this method, is generally derived from potatoes or maize. It is made into a cream with water, and then run into boiling dilute sulfuric acid. In these circumstances the starch undergoes a gradual change, which the chemist describes as hydrolysis, and the boiling is continued until starch can no longer be detected in the liquid. The test is made by taking a sample out of the boiler, cooling it, and adding a little iodine, which gives a blue color so long as unchanged starch is present. Possibly the reader may at some time or other have accidentally dropped a little tincture of iodine on a starched article, say a shirt cuff, and noticed that a deep blue stain was produced. This is a very characteristic peculiarity of starch, and always serves for its detection. The solution of glucose obtained after hydrolysis is complete must of course be freed from the acid, which would be a most undesirable constituent of any foodstuff. The cooled liquid is accordingly neutralized with chalk or whiting, and the insoluble sulfate of lime which is formed is filtered off. It is further necessary to decolorize the solution by means of animal charcoal, and to concentrate by evaporation until the solid can be obtained. The glucose produced in this way will be a white substance provided sufficient care has been taken to decolorize the solution thoroughly by animal charcoal, otherwise the substance will have a light brown tinge. If the conversion of the starch should have been incompletely carried out, then a liquid glucose syrup is finally obtained, which although not so pure as the solid glucose may be used and is extensively used both in confectionery and brewing. Other carbohydrates as well as starch can easily be converted into grape sugar. Cane sugar itself is changed into glucose and another similar sugar called fructose merely by heating a solution with an acid, sulfuric acid for example. The cane sugar is said to be inverted, and the resulting mixture of glucose and fructose is known as invert sugar. This product is obtained in the form of a thick syrup, and is extensively employed in brewing. This reminds one that it was the use of sulfuric acid in the manufacture of glucose and invert sugar which led to the arsenic in beer scare of 1900. In Manchester during that year a number of cases of arsenic poisoning occurred and were ultimately traced to the beer drunk by the patients. Arsenic was found also in the glucose and invert sugar from which the beer had been brewed, having got into these materials from the sulfuric acid employed in their manufacture. It must be remembered that the sulfur required for making sulfuric acid is generally in the form of iron pyrites, a natural product which is invariably contaminated with arsenic. Unless therefore submitted to special purification, commercial sulfuric acid is liable to contain arsenic, and it was the use of such an impure acid in the manufacture of glucose and invert sugar that was at the bottom of the arsenic in beer trouble. The conversion of other carbohydrates into glucose can be brought about by certain ferments without the aid of acids at all. When moist barley, for instance, is allowed to germinate, a ferment called diatase is produced. This subtle agent upsets the equilibrium of the starch molecules in the barley. Under its influence they are converted into sugar molecules, and the latter, unlike starch, can be fermented by yeast and so produce alcohol. Again the conversion of starch into sugar is a chemical change of which the reader himself is the scene. As already pointed out, much of our common food contains carbohydrates, and of these starch is the one which is present in the largest proportion. Now starch itself consists of fine granules which are insoluble in cold water. On this account any form of starchy food should first be boiled or baked in the presence of moisture. This treatment secures the bursting of the granules. They are dissolved, or at least softened, and are so rendered amenable to attack by the digestive juices. This attack begins in the mouth where a ferment lying in wait in the saliva begins the conversion of starch into sugar, a process which is completed by the juices in other digestive organs. This important ferment in the saliva is not developed until several months after birth. The disadvantage therefore of giving starchy food to infants will be apparent. If such food is given it is not assimilated, for all other carbohydrates must be converted into glucose if they are to be made available for the nourishment of the body. For the further utilization of the glucose the liver is responsible, and if this organ is not doing its duty the sugar goes through the body unchanged and unassimilated. The presence of glucose in the urine is in fact taken as evidence of diabetes. In cases of this disease the patient should abstain from the use not only of sugar itself, but also of all starchy foodstuffs, for these latter, as we have seen, are rapidly converted into glucose by the digestive juices. Another interesting carbohydrate which is worthy of mention is dextrin, or British gum. This compound is a sort of halfway house between starch and glucose, and it is formed when starch is heated either alone or with a little acid. Although dextrin has the same chemical composition as starch it gives a reddish brown color with iodine instead of the blue color which is so characteristic of starch. Dextrin is applied to some curious purposes, for example as an adhesive on envelopes and postage stamps, in giving a gloss to paper and cardboard, and in producing a head on beer and aerated liquids. The possibility of converting the various carbohydrates into glucose is further illustrated by the changes which vegetable fiber or cellulose may be made to undergo. This is a carbohydrate of the same chemical composition as starch, but differs from the latter in being indigestible except by herbivorous animals which have a special apparatus for dealing with it. Cotton wool and Swedish filter paper are nearly pure cellulose, from which it will be obvious that this carbohydrate is not a suitable article for human food. When eaten it simply passes through the body without being digested. Cellulose, in either of the forms just mentioned, is dissolved by strong sulfuric acid. If the solution is diluted with water and subjected to prolonged boiling, the cellulose, like starch, only less readily, is converted into glucose. Bearing in mind that the fermentation of this sugar yields alcohol, the reader will perceive that it is actually possible to prepare spiritous liquids from linen or cotton rags, for these consist very largely of cellulose. From rags to alcohol, however, is a transformation which is a chemical curiosity rather than a practically applied process. The name cellulose suggests the commercial article known as celluloid, which is indeed derived from cellulose. In Chapter 15 it was shown that when cotton wool, that is cellulose, is treated with nitric acid, the explosive gun-cotton is obtained. If a weaker acid is employed, and the time during which it acts is shortened, another compound is produced, intermediate between cotton and gun-cotton. This product, when mixed with camphor and properly worked up, is celluloid. Although not explosive like gun-cotton, it is highly inflammable, and numerous burning accidents have been caused by the ignition of combs made of this material. Attempts have been made to render celluloid uninflammable, but this can be done only by sacrificing some of its valuable properties. One of these is its plasticity. Separate pieces of celluloid, when heated to a temperature a little above the boiling point of water, can be welded together by pressure, just as two pieces of red-hot iron are welded under the blacksmith's hammer. Then again celluloid can be planed, carved, or turned on the lathe, and the appearance of the article so produced leads to its name of artificial ivory. It is employed not only in combs, but in the manufacture of such various things as piano keys, billiard balls, dolls, and photographic films. At the beginning of this chapter carbohydrates were spoken of as important constituents of food, but it will now be evident that this important class of chemical compounds figures largely in common life apart from food stuffs. They are to be detected in our stationary, in our clothes, on our postage stamps, and indirectly in celluloid, and the many useful articles which are made of this material. CHAPTER XXI. The romantic element about suet, candles, butter, soap, and linseed oil is, it must be confessed, not particularly prominent. And yet there is perhaps no class of natural products which ministers in a more wonderful and varied fashion to the needs and comforts of man than the fats and oils. Versatility in an individual, the ability to do half a dozen things of the most diverse description, is always interesting, and the study of the way in which the stream of natural products is diverted by the wit of man into all sorts of useful channels is similarly fascinating, if not romantic. Fats and oils are natural products, their name is legion, and there is an inexhaustible supply. The oils, however, with which we shall chiefly deal in this chapter, are those which can be described as liquid fats. There will indeed be a brief reference to the so-called mineral oils which are derived from the petroleum springs of Russia and America, already described in Chapter XII. But the volatile or essential oils, like oil of nutmeg or oil of lemons, will be left out of account, at least for the present. If we omit consideration of the mineral and the essential oils, we may say that the numerous fats and oils derived from both the animal and the vegetable kingdoms are remarkably similar in chemical composition, however diverse their origin. A fat or fatty oil is a substance analogous to a salt, which, as already shown, is a neutral compound produced by the combination of an acid and a base. The constituent of the fats and oils, which corresponds to the base of a salt, is glycerin, while the acid is very often steric, oleic, or palmitic acid. The compound formed by the union of glycerin, and one of these fatty acids, is termed a glyceride, and the commonly occurring fats and oils are to be looked on as mixtures of different glycerides. That fats and oils are obtained from an extraordinary variety of sources is shown by the fact that hogs kidneys, cotton seed, milk, hazelnuts, cod livers, and cows feet are among the raw materials requisitioned for the purpose. Fats and oils of a vegetable origin are obtained mostly from fruits, which in some cases contain a high proportion of fatty material. The fruits of the olive tree contain about half their weight of oil, used for instance in packing sardines, while in the seed of the flax plant there is 30 to 35% of oil, familiar to everyone as linseed oil. A vegetable oil is extracted from the seed in one of two ways. The seed is either crushed under pressure so that the oil is squeezed out, or it is heated with some volatile liquid, such as petroleum or carbon disulfide, which dissolves out the oil and can afterwards be boiled away. When the first method is employed, the expressed oil is collected in suitable vessels, and the compressed residue, still containing a small proportion of oil, is sold as oil cake for feeding cattle. This way of utilizing the residue is obviously an economical one, for the unextracted oil is ultimately recovered from the cow or bullock in the form of butter, tallow, or neat's foot oil. The process most in vogue for obtaining animal fats and oils is known as rendering. The fatty material is boiled with water or steamed, and the oil which floats on the surface is removed. In this way it is obtained free from adhering tissue. Attention was drawn in the previous chapter to the fact that fats are one of the principal constituents of human food. Butter, lard, suet, olive oil, and cocoa butter may be mentioned as fats which are used either directly as food or in the preparation of dishes for the table. In this country we import over twenty million pounds worth of butter alone per annum, in addition to the butter made and consumed at home. Butter, however, is not the only fat which is used directly as human food. Margarine, an artificial mixture of animal fats, with possibly a small amount of vegetable fat, is manufactured in large quantities nowadays, the annual consumption in this country being estimated at about five million pounds worth. Its manufactured dates back to the time of the Franco-German War when the inhabitants of Paris were hard up for butter. This fact would seem to indicate that margarine is to be used only by those who are reduced to their last resources, but really no reasonable objection can be taken to this material when made under satisfactory conditions and sold under its own name. A member of parliament, referring on one occasion to margarine, spoke of, quote, all the greasy rubbish of the world which is being dumped down in this country, unquote, but this description is now quite out of date. Other edible fats turned out in large quantities are the so-called vegetable butters which are valued by our vegetarian friends and appear in the market under all sorts of fancy names. In India, where on religious grounds the natives will have nothing to do with animal fat of any description, vegetable butter is prepared in large quantities from coconut oil and palm nut oil. The Greenlander, on the other hand, who has no such scruples, revels in blubber. The preparation of edible butters and oils is only one of the many industries which depend on the utilization of fats and oils. If it were not for their disguise, for the chemical processes to which they have been subjected, we should detect these materials in many an unsuspected place. They may be traced not only in the butter on our bread, but also in the candles which light our tables, on the artist's canvas, in the linoleum on our floors, and in the matchless cleansers which delight the housewife's heart. The chemical processes which have been referred to as disguising the obvious characteristics of fats and oils are not all carried out by the manufacturer. There is one class of oils, the so-called drying oils, the value of which is due actually to their own instability and to their sensitiveness to atmospheric influences. Common linseed oil obtained from the seeds of the flax plant is the typical member of this class. If a film of linseed oil is exposed to air, it absorbs oxygen with great evidity, becoming gradually more and more sticky and viscous during the absorption, until at last it dries to an elastic skin. The amount of oxygen thus absorbed by the oil may be as much as 20% of its weight. In this respect, linseed oil is absolutely different from, say, olive oil, which remains liquid, however long it is exposed to the air, and is therefore described as a non-drying oil. The complete drying of a thin layer of linseed oil occupies about three days, but the process may be considerably accelerated by a certain device, as was shown long ago by a Dutch artist. He found that if the ordinary or raw linseed oil were previously heated to a high temperature with lead oxide, the time required for drying was shortened to six or eight hours, an observation which has turned out to be a very valuable contribution from art to practical science. At the present day, linseed oil, which is to be used in the manufacture of paints, is subjected to a preliminary treatment of the kind suggested by the Dutchman. The only difference is being that the temperature now employed is not so high, only about 300 degrees Fahrenheit, and other dryers besides lead oxide may be used. The product is known as boiled oil, though strictly speaking it has never been boiled at all, but only heated. Fatty oils would, as a matter of fact, decompose if we attempted to boil them. The name boiled oil is one of those little inaccuracies of terminology which one comes across occasionally in the technical world, a terminological inexactitude, the politicians would call it. The case is parallel to black lead, which as the reader will have learned from Chapter 5, contains no lead at all. As already indicated boiled oil is extensively used in the preparation of paints and varnishes. The coloring material, white lead, lamp black, ultramarine, or red lead as the case may be, is first ground with a small quantity of linseed oil, and then mixed with more oil, generally of the boiled variety, and with oil of turpentine. When a layer of the paint is spread on a surface of metal or wood, it dries quickly, and a protective skin is left. The drying of wet paint the reader will now perceive is quite different from what takes place when a newly washed cloth is hung out on the clothesline. In the latter case, simple evaporation of water, a purely physical process takes place, while the drying of paint involves a chemical change, the combination of the oil with oxygen from the air. Like the painter, the glazier depends on the drying qualities of linseed oil when he fixes up a new paint of glass with putty. This dough-like material is obtained by grinding up whiting with linseed oil, and it is the latter ingredient which is responsible for the gradual hardening of the mixture on exposure to air. This curious drying power of linseed oil is made to contribute to the equipment of our houses, not only in paint, but also in linoleum. Linseed oil is the raw material of the linoleum manufacturer, and the first operation in the factory is the drying of the oil on a large scale. This is affected by hanging up sheets of textile material and allowing the oil to run slowly over them. Under these circumstances, it dries gradually to a tough gelatinous mass. This oxidized and solidified linseed oil is then mixed with rosin and ground cork, spread on a canvas backing, and sent into the market as linoleum. One purpose for which drying oils are obviously not suited is lubrication. If linseed oil were put into the bearings of a machine, it would get viscous and tough in the manner already described, and the running of the machinery would be hindered instead of helped. For lubricating purposes, a non-drying oil is required, such as tallow oil, lard oil, knitzfoot oil, olive oil, rape oil, or castor oil. The metallic variety of palm oil, which travelers frequently find necessary to stimulate official activity or to produce temporary blindness in the official eye, might be classed as a lubricant, but the naturally occurring variety, which by the way is a solid, not a liquid, finds only a limited application in this direction. The use of fatty oils for lubricating purposes has been greatly restricted in recent times by the introduction of mineral oils obtained from petroleum wells. It must be born in mind that the fatty oils are compounds of glycerin and an acid, and that under certain conditions, when exposed for instance to the action of high-pressure steam, they may be split up into these constituents. This means that the use of a lubricating fatty oil may lead to the formation of free acid on the bearings, a result which, in view of the corrosive action of acids on metals, is highly undesirable. No objection of this sort can be urged against the petroleum or mineral oils, for these are simply hydrocarbons, compounds of carbon and hydrogen, and as such are unaffected by air or steam. Hence, it comes that for lubricating purposes, fatty oils have been largely displaced by mineral oils. As a matter of fact, most of the lubricating oils used at the present time are mixtures of the two varieties. The discovery of petroleum has very notably restricted the use of fatty oils in another direction, namely in their application as illuminants. It is not so very long ago since paraffin oil was a novelty, and up to that time vegetable oils, such as olive and rape oils, were largely employed as sources of light. Nowadays, we may say with confidence, the private individual uses nothing except paraffin as a burning oil. It is the railways which furnish the most conspicuous example of adherence to the old custom, the lamps used on signals being still fed with rape oil. In lighthouses, too, there is a certain extent of adherence to the old kinds of burning oil, in as much as whale and seal oil are largely employed in the lamps. It is true these are animal oils, in contrast to olive and rape oils, but they belong to the same class of chemical compounds. Fats and oils are made available for illuminating purposes, not only directly in the way just described, but indirectly also, after being subjected to chemical treatment by the manufacturer, and being made to yield up the fatty acids which they contain in combination with glycerin. In connection with the subject of lubrication, it was said that under the influence of high-pressure steam, a fatty oil might be decomposed into fatty acid and glycerin. Now, although this may be undesirable behavior in the case of a lubricant, yet it is precisely the change which the manufacturer brings about on a large scale in order to produce candles. Our forefathers, it is true, use unchanged fats in the manufacture of candles. We have all heard of tallow dips and the snuffers which went along with them. Tallow is the rendered fat of cattle and sheep, and consists chiefly of two fatty acid glycerides, those of steric and oleic acids. Together with a small quantity of the glyceride of palmitic acid, the mixture is easily melted, and the dip was made by repeatedly dipping a cotton wick in molten tallow. The wick in modern candle, on the other hand, is made of yarn, plated in such a way that the end of the wick bends over and is burned at the side of the flame as the reader has doubtless observed himself. Such a wick cannot be employed in a tallow candle, for the curving over of the end of the wick would shift its lower portion out of the center of the candle, tallow being such a plastic material. The end of the wick in a tallow dip keeps straight, and soon gets into the top of the flame where it is charred, but cannot get enough oxygen for complete consumption. It interferes with the proper burning of the candle, and the flame is rendered dull and smoky. From time to time therefore, the tallow candle must be snuffed, that is, the end of the wick must be removed. When tallow is treated with high pressure steam, it is split up or hydrolyzed, to use the technical term, and the three acids mentioned above are liberated from the sway of the glycerin. At this stage they are crude and dark in color, and are therefore subjected to distillation in a current of superheated steam. The nearly colorless mixture of the purified acids obtained in this way is subjected to pressure, so that the liquid oleic acid is squeezed out, the remaining product known as steering, and consisting mainly of stearic acid, is cast into candles in suitable molds. Steering does not melt below 160 degrees Fahrenheit, so that candles made of this material will keep erect even in tropical countries. For use in temperate climates, candles are usually made of a mixture of steering and paraffin wax, the latter being obtained in large quantities, about 24,000 tons a year, by the destructive distillation of Scottish shale. Candles are, as a matter of fact, made from paraffin wax alone, but they are rather soft and given to collapsing in hot weather. The tallow candle has been nearly ousted from the market by these modern competitors, but even yet the annual output of the former in this country amounts to a good many hundred tons. In addition to tallow, steering, and paraffin wax, beeswax also is used in the manufacture of candles. From the chemist's point of view, beeswax is quite different from paraffin wax, but similar to tallow, like the latter it is analogous to a salt, and results from the union of fatty acids and an alcohol, only in this case it is another alcohol than glycerin. The hydrolysis of a fatter oil into glycerin plus fatty acid is affected as we have seen by the action of superheated steam. By a modification of this procedure, we can obtain glycerin plus soap instead, for a soap is nothing more than the sodium or potassium salt of steric or palmitic acid. For the production of soap therefore, the fat instead of being treated with superheated steam, is boiled with caustic soda or caustic potash. If soda is employed, a hard soap results, potash on the other hand yielding a soft soap. For the separation of the soap from the glycerin, a vantage is taken of the fact that although soap is soluble in water, it is not soluble in a solution of common salt. The boiling of the fat with caustic soda is therefore followed up by throwing a quantity of salt into the boiler. The soap separates, rises to the top, and is removed to iron molds. Although the chemistry of soap making was not understood until about a hundred years ago, the art has been practiced for many centuries. At the present time, soap making is one of the leading chemical industries, and this country is ahead of all others both in regard to scientific methods of production and amount turned out of the factories. We not only make most of our own soap, but send over one million pounds worth annually to other countries. The candle and soap industries have this in common, that they both use fats as their raw material, and turn out glycerin as a by-product. Until the last quarter of a century, however, comparatively little attention was paid to this latter material. The soap maker indeed simply ran the spent liquors containing the glycerin, lyes as they were called, into the nearest water course. Nowadays, because of its use in the manufacture of nitroglycerin for dynamite and blasting gelatin, glycerin has become a valuable product, and successful efforts have been made to recover it from the spent liquors of the soapworks. This utilization of what was formerly run to waste has, of course, cheapened the production of soap. Indirectly, therefore, the discovery and manufacture of nitroglycerin and the explosives into which this dangerous substance enters may be regarded as promoting cleanliness. It has been stated on good authority that the flourishing condition of the soap industry in this country has been chiefly due to the profits arising from the recovery of the glycerin. In any case, there is no doubt that the utilization of waste products is very often of the greatest importance to the industry concerned. More than that, the history of by-products is a subject of the most fascinating interest, even to the general reader, and a subsequent chapter will accordingly be devoted to this matter. END OF CHAPTER XXI Everyone has doubtless observed that in the growing infant the bump of destructiveness is early developed, and that it is only at a later stage that this impulse to take things in pieces is succeeded by the desire to put together, to construct. In the gradual development of the science of chemistry we can detect similar stages. In one of these the energies of chemical workers were mainly directed to breaking down all the various substances found in nature and discovering the simplest elements of which matter consists. At another and later stage attention has been chiefly directed to building up from simpler materials the various products of the earth. We might, in fact, speak of the one method of work as destructive and of the other as constructive. Such destructive work or analysis as the chemist calls it has, however, served a very useful purpose. It was necessary to demolish the fantastic structures of the alchemist and to get down to the bedrock of fact before a building could be reared worthy of the name of science. Once the foundation was well and truly laid the constructive work of building, synthesis as the chemist calls it, could be taken in hand. Why, the reader may ask, should we treble ourselves to build up substances which nature readily supplies? Why not accept her gifts gratefully and cease worrying about synthesis? Now in at least one case which has already been mentioned the reply to these questions is quite simple. The value of nitrate of soda as a nitrogenous manure has been emphasized and at present the beds of this material in Chile are largely requisitioned for the purpose. But this is a case where nature's stores are limited and the prospect that in 30 or 40 years the supply from this source will come to an end has stimulated the discovery of some method of utilizing the vast stock of nitrogen in the atmosphere. The way in which this is being affected has already been described and it is sufficient to point out that the artificial production of nitrate regarded as an attempt to imitate nature has a very practical object. However it may be now there is no doubt that in the earlier stages of synthetic chemistry the work was undertaken and carried out purely in a spirit of scientific investigation without any reference to utility and without the expectation of favors to come in the shape of hard cash returns. Enumerable chemists have spent their years in unremitting toil striving only to let the light into many an obscure corner. Their labors may have led in after years to applications of great commercial value but all that these early pioneers had was the love of their work, the honor and the glory. Nowadays the commercial side of chemistry is very much in evidence and the laboratory is in many cases a necessary part of the factory, its brains in fact. Investigation and research carried out with the definite object of making money is a little less romantic than heroic attempts to win nature's secrets for the sake of knowledge alone but the former is more immediately practical and we must recognize that it has been very productive in results. Synthetic chemistry may be said to date from a certain red-letter day in 1828 when Voler succeeded in producing carbamid urea artificially. This bold statement does not sound very stirring but Voler's achievement was big with meaning for the years to come. It must be admitted that if the general reader were to listen to the long tale of Voler's discoveries he would probably not select the artificial production of carbamid as the most useful or the most interesting. A boy would be interested in Voler as the first to describe the curious behavior of mercury thiocyanate which swells up into worm-like shape when heated, a scene familiar to all who have looked at pharaoh's serpent. But Voler's fame does not rest on the discovery of pharaoh's serpent or even on the preparation of aluminum which he was the first to accomplish but mainly on the production of carbamid from inorganic materials. Now carbamid is essentially an animal product. The cast-off nitrogen of the human body is thrown out in the form of carbamid and the average adult produces about one ounce of this substance every day. It is got rid of in the urine which contains one to two percent of carbamid in the dissolved condition. At the time of Voler's discovery the view was everywhere held that the complex substances occurring in plants and animals were produced only by the action of a special vital force. It was therefore vain to hope that these products of the organism, organic substances as they were called, could possibly be obtained from the dry bones of inorganic material. Voler's success in producing carbamid in the laboratory from purely inorganic substances gave a severe blow to these old ideas. In fact it upset them altogether. Vital force was evidently not necessary for the production of organic substances, a conclusion which has been abundantly confirmed since Voler's time and is being daily confirmed in every chemical laboratory. Suppose now we try to fill in the details of this epic making discovery and to see how by mere laboratory operations it is possible to build up or synthesize carbamid from its elements. The inorganic substance which is most nearly related to carbamid is a compound of carbon, hydrogen and oxygen and nitrogen called ammonium cyanate and Voler discovered that by merely evaporating to dryness a solution of this compound in water a large proportion of it was changed straight away into carbamid. If then we show that ammonium cyanate can be made from its constituent elements in the laboratory we are justified in saying that carbamid can be produced artificially. The first link in the chain between the separate elements carbon, hydrogen, oxygen and nitrogen at the one end and ammonium cyanate at the other is acetylene. We have already seen that this gas can be produced from inorganic materials. By heating lime and carbon in the electric furnace calcium carbide is produced and to get acetylene from calcium carbide only water is required. But a more direct synthesis of acetylene is possible by making an electric arc between carbon rods in an atmosphere of hydrogen under these conditions acetylene which is a compound of carbon and hydrogen is produced in small quantity. Now acetylene gas when mixed with nitrogen gas and exposed to the action of electric sparks combines with the latter element forming prusic acid or hydrocyanic acid as the chemist calls it and when prusic acid is neutralized with potash we obtain the salt potassium cyanide a very poisonous compound of potassium carbon and nitrogen. Potassium cyanide can be very easily melted in an iron dish and in the molten state readily absorbs oxygen from the air forming a salt cold potassium cyanate a compound of potassium carbon nitrogen and oxygen. If this substance is dissolved in water and sulfate of ammonia added we get a double exchange taking place whereby ammonium cyanate and potassium sulfate are formed. This gradual building up of carbamid may be represented graphically in the following figure carbon plus hydrogen gives acetylene acetylene plus nitrogen gives prusic acid prusic acid plus potash gives potassium cyanide potassium cyanide plus oxygen gives potassium cyanate potassium cyanate plus ammonium sulfate provides ammonium cyanate which leads to carbamid. It may be objected that besides the four elements carbon hydrogen oxygen and nitrogen three compounds have been introduced into this synthesis namely potash water and ammonium sulfate. If space and the reader's patience permitted it might however be shown that these compounds can also be built up out of their constituent elements so that the whole chain is complete from the simple carbon hydrogen oxygen and nitrogen to the organic compound carbamid. Voler's wonderful discovery was interesting not only because carbamid was the first organic compound to be prepared in the laboratory from inorganic materials but also because it consists of the same elements as our present in ammonium cyanate and more than that the carbon hydrogen oxygen and nitrogen are present in exactly the same proportions in the two compounds. The extraordinary fact that two chemical compounds which are quite distinct in external appearance and behavior may contain the same elements united in the same proportions was very puzzling to chemists at that time although nowadays it is taking quite as a matter of course. Later workers have shown that such differences are due to a very subtle distinction in the way in which the atoms are arranged in the molecules. The internal anatomy of the molecule is different in the two cases. Since that red letter day in 1828 synthetic chemistry has made gigantic strides and we have learned to produce artificially hundreds of naturally occurring products. In many cases such an imitation of nature has very little interest for anybody outside of a chemical laboratory but on the other hand the synthetic product does occasionally come into the market as a competitor of the natural substance. An interesting example of this is furnished by the history of alizarin. For centuries this valuable dye stuff was obtained from the matter root and large areas of France, Holland, Italy and Turkey were given over to the growth of the plant. Cloth dyed with alizarin has been found on Egyptian mummies so that its use goes back to a remote age. Yet within the short space of 40 years this ancient product of the vegetable world has been unceremoniously hustled out of the market by the artificial dye. The latter can now be produced more cheaply than the natural alizarin with the result that the cultivation of the matter plant has almost ceased. The magnitude of the trade revolution thus due to the synthetic production of a natural dye may be gauged from the fact that for 10 years previous to the discovery of the value of the annual import of matter into Great Britain averaged one million pounds while 10 years later the value had sunk to 24,000 pounds. All this meant unemployment and privation to the people engaged in the cultivation of the matter plant but indeed it is frequently the case that the advance of science although beneficial to society as a whole involves suffering to many individuals. In explaining the synthesis of carbamid we were at pains to follow the success of steps by which it is possible to build up the final compound from the component elements. It must not be supposed however that the manufacturer of alizarin starts with the elements of which that substance is composed. As a matter of fact the chief raw material of alizarin is anthracene a hydrocarbon which is extracted from coal tar. It has been shown that this hydrocarbon can be synthesized in the laboratory and as everything else used in the manufacture of alizarin can be similarly built up from inorganic materials it follows that we have here an instance of the artificial formation of a complex natural product. The manufacturer however who has to consider the price of raw material and the cost of labor starts with some other natural product in this case anthracene which is at once cheap and easily obtained. Natural alizarin has gone down before the artificial product and a similar fate seems to be in store for another well known dye stuff namely indigo. It is some time now since chemists managed to produce indigo synthetically in the laboratory but as is frequently found it is a quite different thing to turn out products profitably on the manufacturing scale. Dividends become a prime consideration and the question arises whether the artificial product can be manufactured cheaply enough to compete successfully with the natural article. In the case of indigo the interval of time between the laboratory synthesis and the successful manufacture on a large scale was considerable. Years elapsed before all difficulties were overcome but science prevailed in the end and the artificial production of indigo on commercial lines is an accomplished fact. The raw materials on which the manufacture of indigo depends are one the hydrocarbon naphthalene two ammonia both obtained from coal three acetic acid obtained from wood four oxygen from the air. Starting with these chemists have elaborated a process whereby artificial indigo is turned out sufficiently cheaply to compete with the natural dye stuff. Already the latter has been hard hit and the cultivation of the plant from which it is obtained is apparently doomed. The value of the indigo exported from india was 3,570,000 pounds in 1895 and only 556,500 pounds in 1904. While of the total quantity of indigo consumed in the various countries of the world at the present time between 80 and 90% is the artificial product. This latter it must be clearly understood is not a mere substitute. It is exactly the same chemical compound as is derived from the plant. The synthesis of indigo on a manufacturing scale is indeed one of the most remarkable achievements of modern chemistry. It has been spoken of as a monumental example of scientific skill, patience, and resourcefulness and as absolutely unparalleled in the recent history of chemical industry. The reader will perceive that the advance of chemical science while it is to the interest of the community as a whole may involve serious trouble and possibly extinction to special industries. There is no partiality in the business. At one time it is France's turn to suffer from artificial alizarin, then India feels the competition of synthetic indigo. Now it looks as if Japan and China were to find out in a similar way what the advance of science may mean in connection with Canfra. True Japanese Canfra is obtained from a tree which belongs to the Laurel family and which is native to China and Japan. The wood is cut into small pieces and subjected to the action of steam whereby the volatile Canfra is carried off and condensed in a cool vessel. The amount of this crude Canfra annually exported from China and Japan has in recent years run to about 3,000 tons. Most of the Canfra supplied from these sources is employed in the manufacture of celluloid but a certain quantity is used up in medicinal preparations and in explosives. An enormous amount of labor has been expended in the study of the chemical nature of Canfra and this has at last borne fruit in the synthetic production of the substance. The starting point is turpentine, a resinous liquid which exudes from various trees belonging to the Pine family. When turpentine is boiled a liquid known as oil of turpentine distills over and from this liquid Canfra is produced by laboratory processes into which we cannot enter here. Synthetic Canfra is identical with natural Canfra in all ordinary physical and chemical properties and provided that a plentiful supply of turpentine at a moderate price is available the next few years may witness a repetition of what has already occurred in the cases of illizarin and indigo. It is a very confusing circumstance that there is also on the market a product known as artificial Canfra which indeed has an odor resembling that of true Canfra but which is chemically quite a different substance. Synthetic Canfra on the other hand is chemically identical with the natural product. Another and quite different direction in which we have been trying with success to imitate nature is in the manufacture of rubies. In an earlier part of this volume it was stated that Monson had been able to produce real diamonds so small however as to be of no ornamental value. The specimens commonly known as artificial diamonds are spurious. The paste used in their manufacture is chemically quite different from the diamond which as the reader knows is simply crystallized carbon. Artificial rubies however are chemically identical with the natural gems and are indistinguishable from them. Rubies and sapphires are practically pure alumina in the crystallized condition. They consist almost entirely of this compound of aluminum and oxygen. Aluminum itself is a colorless substance and the colors of the natural stones are due to the presence of small quantities of the oxides of chromium and iron. If the crystallized alumina is free from these other materials we have the mineral known as corundum which in hardness is second only to the diamond and with which in an impure form we are familiar as emery so that they useful in the ornamental in the shape of emery and ruby are very closely related. The artificial production of rubies depends simply on the careful fusion of alumina at high temperature and the addition of a small quantity of dichromate of potash to produce the color. Great care must be taken in the cooling of the fused alumina. If allowed to solidify and cool very rapidly it is in an unstable condition like glass which has been similarly treated. It is therefore annealed by putting the artificial ruby while still at a high temperature in a bed of silver sand so that the cooling takes place very slowly. Sapphires may be made in a similar fashion except that the coloring material added is oxide of cobalt instead of potassium dichromate. The artificial production of sapphires however has not been so successful as that of rubies. A new and very striking way of making these gems has been tried lately. It has been found that when natural colorless crystals of corundum white sapphires as they are called are exposed to the action of radium bromide they undergo a gradual change of color. Some specimens assume a blue tint others a pink and others still a brownish orange so that stones of any desired tint may be obtained. In these and many other ways then man has been trying and is trying to imitate and compete with nature. When we look back to that day in 1828 when the artificial production of carbamid was first accomplished we are filled with wonder at the marvelous advance which has been made in the interval. Not only have we learned how to obtain artificially numbers of valuable natural products but we can turn out of our laboratories and factories many useful chemical compounds which so far as we know do not occur in nature at all. We must however beware of pride. We must confess that although we can produce organic compounds in the laboratory we cannot turn out an organism. That is a different thing altogether and there is no prospect that the breath of life will ever be evolved from any chemical mixture however cunningly devised. End of Chapter 22 Chapter 23 of the Romance of Modern Chemistry this LibriVox recording is in the public domain. The Romance of Modern Chemistry by James C. Philip Chapter 23 the adulteration of food the chemist's imitation of nature as shown in the previous chapter has led to results of marvelous interest and practical value but in some cases unfortunately the imitation practice at the present time has an unworthy object just as there are some individuals who devote their chemical knowledge to the manufacture of bombs and infernal machines so there are others who engage in the objectionable practice of adulterating food. There have always been naves ready to defraud the public and the adulteration of food is no new thing. We have evidence on record that in past centuries bread wine butter and drugs were all liable to adulteration. Things are bad enough now but if one were to judge from a certain booklet published in the beginning of the last century the old days were even worse. This striking pamphlet has for part of its title deadly adulteration and slow poisoning and death in the pot and the bottle in which the blood and poisoning and life destroying adulterations of wines spirits beers bread flour tea sugar spices cheese mongery pastry confectionery medicines etc are laid open to the public and the author expresses himself occasionally in the gloomiest terms regarding the state of matters in his day. Bread he says turns out to be a crutch to help us onward to the grave instead of being the staff of life. In porter there is no support in cordials no consolation in almost everything poison and in scarcely any medicine cure. The adulterations practice at that time however were comparatively crude and with present-day methods and instruments they would be easily detected. As a result of the advance of chemical knowledge and practice the adulterator has been forced to refine his nefarious methods so that at the present time many of the alien substances introduced into our food can be detected only by the skilled analyst. For ways that are dark and tricks that are vain the modern adulterator would indeed be hard to beat. We must of course allow that if we call every foreign addition to our food and adulteration there are cases where the offense is not very heinous. As examples of these less objectionable additions we may take the coloring and flavoring of butter. Butterfat itself in the natural state has generally nothing like the yellow color which we are accustomed to see in the commercial article and the explanation is that in the great majority of cases an artificial coloring matter quite harmless in itself has been introduced. This is done it is said because the public prefers to have a highly colored article. Again the difference in flavor of various samples of butter is not natural. It is induced by the presence of certain microorganisms which are cultivated for the purpose. These adulterations although undesirable are not harmful and may be regarded as mildly fraudulent in comparison with others which are commonly practiced. Many common foods contain foreign materials introduced with the direct object of defrauding the public and securing a larger profit to the seller. Even ordinary foodstuffs of the breakfast table are not always what they seem with the exception perhaps of sugar on the purity of which one can depend. The reader may be interested to hear a little about the ways in which these foods are adulterated and about the methods by which the fraud can be detected. In the case of milk the chief and one might almost say the natural adulterant is water. New milk contains as much as eighty-seven percent of water and the uninitiated might suppose that it would be very easy to add a little more without detection. Careful analysis however will always reveal any such manipulation although it must be borne in mind that there may be a certain difference in the richness of milk from various cows. One method which the chemist has at his disposal is the determination of the specific gravity that is he finds out how much heavier the milk is than an equal bulk of water. It is worthwhile remembering that the first recorded determination of the specific gravity of a substance was in connection with the question of fraud. Hiro, the king of Syracuse, had commissioned a goldsmith to make him a crown out of a certain quantity of gold. When the smith brought the finished crown, Hiro somehow suspected that there was an admixture of base metal and asked Archimedes to find out for him whether this was so. The philosopher took a lump of pure gold equal in weight to the crown and put each into a vessel full of water. He found that more water overflowed from the vessel into which the crown had been put, then from the other, and concluded rightly that the crown must contain some lighter and baser metal. So the determination of specific gravity as a means of detecting fraud is a time-honored practice. If a bulk of water were taken which weighed exactly 100 ounces, an equal bulk of pure new milk would weigh about 103 ounces, a little less or a little more according to its source. That is, the average specific gravity of milk may be taken as 1.03. If then a certain sample of milk had a specific gravity of only 1.02, we might be sure that it had been watered. On the other hand, the fact that the specific gravity of a sample is 1.03 does not prove the milk to be satisfactory. For curiously enough, it is possible, by a judicious combination of watering and skimming, to get a product which has the same specific gravity as the original milk. The reader of course knows that the fact contained in the milk, in other words, the cream, rises slowly to the surface, but he may not have drawn the conclusion that this fat must therefore be lighter than the milk. What is left after removing the cream, that is, the skimmed milk, is actually heavier bulk for bulk than the fresh milk. Its specific gravity is higher than 1.03. By adding water to this skimmed milk in the proper proportion, the specific gravity is brought down to the normal figure 1.03 and this milk is indistinguishable from fresh milk unless further tests are applied. It will probably be suggested that a mere glance at this milk would show that it had been skimmed and watered, but our adulterator is not so easily caught. He perpetrates fraud upon fraud, exhibiting an ingenuity which is worthy of a better cause. A judicious admixture of a yellow dye to skimmed and watered milk is found to produce a rich creamy appearance, and the public is delighted with its milk supply. So is the adulterator. He has sold his milk at the standard price, and he has still the cream to dispose of. Since then, the appearance of the milk and even the determination of its specific gravity may fail to give away any proof of adulteration, further examination is necessary. The analyst must proceed to find also what is the amount of fat present in the milk. This is very quickly ascertained by treating a measured quantity in a centrifugal machine. The fat or cream under these circumstances separates almost immediately, and its bulk may be determined. If the amount of fat is less than three percent, the milk has certainly been tampered with, since the normal product never contains a smaller percentage of fat than this. A thorough examination would include also the determination of the non-fatty solids, consisting chiefly of casein and milk sugar. But a description of this would take us rather far. Butter is another household article that is readily infrequently adulterated, although the recent Butter and Margarine Act should do something to protect the public. The usual frauds practice in the case of butter are one, the sale of renovated or processed butter as fresh butter, and two, the substitution of a certain amount of cheap beef fat or lard for the true butter fat. Renovated butter is obtained from rancid butter by a process in which the objectionable matter is removed. The product is rendered sweet for the time being, and is sold as choice butter. Artificial butter on the other hand, or margarine, as it is commonly called, is prepared from beef fat or lard, which is worked up with ordinary butter and coloring matter, so as to resemble the real article. Besides a certain difference in the taste of butter and margarine, there is one very simple method known as the spoon test, by which they may be distinguished. If a little genuine butter is melted in a large spoon over a small bunsen flame, and the heating is continued, the butter ultimately boils quietly and foams up to the edge of the spoon. Margarine treated in the same way, splutters about and crackles, but does not foam. The practice of selling margarine under the name of pure butter is probably dying out, but it is not so very long since a bold individual was prosecuted for actually advertising a process for the scientific blending of butter with beef fat or lard. Science, it would seem, covers a multitude of sins. A food stuff which is frequently adulterated is chocolate. This substance is obtained by grinding cocoa nibs, which are the crushed kernels of cocoa beans. The nibs consist to about 45% of the fat, the so-called cocoa butter, and in this respect are quite different from the shells of the cocoa bean, which contain only two or three percent of the fat. Seeing that the price of cocoa nibs is about ten times that of cocoa shells, the common practice of adulterating chocolate with powdered cocoa shells is distinctly profitable. This fraud is best detected by the aid of the microscope, an instrument which is part of the necessary equipment of an analytical chemist laboratory. To the practiced eye, the presence of the powdered shells is at once obvious. There is another adulterant of chocolate or cocoa which is easily detected with the aid of the microscope, and that is starch. This substance is very widely distributed in the plant world and occurs in all sorts of vegetables and cereals. The samples of starch obtained from these various sources, such as wheat, rice, potatoes, and maize, are chemically identical, but when they are examined under the microscope, the granules of which they consist are found to be surprisingly different in shape and size. The granules of wheat starch are circular, those of potato starch are oval, while those of rice starch are many sided. The granules from maize starch, as found, for example, in corn flour, are also many sided, but are uniformly much larger than rice starch granules. It is therefore possible for a skilled analyst to determine with the microscope whether any starch, and if so what kind of starch, has been used in adulterating a given food stuff. He can also discover at once whether a certain kind of starch is pure or is contaminated with another kind. Obviously there is a temptation for the adulterator to add a cheap starch to a more expensive one, say potato starch to arrowroot, keeping the price the same. The microscope, however, soon exposes such a fraud. Substances which in some cases are to be regarded as regular adulterants are those used as preservatives. It is now generally agreed that a dairyman who knows his business does not require to add preservatives such as boric acid and formaldehyde even in the hottest weather. Moreover, the passage of these substances into the digestive organs is not to edification. The amount of formaldehyde which must be added to milk in order to preserve it is exceedingly small. One part in ten thousand of milk will keep the latter sweet for five or six days, but it must be remembered that in the case of children who consume considerable quantities of milk, the total amount of preservative taken into the system becomes appreciable. Similar objection may be taken to the employment of boric or boracic acid. This is used as a preservative of milk less frequently than formaldehyde, and it is generally mixed with borax, its sodium salt. Boric acid, by the way, has an interesting natural origin. Practically all the acid we use for preservative and other purposes comes from Tuscany, where numbers of steam jets of volcanic origin, Sofione as they are called, are to be found issuing from the ground. This steam contains small quantities of boric acid, and when a tank to hold water is built round the blowhole, the boric acid is condensed. It gradually accumulates in the water of the tank, and is then obtained by evaporation, the steam jets themselves being used to promote the process. Successful results have been obtained also from artificial Sofione, started by boring into the lower strata. There are other chemicals which are often used as food preservatives, such as salt, sugar, and vinegar. These substances are themselves foods to some extent, and they are therefore much less objectionable than purely antiseptic preservatives like boric acid and formaldehyde. The use of common salt, sodium chloride, in preserving butter and meat, is well known to everyone, and it is not regarded as an adulterant. A curious effect is produced when the solution in which beef is salted contains some salt peter, nitrate of potash, as well as sodium chloride. The salt peter causes the meat to preserve its natural red color, which would be destroyed partially, at least, by the action of common salt alone. Eggs are a form of food which is fortunately out of the reach of the adulterator, at least he cannot imitate the egg as a whole, and his turn comes only when the question of an egg substitute arises. In this line he has displayed his usual ingenuity, and brought out powders which are said to contain all the ingredients of eggs, but which on examination are found to fall very far short of that standard. In one case on record it was stated with a great show of authority that the composition of a certain egg substitute was based on the scientific analysis of natural eggs, which, it should be noted, contain a fair proportion of nitrogenous matter. When tested the product in question was found to be entirely innocent of nitrogen, and consisted of nearly pure tapioca starch with a little common salt and coloring matter added. This is another example of the way in which the name of science is taken in vain. End of chapter 23. Chapter 24 of The Romance of Modern Chemistry. This LibriVox recording is in the public domain. The Romance of Modern Chemistry by James C. Phillip. Chapter 24 The Value of the Byproduct It is perhaps difficult for the outsider to realize that the manufacture of useful and valuable materials, which has been rendered possible only by the advance of chemical science, but which we now take so much as a matter of course, has meant at the same time the production of enormous quantities of rubbish. The raw material which nature supplies may contain only a small proportion of the substance we wish to get from it. The rest is so much refuse, and unless we can devise some way of using it, has to go on the dust heap. We extract the gold, and the dross is left. Now rubbish heaps there will be as long as the world lasts, but provided that they are not a public nuisance, and that they are kept out of our sight, we accept them as a necessary evil. It will be readily admitted, however, that a rubbish heap which as late as 1888 covered 450 acres of ground, and was then receiving a trifling daily addition of one thousand tons, is no ordinary affair. This heap of alkali waste, about which we shall have more to say later on, was at the same time a public nuisance. The neighborhood was, and still is, pervaded by a most objectionable odor. There are many other cases in which the waste products of a chemical industry, although less obnoxious than alkali waste, accumulate at an altogether unmanageable rate, and it is no wonder that manufacturers and their chemists have made heroic attempts to deal with this rubbish problem. Indeed, the story of the way in which the attacking forces have slowly advanced had great expenditure of energy, patience, and fortune reads like a romance. The reader, however, will readily understand that besides the mere wish to avoid the awkward accumulation of rubbish, the desire to make something out of it has helped in the solution of the problem. The manufacturer is only too pleased if the chemist can tell him how waste material can be converted into a useful by-product. Indeed, history shows that the discovery of methods for utilizing the waste products of a chemical industry has frequently saved it from going down in the face of fierce competition. Economy demands some utilization of the waste material, and this has been effected with much profit to the manufacturer, even in industries where there is no particular difficulty in getting rid of it. An instance of the production of much waste material is to be found in the brewing industry. The main object of brewing is, of course, to get beer. But during the process of manufacture, a very large quantity of carbon dioxide is produced. The alcohol in the beer is obtained by the fermentation of a sugar, in which process sugar is changed into alcohol plus carbon dioxide. The quantity by weight of the carbon dioxide formed during the fermentation is almost equal to that of the alcohol, and the process is generally carried on in open vessels so that the gas simply escapes into the air and is lost. Carbon dioxide, that is to say, is a waste product of the brewing industry. It is quite easy to carry out the fermentation in closed vessels, provided only with an outlet for the carbon dioxide, and by this method the gas could be collected and condensed to the liquid form in steel bottles. In this shape, carbon dioxide is a marketable commodity. Such a conversion of the chief waste product of the brewing industry into a useful byproduct has actually been carried out, and the carbon dioxide so obtained has found application in refrigeration and in the preparation of aerated waters. Nowadays, however, the attempt to recover the carbon dioxide as a byproduct is very seldom made, because, from the commercial point of view, it is not worthwhile. A waste product which is more tangible but less easy to deal with than carbon dioxide is blast furnace slag. From what was said in a previous chapter, the reader will understand that iron smelting consists essentially in heating together crude iron oxide, carbon in the form of coke, and a flux, such as lime, to remove the earthy material from the ore in a fluid form. At the end of the operation, two things are obtained, namely pig iron and slag, the latter being simply the flux plus the earthy material from the iron ore. It is run out of the blast furnace in a molten condition, and is a sort of cross between glass and cinders. This unpromising material is turned out in Great Britain at the rate of nearly 20 million tons annually, and the mere removal of this refuse from the foundry involves the smelters in very considerable expense. In some cases, it is taken out and shot into the maw of the all-devouring sea. In other cases, as in the Black Country, it is allowed to accumulate in huge, unsightly mounds, veritable rubbish heaps of modern civilization. It is perhaps too much to hope that such an enormous mass of waste material will ever be entirely devoted to useful ends instead of disfiguring the landscape and covering up the fertile soil. But recent work has undoubtedly led to encouraging results in the utilization of slag. Much of it is employed in road-making and in reclaiming wasteland, but in addition, there is now made a very large quantity of slag cement, for which purpose the finely powdered slag is mixed with lime. Another purpose to which considerable quantities of slag are devoted is the making of slag wool. This curious product is somewhat similar to glass wool, the name in each case indicating a resemblance to cotton wool. When a jet of steam is directed against molten slag, little globules of the liquid material are blown off, each with a long, thin tail or filament. By mechanical means, the filaments are separated from the globules, and slag will consist simply of masses of the filaments. It is a non-conducting, non-inflammable material, and as such, is usefully employed in covering steam pipes and boilers. In virtue also of its non-conducting properties, it is used to coat refrigerating plant. It is very curious that while there has been such difficulty in utilizing blast furnace slag, there is another kind of slag turned out from Steelworks, which has found a ready application. If the reader considers for a moment how this basic slag, as it is called, is obtained, he will understand why it is a more valuable by-product than blast furnace slag. Steel is obtained by blowing air into molten pig iron. The impurities in the latter are thereby oxidized, and the purified metal is then supplied with the requisite quantity of carbon to convert it into steel. It is particularly important to get all the phosphorus removed from the metal, and this is best secured by adding quick lime to the molten pig. Any phosphorus which is present in the latter is oxidized by the blast of air, and is then in a condition to combine with the lime. The slag therefore, which is obtained at the end of the operation, contains phosphate of lime, and it is just the presence of this phosphate that makes basic slag valuable as a fertilizer. The greater part, say one and a half million tons of the basic slag, which is turned out of the steelworks of Europe, is sold for this purpose. The only thing necessary in order that its fertilizing power should be available is that it be finely ground. This is quite a straightforward operation, so that we have here an excellent example of the way in which the waste material of an industry is converted very simply into a valuable by-product. More striking than any of the cases yet quoted is the tale of the soda industry in Great Britain, not once, but twice during its history. A waste product of the most disagreeable description has become a valuable source of income to the manufacturer. Refuse has been converted into riches, and one of the by-products has actually become the most important part of the output. Carbonated soda is found in nature to a limited extent, but it is the artificial production which alone is of any importance. This goes back to about the time of the French Revolution when a certain Frenchman, Leblanc by name, first showed how to turn common salt into carbonated soda. Anyone who seeks to produce soda on a large scale is bound to start with salt, for it is the compound of sodium of which there is the most plentiful supply in nature. The process which Leblanc devised laid the foundation of an enormous industry and has given us cheap soap and cheap glass, but he himself, poor man, did not have much joy out of his invention. The unsettled nature of his time prevented his getting any profits. He did not even receive the reward promised by his own government, and at length, in disappointment and despair, he put an end to his own life. Leblanc's process for the manufacture of soda has been worked in England for about ninety years, and in order to appreciate its strange and checkered history, we must understand what the process is. The first stage is the conversion of common salt, chloride of soda, into sulfate of soda, or salt cake as it is called, by heating with sulfuric acid. This operation results not only in the formation of salt cake, but also in the evolution of torrents of hydrochloric acid gas. While the industry was in its infancy, the hydrochloric acid had little or no value and was allowed to go up the chimneys and pollute the air. The results of this were remarkable. The vegetation in the neighborhood of the alkali works was devastated, the smell pervading the atmosphere was noxious, and articles made of iron, such as locks, gutters, and tools, were rapidly corroded. No wonder that the alkali works were unpopular institutions. The manufacturers thought that by building very high chimneys, up to five hundred feet, the acid gas would get dissipated in the upper layers of the atmosphere. But this plan did not work out in practice, for the fumes descended like a pall on still wider areas, and the vegetation vanished. A striking commentary on the anxiety there was about eighteen forty, to get rid of this public nuisance, is furnished by the patent, which was taken out for a sort of floating salt-cake furnace, weather permitting the furnace was to be towed out to sea, and they are allowed to do its worst, so far as pollution of the atmosphere was concerned. Gradually, as time went on, another method of dealing with the waste hydrochloric acid came into vogue. This gas is very easily soluble in water, so that by making it pass through a chimney or tower packed with coke, over which water was constantly running, it was possible to absorb the greater part of the acid fumes. This was undoubtedly the right direction in which to go to work, but the absorption of the acid was never complete, and as the number of alkali works increased very rapidly, the public nuisance caused by the uncondensed acid vapors was as great as ever. It is estimated that even as late as 1860, the English alkali works were pouring out about a thousand tons of this corrosive hydrochloric acid gas every week. Besides, those manufacturers who went in for absorbing it were left with enormous quantities of the acid liquor on their hands. There was not much demand for this, it had little value, and the bulk of it was accordingly tipped into the nearest stream. Here the acid did fresh damage, for it killed all the fish. The people immediately concerned with the stream objected to its pollution, and complaints were very numerous. Altogether rather an awkward situation for the alkali manufacturers. Yet within the space of a few years, the whole aspect of affairs was altered. The hydrochloric acid, which had been such an unmitigated nuisance to everybody, since the start of the alkali industry, was discovered to be a valuable product. The alkali manufacturer became very careful to keep and use every particle of the substance, which a few years before, he would have given anything to be rid of. In fact, the utilization of the hydrochloric acid rapidly became the most profitable part of the manufacture of soda by LeBlanc's method. What was responsible for this sudden transformation, for this striking conversion of waste into wealth? One of the chief factors was undoubtedly the removal of the duty on paper in 1861, as the reader will agree, when the connection between these apparently unconnected events is explained. The removal of the restricting duty gave an immense stimulus to the demand for paper materials. Cotton and linen rags, which had previously served for the manufacture of paper, were no longer adequate to supply the demand. Other raw materials, straw, wood, and asparto grass were therefore requisitioned, but these substances had to undergo very drastic treatment before they appeared in the form of paper. Among other things, they required much bleaching, and the source of bleaching materials is hydrochloric acid. Chlorine, prepared from hydrochloric acid, is used for the purpose, either directly or after conversion into bleaching powder. The connection between the paper duty and the fortunes of the soda industry is therefore pretty obvious. The discovery of this valuable outlet for their hydrochloric acid and the passing of the alkali act in 1863 stimulated the manufacturers to devise improved methods of absorbing the acid. And so efficient is the absorption now that the escaping gases contain less than 0.2 grain of hydrochloric acid per cubic foot. Anyone who allows a larger proportion of the acid to escape is liable to a fine. Having seen the good fortune which at length attended the efforts of the alkali trade to get rid of waste product, we might suppose that there would be contentment all round, among the public as well as among the manufacturers. But this was not so, and the cause of trouble was the second stage of the Leblanc soda process. We have been so occupied in following up the history of the waste hydrochloric acid that we have yet to learn the fate of the salt cake which is produced at the same time. In the second stage of the Leblanc process the salt cake is mixed with limestone and coal dust and heated in a furnace. The chemical changes which take place in this furnace are somewhat complicated but the net result is a product known as black ash consisting chiefly of carbonate of soda and sulfide of lime. With the help of water the soda is extracted from the black ash, the portion which is insoluble being termed alkali waste. This objectionable refuse contains both the calcium from the limestone and the sulfur originally used in the manufacture of the sulfuric acid for the first stage. Of these the sulfur is especially valuable but for many long years no satisfactory method could be devised for recovering it from the waste which was simply thrown away. The accumulation of this waste material in the neighborhood of alkali works led to much unpleasantness even when it was stamped down and covered over with a layer of cinders moisture and air gradually got at the waste with the result that sulfur-redded hydrogen gas was given off into the atmosphere. Apart from the abominable odor such accumulations are themselves an eyesore and their magnitude is such that one can appreciate the importance of the soda industry from a mere glance at these rubbish heaps those in the neighborhood of the witness alone to which reference was made in the beginning of the chapter are estimated to contain 8 million tons of material. To the trouble which this waste brought upon the manufacturers of soda by Leblanc's method there was added the menace of serious competition. The ammonia soda process as it is called has during the last 30 years become a formidable rival of the Leblanc process and at the present day considerably more than half the world's production of soda is made by the newer method. Curiously enough while the Leblanc process was a French patent which has been worked mostly in England the ammonia soda process was an English patent which commended itself first and foremost to the Germans. This later method of manufacturing soda has many advantages and although we cannot go into details we may mention that Brian pumped directly from the salt beds is converted into soda in such a way that the product is a purer one than that yielded by the Leblanc method and that there are no disagreeable waste products. The reader might suppose that the ammonia soda process with all these advantages would speedily displace the older Leblanc process but the latter has offered a stubborn resistance a fact attributable to the once despised and obnoxious hydrochloric acid. The value of this byproduct has kept the Leblanc process going. At the same time everybody concerned realized that with this serious competition to face all must be done to affect economies and if possible recover that lost sulfur from the alkali waste. As one of the leading chemical manufacturers in this country said in 1881 the recovery of sulfur from alkali waste as a means of cheapening the cost of production by Leblanc's process has become of vital importance. At length after a series of abortive attempts success was attained. By a process patented in England in 1888 90% of the sulfur and alkali waste is recovered and can be sold as pure sulfur. Even in 1893 only five years after the patent was taken out 35,000 tons of sulfur were recovered by this method in England alone. From the public point of view also this utilization of alkali waste is welcome. For sulfur was the constituent of the waste which was responsible for its objectionable properties. Once the sulfur is removed as is done nowadays the residue is innocuous and unadjectionable so that the nose of the community is no longer offended. Not always have private profit and public interest been served together as in this utilization of alkali waste. With the economy thus affected the Leblanc process has entered on a new lease of life. At the same time it is interesting to note that some manufacturers who use the Leblanc process turn out no carbonate of soda at all but caustic soda, bleaching powder and pure sulfur. It is in respect of these secondary products that the Leblanc process has an advantage over its rival. The story of the soda industry is interesting because of its varying fortune and because of the illustration it furnishes of the value of the byproduct. Even yet it is not quite certain that the industry is at the end of its vicitudes. For the manufacture of alkali and bleach by electrolytic methods is being rapidly developed and bids fair to be a formidable competitor. Time only can show whether these new methods will be able to overthrow the older processes of soda manufacture. End of Chapter 24 Chapter 25 of the Romance of Modern Chemistry This LibriVox recording is in the public domain. Valuable substances from unlikely sources The last chapter will have shown the reader how waste products sometimes merely embarrassing in their character, sometimes definitely obnoxious, can be brought to play their part in our industrial economy. We are encouraged to believe that everything has its place, could we but find it out, and that the waste material of our industries is frequently wealth in disguise. Perhaps in no case has the disguise been more complete than in the byproducts of gas manufacture. Some reference has already been made to these in Chapter 13, but the lessons of the alkali trade may be suitably enforced by a study of the marvelous story of coal tar and other equally unsavory products of the gasworks. Here also, science has shown how useful and beautiful substances can be obtained from the most unpromising material, and how so-called waste products can be made to contribute largely to revenue. The reader may remember that in the dry distillation of coal, four products are primarily obtained, namely coke, ammoniacal liquor, tar, and coal gas. Little more need be said about the coke and the gas, except to point out again that even the sulfur-redded hydrogen in the latter, which must be removed on account of its harmful character, is made to pay part of the cost of production. The amount of sulfur in coal is very small, only one to two percent, equivalent to an average of about 35 pounds per ton. Only about one-third of this amount reaches the gas purifiers as sulfur-redded hydrogen, and yet so large is the quantity of coal which is treated in the gasworks of Great Britain, that in the aggregate the recovered sulfur amounts to thousands of tons per annum. In some gasworks this recovered sulfur is used in the preparation of sulfuric acid, which in its turn is employed in fixing ammonia and forming ammonium sulfate. Besides the sulfur-redded hydrogen, there is another impurity in crude coal gas which has to be removed, and which at the same time is made to contribute to the cost of production. This is the poisonous compound of hydrogen, carbon, and nitrogen, known as hydrocyanic acid. By suitable chemical methods it is extracted from the crude gas and converted into potassium ferrocyanide, a substance which is perhaps better known as yellow pressiate of potash. From this product it is easy to prepare either pressure in blue for the manufacture of printing ink or potassium cyanide. This latter compound is extensively employed in gold extraction and in electroplating. Thus it is that the objectionable impurity present in the crude coal gas to the extent of less than one part in 1,000 is converted into useful products. Another valuable byproduct of gas manufacture is sulfate of ammonia obtained from the ammonia-coal liquor. The amount of nitrogen in coal is 1 to 2 percent, but only a part of this is obtained in the form of ammonia. Roughly speaking, we may say that for every ton of coal put into the gas retorts 25 to 30 pounds of ammonium sulfate are recovered from the liquor. In Great Britain, the annual output of ammonia from the gas works alone in the form of ammonium sulfate is enormous, about 160,000 tons. It is valued as a nitrogenous manure and large quantities of it are exported to Germany and other countries for this purpose. The remaining primary byproduct of coal gas manufacture is tar, the unlovely qualities of which need no exposition. Yet out of this dirty, sticky substance the chemist has been able to evolve all manner of useful and wonderful things as we shall see presently. To begin with, we may note that the tar helps to pay the cost of producing coal gas as is shown by the following table. This gives approximately the amounts of the various charges incurred in manufacturing 1,000 cubic feet of coal gas as well as the prices which the byproducts or residuals will fetch. Cost of 1,000 cubic feet of gas 200 weights coal at 11 shillings 6 pence per ton 1 shilling 1 3 quarter pence Purification 1 half pence Salaries 1 half pence Wages 2 and a quarter pence Maintenance 3 and a half pence Total 1 shilling 8 and a half pence Returns from residuals of 200 weights of coal Coke 6 pence Tar 1 gallon 1 and 1 quarter pence Ammonia bryproducts 2 and 1 quarter pence Total 9 and a half pence The net cost therefore of making 1,000 cubic feet of gas in the holder is about 11 pence The share borne by the residuals in defraying the cost of making coal gas has an important bearing on the question of gas versus electricity for lighting purposes. No doubt electricity has replaced gas to a considerable extent but apart from the fact that gas is now largely employed for heating the constant discovery of new uses for the byproducts of gas manufacture tends to cheapen the cost of production. For long after the introduction of coal gas the tar was a nuisance a disagreeable byproduct the removal of which involved the manufacturer in considerable expense the demand for it was exceedingly small and far short of the quantity which was turned out of the gasworks. Two men who carried on the distillation of tar in these early days have left it on record that the gas company gave them the tar on condition that they removed it at their own expense. The volatile spirit or naptha which these two workers got by distilling tar was employed by Mr. McIntosh of Glasgow in dissolving India rubber for the manufacture of the waterproof material which bears his name. In 1838 a patent was taking out for impregnating or pickling wood with heavy oil from coal tar and this proved an important outlet for the gas manufacturer's refuse. Wood that has to be exposed to the action of water or to a moist soil will last much longer if it is steeped in this creosote oil and for the treatment of railway sleepers telegraph poles and wooden beams for harbor works etc. it is extensively used even at the present day. For the naptha however which was distilled out of the tar before it was used for pickling timber there was a very limited outlet. Some was used for dissolving India rubber or making varnish and some was employed for illuminating purposes. A patent flare lamp for the combustion of this naptha was invented 60 years ago and is still part of the regular equipment of a coasters barrow. The thorough utilization of coal tar was not possible until chemists had made a complete study of its constituents. This was carried out to a large extent by the middle of last century. And one result of these investigations was to demonstrate the presence in coal tar of the following important compounds benzene, toluene, phenol or carbolic acid naphthalene and anthracene. All of these except phenol are compounds of carbon and hydrogen that is hydrocarbons. And their importance arises from the fact that they are the starting points for the manufacture of the aniline dyes and other synthetic products of that kind. The actual proportion of these five compounds in coal tar is not great as a rule perhaps less than 12% but they are the constituents which chiefly concern us here. They are extracted from coal tar by the process of distillation. Some are much more volatile than others and when the tar is boiled these distill over first are condensed and so are separated from the less volatile constituents. The temperature of the tar in the boiler is continuously raised and the process of separating a more volatile from a less volatile part is repeated. In this way the tar distiller obtains a number of portions or fractions and has finally left in his boiler a quantity of pitch amounting to about 60% of the original tar. The various fractions in which the distillate is collected are known as first runnings, light oil, carbolic oil, creosalt oil, and anthracene oil. When each of these is further subjected to fractional distillation the important compounds already mentioned are obtained in a state of comparative purity. All this clever sifting out of the constituents of coal tar was very interesting from the purely scientific point of view and though that alone would never have made coal tar the highly important commercial product that it is today still we must admit that the present realized value of coal tar goes back ultimately to those purely scientific researches carried on about the middle of last century. It is well to realize how much of our modern comfort and luxury is traceable to such researches for there is sometimes a disposition on the part of the commercial world to scoff at anything which cannot be shown to have an immediate use. This is a narrow view of the acquisition of knowledge. The history of the last half century teaches us, most emphatically, that the advance of a chemical industry is secured not by the employment of practical men only but by the cooperation of these with the skilled chemist. The apparently unpractical researchers of the latter are, with the aid of the engineer, converted into practical manufacturing processes. We in Great Britain have been slow to appreciate the value of the trained chemist and the research laboratory. The result is that we have suffered in certain industries where these factors are essential to success. Yet it was an Englishman who made the discovery on which the whole coal tar industry is founded. In 1856, the late Sir William Perkin, while still a lot of 18, discovered that when aniline was oxidized by dichromate of potash, a beautiful purple coloring matter which we now speak of as mauve was produced. A demand soon arose for this. The first artificial dye and Perkin, with the assistance of his father and brother, started a small factory for its production at Greenford, near London. The importance of Perkin's discovery in relation to the utilization of tar lies in this, that although aniline, the raw material for the manufacture of mauve and other dyes, occurs only in traces in coal tar. It is very easily produced from benzene, which, as we have seen, is one of the regular constituents. For this purpose, benzene is first treated with nitric acid, which converts it into nitrobenzene, a substance which in smell closely resembles oil of bitter almonds and which is used in senting soaps. Nitrobenzene, when treated with iron filings and hydrochloric acid, is converted into aniline. This liquid is a basic substance, which contains the elements carbon, hydrogen, and nitrogen, and unites readily with acids to form salts. Perkin's discovery, therefore, that aniline was the parent substance of artificial coloring matters, meant that there was a new outlet for the benzene from coal tar. Mauve was only the first of a long series of artificial dyes, which chemists have succeeded in building up out of the constituents of coal tar. Some of these, such as Alizarin and Indigo, have competed successfully with the naturally occurring dye, while others, so far as we know, do not occur in nature at all, but are of purely laboratory origin, such as Magenta and Bismarck Brown. The phenomenal growth of the artificial color industry can best be realized by contrasting the modest works at Greenford, where Perkin began the manufacture of Mauve with the extensive dye works of Germany at the present time. The manufacture of artificial coloring matters has there attained the rank of a distinctively national industry, and the annual value of the dyes exported to other countries is about eight million pounds. It is a somewhat bitter reflection that the foundation of this huge industry was laid in England, and that it flourished here for about twenty years after its start, only to dwindle subsequently to unworthy proportions. The truth is that the German manufacturers recognize the value of the scientifically trained man in this industry above all others. They spent large sums on laboratory investigations and the confidence that these would ultimately bear fruit, and their faith has had its reward, would that our English manufacturers had had a little more of this virtue. The importance of the coal tar products in the modern world was lately emphasized by the celebration of the coal tar jubilee in 1906. After the lapse of fifty years, chemists, manufacturers, and dyers from all parts of the world met in London to honor Sir William Perkin, the founder of the industry. The chief meeting was held in the Royal Institution, where in 1825 another English chemist, Faraday, discovered benzene, the hydrocarbon which, one might say, has been at the bottom of the whole business. On the table at which distinguished men of science and industry offered their congratulations to Sir William Perkin, stood a small bottle of benzene, the identical specimen which Faraday had prepared eighty years before. The whole story of how the aniline and other dyes have been produced from such an uninviting mess as coal tar is really marvelous. It is truly, as someone has said, a romance of dirt. We must remember too that coal tar has been made to yield many other valuable products besides coloring matters. Even punch at one time felt moved to wonder at the host of things that have their origin in coal tar and delivered himself of the following lines. There's hardly a thing that a man can name of use or beauty in life's small game, but you can extract an olympic or jar from the physical bases of black coal tar, oil and ointment and wax and wine and the lovely colors called aniline. You can make anything from a saff to a star if you only know how from black coal tar. Anything from saff to a star is rather a big order, but the variety of purposes to which the derivatives of coal tar are applied is certainly very remarkable. In photographic developers in the color of microscopic sections in patent fuel in the color of our butter in artificial perfumes in the surgeons antiseptics in the latest shade of tie and in the explosive lidite we may detect the trail of the tar. Some readers may be interested to know that among the drugs to which the study of benzene and its derivatives have led are the well-known anti-pyrene and finazetine as well as a host of others which would not be so familiar. Whoever wants a local anesthetic, a hypnotic, or an antiseptic can have his requirements met by something which has been derived from coal tar. As a last example of the unexpected things that have cropped up during the study of coal tar products we may take saccharin. This substance is prepared from the hydrocarbon toluene and therefore indirectly from coal tar. Its most remarkable property is its sweetening power which is said to be 300 times as great as that of sugar. This being so it might be looked on as a formidable competitor of sugar but doubts have arisen as to its suitability as a food and its sale is now restricted by law in every European country. It can be purchased at the drug shop but not at the grocers. It is valuable to people who suffer from diabetes and who have therefore to avoid the use of sugar. Enough has been said in this chapter to convince the reader that very valuable substances can be obtained from the most unlikely sources. If he is an optimist these facts will help to confirm him in his view of life. If he is a pessimist prone to see the unlovely side of things he does well to realize that there is beauty even in coal tar.