Creative Chemistry Part 8

Nowadays such things as celluloid and pyralin can be sold under their own name, but in the early days the artificial plastics, like every new thing, had to resort to _camouflage_, a very humiliating expedient since in some cases they were better than the material they were forced to imitate. Tortoise sh.e.l.l, for instance, cracks, splits and twists, but a "tortoise sh.e.l.l" comb of celluloid looks as well and lasts better. Horn articles are limited to size of the ceratinous appendages that can be borne on the animal's head, but an imitation of horn can be made of any thickness by wrapping celluloid sheets about a cone. Ivory, which also has a laminated structure, may be imitated by rolling together alternate white opaque and colorless translucent sheets. Some of the sheets are wrinkled in order to produce the knots and irregularities of the grain of natural ivory. Man's chief difficulty in all such work is to imitate the imperfections of nature. His whites are too white, his surfaces are too smooth, his shapes are too regular, his products are too pure.

The precious red coral of the Mediterranean can be perfectly imitated by taking a cast of a coral branch and filling in the mold with celluloid of the same color and hardness. The clear l.u.s.ter of amber, the dead black of ebony, the cloudiness of onyx, the opalescence of alabaster, the glow of carnelian--once confined to the selfish enjoyment of the rich--are now within the reach of every one, thanks to this chameleon material. Mosaics may be multiplied indefinitely by laying together sheets and sticks of celluloid, suitably cut and colored to make up the picture, fusing the ma.s.s, and then shaving off thin layers from the end.

That _chef d'oeuvre_ of the Venetian gla.s.s makers, the Battle of Isus, from the House of the Faun in Pompeii, can be reproduced as fast as the machine can shave them off the block. And the tesserae do not fall out like those you bought on the Rialto.

The process thus does for mosaics, ivory and coral what printing does for pictures. It is a mechanical multiplier and only by such means can we ever attain to a state of democratic luxury. The product, in cases where the imitation is accurate, is equally valuable except to those who delight in thinking that coral insects, Italian craftsmen and elephants have been laboring for years to put a trinket into their hands. The Lord may be trusted to deal with such selfish souls according to their deserts.

But it is very low praise for a synthetic product that it can pa.s.s itself off, more or less acceptably, as a natural product. If that is all we could do without it. It must be an improvement in some respects on anything to be found in nature or it does not represent a real advance. So celluloid and its congeners are not confined to the shapes of sh.e.l.l and coral and crystal, or to the grain of ivory and wood and horn, the colors of amber and amethyst and lapis lazuli, but can be given forms and textures and tints that were never known before 1869.

Let me see now, have I mentioned all the uses of celluloid? Oh, no, there are handles for canes, umbrellas, mirrors and brushes, knives, whistles, toys, blown animals, card cases, chains, charms, brooches, badges, bracelets, rings, book bindings, hairpins, campaign b.u.t.tons, cuff and collar b.u.t.tons, cuffs, collars and d.i.c.kies, tags, cups, k.n.o.bs, paper cutters, picture frames, chessmen, pool b.a.l.l.s, ping pong b.a.l.l.s, piano keys, dental plates, masks for disfigured faces, penholders, eyegla.s.s frames, goggles, playing cards--and you can carry on the list as far as you like.

Celluloid has its disadvantages. You may mold, you may color the stuff as you will, the scent of the camphor will cling around it still. This is not usually objectionable except where the celluloid is trying to pa.s.s itself off for something else, in which case it deserves no sympathy. It is attacked and dissolved by hot acids and alkalies. It softens up when heated, which is handy in shaping it though not so desirable afterward. But the worst of its failings is its combustibility. It is not explosive, but it takes fire from a flame and burns furiously with clouds of black smoke.

But celluloid is only one of many plastic substances that have been introduced to the present generation. A new and important group of them is now being opened up, the so-called "condensation products." If you will take down any old volume of chemical research you will find occasionally words to this effect: "The reaction resulted in nothing but an insoluble resin which was not further investigated." Such a pa.s.sage would be marked with a tear if chemists were given to crying over their failures. For it is the epitaph of a buried hope. It likely meant the loss of months of labor. The reason the chemist did not do anything further with the gummy stuff that stuck up his test tube was because he did not know what to do with it. It could not be dissolved, it could not be crystallized, it could not be distilled, therefore it could not be purified, a.n.a.lyzed and identified.

What had happened was in most cases this. The molecule of the compound that the chemist was trying to make had combined with others of its kind to form a molecule too big to be managed by such means. Financiers call the process a "merger." Chemists call it "polymerization." The resin was a molecular trust, indissoluble, uncontrollable and contaminating everything it touched.

But chemists--like governments--have learned wisdom in recent years.

They have not yet discovered in all cases how to undo the process of polymerization, or, if you prefer the financial phrase, how to unscramble the eggs. But they have found that these molecular mergers are very useful things in their way. For instance there is a liquid known as isoprene (C_{5}H_{8}). This on heating or standing turns into a gum, that is nothing less than rubber, which is some multiple of C_{5}H_{8}.

For another instance there is formaldehyde, an acrid smelling gas, used as a disinfectant. This has the simplest possible formula for a carbohydrate, CH_{2}O. But in the leaf of a plant this molecule multiplies itself by six and turns into a sweet solid glucose (C_{6}H_{12}O_{6}), or with the loss of water into starch (C_{6}H_{10}O_{5}) or cellulose (C_{6}H_{10}O_{5}).

But formaldehyde is so insatiate that it not only combines with itself but seizes upon other substances, particularly those having an acquisitive nature like its own. Such a substance is carbolic acid (phenol) which, as we all know, is used as a disinfectant like formaldehyde because it, too, has the power of attacking decomposable organic matter. Now Prof. Adolf von Baeyer discovered in 1872 that when phenol and formaldehyde were brought into contact they seized upon one another and formed a combine of unusual tenacity, that is, a resin. But as I have said, chemists in those days were shy of resins. Kleeberg in 1891 tried to make something out of it and W.H. Story in 1895 went so far as to name the product "resinite," but nothing came of it until 1909 when L.H. Baekeland undertook a serious and systematic study of this reaction in New York. Baekeland was a Belgian chemist, born at Ghent in 1863 and professor at Bruges. While a student at Ghent he took up photography as a hobby and began to work on the problem of doing away with the dark-room by producing a printing paper that could be developed under ordinary light. When he came over to America in 1889 he brought his idea with him and four years later turned out "Velox," with which doubtless the reader is familiar. Velox was never patented because, as Dr. Baekeland explained in his speech of acceptance of the Perkin medal from the chemists of America, lawsuits are too expensive. Manufacturers seem to be coming generally to the opinion that a synthetic name copyrighted as a trademark affords better protection than a patent.

Later Dr. Baekeland turned his attention to the phenol condensation products, working gradually up from test tubes to ton vats according to his motto: "Make your mistakes on a small scale and your profits on a large scale." He found that when equal weights of phenol and formaldehyde were mixed and warmed in the presence of an alkaline catalytic agent the solution separated into two layers, the upper aqueous and the lower a resinous precipitate. This resin was soft, viscous and soluble in alcohol or acetone. But if it was heated under pressure it changed into another and a new kind of resin that was hard, inelastic, unplastic, infusible and insoluble. The chemical name of this product is "polymerized oxybenzyl methylene glycol anhydride," but n.o.body calls it that, not even chemists. It is called "Bakelite" after its inventor.

The two stages in its preparation are convenient in many ways. For instance, porous wood may be soaked in the soft resin and then by heat and pressure it is changed to the bakelite form and the wood comes out with a hard finish that may be given the brilliant polish of j.a.panese lacquer. Paper, cardboard, cloth, wood pulp, sawdust, asbestos and the like may be impregnated with the resin, producing tough and hard material suitable for various purposes. Bra.s.s work painted with it and then baked at 300 F. acquires a lacquered surface that is unaffected by soap. Forced in powder or sheet form into molds under a pressure of 1200 to 2000 pounds to the square inch it takes the most delicate impressions. Billiard b.a.l.l.s of bakelite are claimed to be better than ivory because, having no grain, they do not swell unequally with heat and humidity and so lose their sphericity. Pipestems and beads of bakelite have the clear brilliancy of amber and greater strength.

Fountain pens made of it are transparent so you can see how much ink you have left. A new and enlarging field for bakelite and allied products is the making of noiseless gears for automobiles and other machinery, also of air-plane propellers.

Celluloid is more plastic and elastic than bakelite. It is therefore more easily worked in sheets and small objects. Celluloid can be made perfectly transparent and colorless while bakelite is confined to the range between a clear amber and an opaque brown or black. On the other hand bakelite has the advantage in being tasteless, odorless, inert, insoluble and non-inflammable. This last quality and its high electrical resistance give bakelite its chief field of usefulness. Electricity was discovered by the Greeks, who found that amber (_electron_) when rubbed would pick up straws. This means simply that amber, like all such resinous substances, natural or artificial, is a non-conductor or di-electric and does not carry off and scatter the electricity collected on the surface by the friction. Bakelite is used in its liquid form for impregnating coils to keep the wires from shortcircuiting and in its solid form for commutators, magnetos, switch blocks, distributors, and all sorts of electrical apparatus for automobiles, telephones, wireless telegraphy, electric lighting, etc.

Bakelite, however, is only one of an indefinite number of such condensation products. As Baeyer said long ago: "It seems that all the aldehydes will, under suitable circ.u.mstances, unite with the aromatic hydrocarbons to form resins." So instead of phenol, other coal tar products such as cresol, naphthol or benzene itself may be used. The carbon links (-CH_{2}-, methylene) necessary to hook these carbon rings together may be obtained from other substances than the aldehydes, for instance from the amines, or ammonia derivatives. Three chemists, L.V. Kedman, A.J. Weith and F.P. Broek, working in 1910 on the Industrial Fellows.h.i.+ps of the late Robert Kennedy Duncan at the University of Kansas, developed a process using formin instead of formaldehyde. Formin--or, if you insist upon its full name, hexa-methylene-tetramine--is a sugar-like substance with a fish-like smell. This mixed with crystallized carbolic acid and slightly warmed melts to a golden liquid that sets on pouring into molds. It is still plastic and can be bent into any desired shape, but on further heating it becomes hard without the need of pressure. Ammonia is given off in this process instead of water which is the by-product in the case of formaldehyde. The product is similar to bakelite, exactly how similar is a question that the courts will have to decide. The inventors threatened to call it Phenyl-endeka-saligeno-saligenin, but, rightly fearing that this would interfere with its salability, they have named it "redmanol."

A phenolic condensation product closely related to bakelite and redmanol is condensite, the invention of Jonas Walter Aylesworth. Aylesworth was trained in what he referred to as "the greatest university of the world, the Edison laboratory." He entered this university at the age of nineteen at a salary of $3 a week, but Edison soon found that he had in his new boy an a.s.sistant who could stand being shut up in the laboratory working day and night as long as he could. After nine years of close a.s.sociation with Edison he set up a little laboratory in his own back yard to work out new plastics. He found that by acting on naphthalene--the moth-ball stuff--with chlorine he got a series of useful products called "halowaxes." The lower chlorinated products are oils, which may be used for impregnating paper or soft wood, making it non-inflammable and impregnable to water. If four atoms of chlorine enter the naphthalene molecule the product is a hard wax that rings like a metal.

Condensite is anhydrous and infusible, and like its rivals finds its chief employment in the insulation parts of electrical apparatus. The records of the Edison phonograph are made of it. So are the b.u.t.tons of our blue-jackets. The Government at the outbreak of the war ordered 40,000 goggles in condensite frames to protect the eyes of our gunners from the glare and acid fumes.

The various synthetics played an important part in the war. According to an ancient military pun the endurance of soldiers depends upon the strength of their soles. The new compound rubber soles were found useful in our army and the Germans attribute their success in making a little leather go a long way during the late war to the use of a new synthetic tanning material known as "neradol." There are various forms of this.

Some are phenolic condensation products of formaldehyde like those we have been considering, but some use coal-tar compounds having no phenol groups, such as naphthalene sulfonic acid. These are now being made in England under such names as "paradol," "cresyntan" and "syntan." They have the advantage of the natural tannins such as bark in that they are of known strength and can be varied to suit.

This very grasping compound, formaldehyde, will attack almost anything, even molecules many times its size. Gelatinous and alb.u.minous substances of all sorts are solidified by it. Glue, skimmed milk, blood, eggs, yeast, brewer's slops, may by this magic agent be rescued from waste and reappear in our b.u.t.tons, hairpins, roofing, phonographs, shoes or shoe-polish. The French have made great use of casein hardened by formaldehyde into what is known as "galalith" (i.e., milkstone). This is harder than celluloid and non-inflammable, but has the disadvantages of being more brittle and of absorbing moisture. A mixture of casein and celluloid has something of the merits of both.

The j.a.panese, as we should expect, are using the juice of the soy bean, familiar as a condiment to all who patronize chop-sueys or use Worcesters.h.i.+re sauce. The soy glucine coagulated by formalin gives a plastic said to be better and cheaper than celluloid. Its inventor, S.

Sato, of Sendai University, has named it, according to American precedent, "Satolite," and has organized a million-dollar Satolite Company at Mukojima.

The algin extracted from the Pacific kelp can be used as a rubber surrogate for water-proofing cloth. When combined with heavier alkaline bases it forms a tough and elastic substance that can be rolled into transparent sheets like celluloid or turned into b.u.t.tons and knife handles.

In Australia when the war shut off the supply of tin the Government commission appointed to devise means of preserving fruits recommended the use of cardboard containers varnished with "magramite." This is a name the Australians coined for synthetic resin made from phenol and formaldehyde like bakelite. Magramite dissolved in alcohol is painted on the cardboard cans and when these are stoved the coating becomes insoluble.

Tarasoff has made a series of condensation products from phenol and formaldehyde with the addition of sulfonated oils. These are formed by the action of sulfuric acid on coconut, castor, cottonseed or mineral oils. The products of this combination are white plastics, opaque, insoluble and infusible.

Since I am here chiefly concerned with "Creative Chemistry," that is, with the art of making substances not found in nature, I have not spoken of sh.e.l.lac, asphaltum, rosin, ozocerite and the innumerable gums, resins and waxes, animal, mineral and vegetable, that are used either by themselves or in combination with the synthetics. What particular "dope"

or "mud" is used to coat a canvas or form a telephone receiver is often hard to find out. The manufacturer finds secrecy safer than the patent office and the chemist of a rival establishment is apt to be baffled in his attempt to a.n.a.lyze and imitate. But we of the outside world are not concerned with this, though we are interested in the manifold applications of these new materials.

There seems to be no limit to these compounds and every week the journals report new processes and patents. But we must not allow the new ones to crowd out the remembrance of the oldest and most famous of the synthetic plasters, hard rubber, to which a separate chapter must be devoted.

VIII

THE RACE FOR RUBBER

There is one law that regulates all animate and inanimate things. It is formulated in various ways, for instance:

Running down a hill is easy. In Latin it reads, _facilis descensus Averni._ Herbert Spencer calls it the dissolution of definite coherent heterogeneity into indefinite incoherent h.o.m.ogeneity. Mother Goose expresses it in the fable of Humpty Dumpty, and the business man extracts the moral as, "You can't unscramble an egg." The theologian calls it the dogma of natural depravity. The physicist calls it the second law of thermodynamics. Clausius formulates it as "The entropy of the world tends toward a maximum." It is easier to smash up than to build up. Children find that this is true of their toys; the Bolsheviki have found that it is true of a civilization. So, too, the chemist knows a.n.a.lysis is easier than synthesis and that creative chemistry is the highest branch of his art.

This explains why chemists discovered how to take rubber apart over sixty years before they could find out how to put it together. The first is easy. Just put some raw rubber into a retort and heat it. If you can stand the odor you will observe the caoutchouc decomposing and a benzine-like liquid distilling over. This is called "isoprene." Any Freshman chemist could write the reaction for this operation. It is simply

C_{10}H_{16} --> 2C_{5}H_{8} caoutchouc isoprene

That is, one molecule of the gum splits up into two molecules of the liquid. It is just as easy to write the reaction in the reverse directions, as 2 isoprene--> 1 caoutchouc, but n.o.body could make it go in that direction. Yet it could be done. It had been done. But the man who did it did not know how he did it and could not do it again.

Professor Tilden in May, 1892, read a paper before the Birmingham Philosophical Society in which he said:

I was surprised a few weeks ago at finding the contents of the bottles containing isoprene from turpentine entirely changed in appearance. In place of a limpid, colorless liquid the bottles contained a dense syrup in which were floating several large ma.s.ses of a yellowish color. Upon examination this turned out to be India rubber.

But neither Professor Tilden nor any one else could repeat this accidental metamorphosis. It was tantalizing, for the world was willing to pay $2,000,000,000 a year for rubber and the forests of the Amazon and Congo were failing to meet the demand. A large share of these millions would have gone to any chemist who could find out how to make synthetic rubber and make it cheaply enough. With such a reward of fame and fortune the compet.i.tion among chemists was intense. It took the form of an international contest in which England and Germany were neck and neck.

[Ill.u.s.tration: Courtesy of the "India Rubber World."

What goes into rubber and what is made out of it]

The English, who had been beaten by the Germans in the dye business where they had the start, were determined not to lose in this. Prof.

W.H. Perkin, of Manchester University, was one of the most eager, for he was inspired by a personal grudge against the Germans as well as by patriotism and scientific zeal. It was his father who had, fifty years before, discovered mauve, the first of the anilin dyes, but England could not hold the business and its rich rewards went over to Germany.

So in 1909 a corps of chemists set to work under Professor Perkin in the Manchester laboratories to solve the problem of synthetic rubber. What reagent could be found that would reverse the reaction and convert the liquid isoprene into the solid rubber? It was discovered, by accident, we may say, but it should be understood that such advantageous accidents happen only to those who are working for them and know how to utilize them. In July, 1910, Dr. Matthews, who had charge of the research, set some isoprene to drying over metallic sodium, a common laboratory method of freeing a liquid from the last traces of water. In September he found that the flask was filled with a solid ma.s.s of real rubber instead of the volatile colorless liquid he had put into it.

Twenty years before the discovery would have been useless, for sodium was then a rare and costly metal, a little of it in a sealed gla.s.s tube being pa.s.sed around the chemistry cla.s.s once a year as a curiosity, or a tiny bit cut off and dropped in water to see what a fuss it made. But nowadays metallic sodium is cheaply produced by the aid of electricity.

The difficulty lay rather in the cost of the raw material, isoprene. In industrial chemistry it is not sufficient that a thing can be made; it must be made to pay. Isoprene could be obtained from turpentine, but this was too expensive and limited in supply. It would merely mean the destruction of pine forests instead of rubber forests. Starch was finally decided upon as the best material, since this can be obtained for about a cent a pound from potatoes, corn and many other sources.

Here, however, the chemist came to the end of his rope and had to call the bacteriologist to his aid. The splitting of the starch molecule is too big a job for man; only the lower organisms, the yeast plant, for example, know enough to do that. Owing perhaps to the _entente cordiale_ a French biologist was called into the combination, Professor Fernbach, of the Pasteur Inst.i.tute, and after eighteen months' hard work he discovered a process of fermentation by which a large amount of fusel oil can be obtained from any starchy stuff. Hitherto the aim in fermentation and distillation had been to obtain as small a proportion of fusel as possible, for fusel oil is a mixture of the heavier alcohols, all of them more poisonous and malodorous than common alcohol.

But here, as has often happened in the history of industrial chemistry, the by-product turned out to be more valuable than the product. From fusel oil by the use of chlorine isoprene can be prepared, so the chain was complete.

But meanwhile the Germans had been making equal progress. In 1905 Prof.

Karl Harries, of Berlin, found out the name of the caoutchouc molecule.

This discovery was to the chemists what the architect's plan of a house is to the builder. They knew then what they were trying to construct and could go about their task intelligently.

Mark Twain said that he could understand something about how astronomers could measure the distance of the planets, calculate their weights and so forth, but he never could see how they could find out their names even with the largest telescopes. This is a joke in astronomy but it is not in chemistry. For when the chemist finds out the structure of a compound he gives it a name which means that. The stuff came to be called "caoutchouc," because that was the way the Spaniards of Columbus's time caught the Indian word "cahuchu." When Dr. Priestley called it "India rubber" he told merely where it came from and what it was good for. But when Harries named it "1-5-dimethyl-cyclo-octadien-1-5" any chemist could draw a picture of it and give a guess as to how it could be made. Even a person without any knowledge of chemistry can get the main point of it by merely looking at this diagram:

C C C---C || || || | C--C C C--C C | | --> | | C C--C C C--C || || | || C C C---C