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 homogeneity. 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 analysis 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
C10H16 → 2C5H8
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 nobody 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 masses 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 competition among chemists was intense. It took the form of an international contest in which England and Germany were neck and neck.
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 mass 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 glass tube being passed around the chemistry class 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 Institute, 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:
isoprene turns into caoutchouc
I have dropped the 16 H's or hydrogen atoms of the formula for simplicity's sake. They simply hook on wherever they can. You will see that the isoprene consists of a chain of four carbon atoms (represented by the C's) with an extra carbon on the side. In the transformation of this colorless liquid into soft rubber two of the double linkages break and so permit the two chains of 4 C's to unite to form one ring of eight. If you have ever played ring-around-a-rosy you will get the idea. In Chapter IV I explained that the anilin dyes are built up upon the benzene ring of six carbon atoms. The rubber ring consists of eight at least and probably more. Any substance containing that peculiar carbon chain with two double links C=C-C=C can double up—polymerize, the chemist calls it—into a rubber-like substance. So we may have many kinds of rubber, some of which may prove to be more useful than that which happens to be found in nature.
With the structural formula of Harries as a clue chemists all over the world plunged into the problem with renewed hope. The famous Bayer dye works at Elberfeld took it up and there in August, 1909, Dr. Fritz Hofmann worked out a process for the converting of pure isoprene into rubber by heat. Then in 1910 Harries happened upon the same sodium reaction as Matthews, but when he came to get it patented he found that the Englishman had beaten him to the patent office by a few weeks.
This Anglo-German rivalry came to a dramatic climax in 1912 at the great hall of the College of the City of New York when Dr. Carl Duisberg, of the Elberfeld factory, delivered an address on the latest achievements of the chemical industry before the Eighth—and the last for a long time—International Congress of Applied Chemistry. Duisberg insisted upon talking in German, although more of his auditors would have understood him in English. He laid full emphasis upon German achievements and cast doubt upon the claim of "the Englishman Tilden" to have prepared artificial rubber in the eighties. Perkin, of Manchester, confronted him with his new process for making rubber from potatoes, but Duisberg countered by proudly displaying two automobile tires made of synthetic rubber with which he had made a thousand-mile run.
The intense antagonism between the British and German chemists at this congress was felt by all present, but we did not foresee that in two years from that date they would be engaged in manufacturing poison gas to fire at one another. It was, however, realized that more was at stake than personal reputation and national prestige. Under pressure of the new demand for automobiles the price of rubber jumped from $1.25 to $3 a pound in 1910, and millions had been invested in plantations. If Professor Perkin was right when he told the congress that by his process rubber could be made for less than 25 cents a pound it meant that these plantations would go the way of the indigo plantations when the Germans succeeded in making artificial indigo. If Dr. Duisberg was right when he told the congress that synthetic rubber would "certainly appear on the market in a very short time," it meant that Germany in war or peace would become independent of Brazil in the matter of rubber as she had become independent of Chile in the matter of nitrates.
As it turned out both scientists were too sanguine. Synthetic rubber has not proved capable of displacing natural rubber by underbidding it nor even of replacing natural rubber when this is shut out. When Germany was blockaded and the success of her armies depended on rubber, price was no object. Three Danish sailors who were caught by United States officials trying to smuggle dental rubber into Germany confessed that they had been selling it there for gas masks at $73 a pound. The German gas masks in the latter part of the war were made without rubber and were frail and leaky. They could not have withstood the new gases which American chemists were preparing on an unprecedented scale. Every scrap of old rubber in Germany was saved and worked over and over and diluted with fillers and surrogates to the limit of elasticity. Spring tires were substituted for pneumatics. So it is evident that the supply of synthetic rubber could not have been adequate or satisfactory. Neither, on the other hand, have the British made a success of the Perkin process, although they spent $200,000 on it in the first two years. But, of course, there was not the same necessity for it as in the case of Germany, for England had practically a monopoly of the world's supply of natural rubber either through owning plantations or controlling shipping. If rubber could not be manufactured profitably in Germany when the demand was imperative and price no consideration it can hardly be expected to compete with the natural under peace conditions.
The problem of synthetic rubber has then been solved scientifically but not industrially. It can be made but cannot be made to pay. The difficulty is to find a cheap enough material to start with. We can make rubber out of potatoes—but potatoes have other uses. It would require more land and more valuable land to raise the potatoes than to raise the rubber. We can get isoprene by the distillation of turpentine—but why not bleed a rubber tree as well as a pine tree? Turpentine is neither cheap nor abundant enough. Any kind of wood, sawdust for instance, can be utilized by converting the cellulose over into sugar and fermenting this to alcohol, but the process is not likely to prove profitable. Petroleum when cracked up to make gasoline gives isoprene or other double-bond compounds that go over into some form of rubber.
But the most interesting and most promising of all is the complete inorganic synthesis that dispenses with the aid of vegetation and starts with coal and lime. These heated together in the electric furnace form calcium carbide and this, as every automobilist knows, gives acetylene by contact with water. From this gas isoprene can be made and the isoprene converted into rubber by sodium, or acid or alkali or simple heating. Acetone, which is also made from acetylene, can be converted directly into rubber by fuming sulfuric acid. This seems to have been the process chiefly used by the Germans during the war. Several carbide factories were devoted to it. But the intermediate and by-products of the process, such as alcohol, acetic acid and acetone, were in as much demand for war purposes as rubber. The Germans made some rubber from pitch imported from Sweden. They also found a useful substitute in aluminum naphthenate made from Baku petroleum, for it is elastic and plastic and can be vulcanized.
So although rubber can be made in many different ways it is not profitable to make it in any of them. We have to rely still upon the natural product, but we can greatly improve upon the way nature produces it. When the call came for more rubber for the electrical and automobile industries the first attempt to increase the supply was to put pressure upon the natives to bring in more of the latex. As a consequence the trees were bled to death and sometimes also the natives. The Belgian atrocities in the Congo shocked the civilized world and at Putumayo on the upper Amazon the same cause produced the same horrible effects. But no matter what cruelty was practiced the tropical forests could not be made to yield a sufficient increase, so the cultivation of the rubber was begun by far-sighted men in Dutch Java, Sumatra and Borneo and in British Malaya and Ceylon.
Brazil, feeling secure in the possession of a natural monopoly, made no effort to compete with these parvenus. It cost about as much to gather rubber from the Amazon forests as it did to raise it on a Malay plantation, that is, 25 cents a pound. The Brazilian Government clapped on another 25 cents export duty and spent the money lavishly. In 1911 the treasury of Para took in $2,000,000 from the rubber tax and a good share of the money was spent on a magnificent new theater at Manaos—not on setting out rubber trees. The result of this rivalry between the collector and the cultivator is shown by the fact that in the decade 1907-1917 the world's output of plantation rubber increased from 1000 to 204,000 tons, while the output of wild rubber decreased from 68,000 to 53,000. Besides this the plantation rubber is a cleaner and more even product, carefully coagulated by acetic acid instead of being smoked over a forest fire. It comes in pale yellow sheets instead of big black balls loaded with the dirt or sticks and stones that the honest Indian sometimes adds to make a bigger lump. What's better, the man who milks the rubber trees on a plantation may live at home where he can be decently looked after. The agriculturist and the chemist may do what the philanthropist and statesman could not accomplish: put an end to the cruelties involved in the international struggle for "black gold."
The United States uses three-fourths of the world's rubber output and grows none of it. What is the use of tropical possessions if we do not make use of them? The Philippines could grow all our rubber and keep a $300,000,000 business under our flag. Santo Domingo, where rubber was first discovered, is now under our supervision and could be enriched by the industry. The Guianas, where the rubber tree was first studied, might be purchased. It is chiefly for lack of a definite colonial policy that our rubber industry, by far the largest in the world, has to be dependent upon foreign sources for all its raw materials. Because the Philippines are likely to be cast off at any moment, American manufacturers are placing their plantations in the Dutch or British possessions. The Goodyear Company has secured a concession of 20,000 acres near Medan in Dutch Sumatra.
While the United States is planning to relinquish its Pacific possessions the British have more than doubled their holdings in New Guinea by the acquisition of Kaiser Wilhelm's Land, good rubber country. The British Malay States in 1917 exported over $118,000,000 worth of plantation-grown rubber and could have sold more if shipping had not been short and production restricted. Fully 90 per cent. of the cultivated rubber is now grown in British colonies or on British plantations in the Dutch East Indies. To protect this monopoly an act has been passed preventing foreigners from buying more land in the Malay Peninsula. The Japanese have acquired there 50,000 acres, on which they are growing more than a million dollars' worth of rubber a year. The British Tropical Life says of the American invasion: "As America is so extremely wealthy Uncle Sam can well afford to continue to buy our rubber as he has been doing instead of coming in to produce rubber to reduce his competition as a buyer in the world's market." The Malaya estates calculate to pay a dividend of 20 per cent. on the investment with rubber selling at 30 cents a pound and every two cents additional on the price brings a further 3-1/2 per cent. dividend. The output is restricted by the Rubber Growers' Association so as to keep the price up to 50-70 cents. When the plantations first came into bearing in 1910 rubber was bringing nearly $3 a pound, and since it can be produced at less than 30 cents a pound we can imagine the profits of the early birds.
The fact that the world's rubber trade was in the control of Great Britain caused America great anxiety and financial loss in the early part of the war when the British Government, suspecting—not without reason—that some American rubber goods were getting into Germany through neutral nations, suddenly shut off our supply. This threatened to kill the fourth largest of our industries and it was only by the submission of American rubber dealers to the closest supervision and restriction by the British authorities that they were allowed to continue their business. Sir Francis Hopwood, in laying down these regulations, gave emphatic warning "that in case any manufacturer, importer or dealer came under suspicion his permits should be immediately revoked. Reinstatement will be slow and difficult. The British Government will cancel first and investigate afterward." Of course the British had a right to say under what conditions they should sell their rubber and we cannot blame them for taking such precautions to prevent its getting to their enemies, but it placed the United States in a humiliating position and if we had not been in sympathy with their side it would have aroused more resentment than it did. But it made evident the desirability of having at least part of our supply under our own control and, if possible, within our own country. Rubber is not rare in nature, for it is contained in almost every milky juice. Every country boy knows that he can get a self-feeding mucilage brush by cutting off a milkweed stalk. The only native source so far utilized is the guayule, which grows wild on the deserts of the Mexican and the American border. The plant was discovered in 1852 by Dr. J.M. Bigelow near Escondido Creek, Texas. Professor Asa Gray described it and named it Parthenium argentatum, or the silver Pallas. When chopped up and macerated guayule gives a satisfactory quality of caoutchouc in profitable amounts. In 1911 seven thousand tons of guayule were imported from Mexico; in 1917 only seventeen hundred tons. Why this falling off? Because the eager exploiters had killed the goose that laid the golden egg, or in plain language, pulled up the plant by the roots. Now guayule is being cultivated and is reaped instead of being uprooted. Experiments at the Tucson laboratory have recently removed the difficulty of getting the seed to germinate under cultivation. This seems the most promising of the home-grown plants and, until artificial rubber can be made profitable, gives us the only chance of being in part independent of oversea supply.
There are various other gums found in nature that can for some purposes be substituted for caoutchouc. Gutta percha, for instance, is pliable and tough though not very elastic. It becomes plastic by heat so it can be molded, but unlike rubber it cannot be hardened by heating with sulfur. A lump of gutta percha was brought from Java in 1766 and placed in a British museum, where it lay for nearly a hundred years before it occurred to anybody to do anything with it except to look at it. But a German electrician, Siemens, discovered in 1847 that gutta percha was valuable for insulating telegraph lines and it found extensive employment in submarine cables as well as for golf balls, and the like.
Balata, which is found in the forests of the Guianas, is between gutta percha and rubber, not so good for insulation but useful for shoe soles and machine belts. The bark of the tree is so thick that the latex does not run off like caoutchouc when the bark is cut. So the bark has to be cut off and squeezed in hand presses. Formerly this meant cutting down the tree, but now alternate strips of the bark are cut off and squeezed so the tree continues to live.
When Columbus discovered Santo Domingo he found the natives playing with balls made from the gum of the caoutchouc tree. The soldiers of Pizarro, when they conquered Inca-Land, adopted the Peruvian custom of smearing caoutchouc over their coats to keep out the rain. A French scientist, M. de la Condamine, who went to South America to measure the earth, came back in 1745 with some specimens of caoutchouc from Para as well as quinine from Peru. The vessel on which he returned, the brig Minerva, had a narrow escape from capture by an English cruiser, for Great Britain was jealous of any trespassing on her American sphere of influence. The Old World need not have waited for the discovery of the New, for the rubber tree grows wild in Annam as well as Brazil, but none of the Asiatics seems to have discovered any of the many uses of the juice that exudes from breaks in the bark.
The first practical use that was made of it gave it the name that has stuck to it in English ever since. Magellan announced in 1772 that it was good to remove pencil marks. A lump of it was sent over from France to Priestley, the clergyman chemist who discovered oxygen and was mobbed out of Manchester for being a republican and took refuge in Pennsylvania. He cut the lump into little cubes and gave them to his friends to eradicate their mistakes in writing or figuring. Then they asked him what the queer things were and he said that they were "India rubbers."
FOREST RUBBER
Compare this tropical tangle and gnarled trunk with the straight tree and cleared ground of the plantation. At the foot of the trunk are cups collecting rubber juice.
PLANTATION RUBBER
This spiral cut draws off the milk as completely and quickly as possible without harming the tree. The man is pulling off a strip of coagulated rubber that clogs it.
IN MAKING GARDEN HOSE THE RUBBER IS FORMED INTO A TUBE BY THE MACHINE ON THE RIGHT AND COILED ON THE TABLE TO THE LEFT
The Peruvian natives had used caoutchouc for water-proof clothing, shoes, bottles and syringes, but Europe was slow to take it up, for the stuff was too sticky and smelled too bad in hot weather to become fashionable in fastidious circles. In 1825 Mackintosh made his name immortal by putting a layer of rubber between two cloths.
A German chemist, Ludersdorf, discovered in 1832 that the gum could be hardened by treating it with sulfur dissolved in turpentine. But it was left to a Yankee inventor, Charles Goodyear, of Connecticut, to work out a practical solution of the problem. A friend of his, Hayward, told him that it had been revealed to him in a dream that sulfur would harden rubber, but unfortunately the angel or defunct chemist who inspired the vision failed to reveal the details of the process. So Hayward sold out his dream to Goodyear, who spent all his own money and all he could borrow from his friends trying to convert it into a reality. He worked for ten years on the problem before the "lucky accident" came to him. One day in 1839 he happened to drop on the hot stove of the kitchen that he used as a laboratory a mixture of caoutchouc and sulfur. To his surprise he saw the two substances fuse together into something new. Instead of the soft, tacky gum and the yellow, brittle brimstone he had the tough, stable, elastic solid that has done so much since to make our footing and wheeling safe, swift and noiseless. The gumshoes or galoshes that he was then enabled to make still go by the name of "rubbers" in this country, although we do not use them for pencil erasers.
Goodyear found that he could vary this "vulcanized rubber" at will. By adding a little more sulfur he got a hard substance which, however, could be softened by heat so as to be molded into any form wanted. Out of this "hard rubber" "vulcanite" or "ebonite" were made combs, hairpins, penholders and the like, and it has not yet been superseded for some purposes by any of its recent rivals, the synthetic resins.
The new form of rubber made by the Germans, methyl rubber, is said to be a superior substitute for the hard variety but not satisfactory for the soft. The electrical resistance of the synthetic product is 20 per cent, higher than the natural, so it is excellent for insulation, but it is inferior in elasticity. In the latter part of the war the methyl rubber was manufactured at the rate of 165 tons a month.
The first pneumatic tires, known then as "patent aerial wheels," were invented by Robert William Thomson of London in 1846. On the following year a carriage equipped with them was seen in the streets of New York City. But the pneumatic tire did not come into use until after 1888, when an Irish horse-doctor, John Boyd Dunlop, of Belfast, tied a rubber tube around the wheels of his little son's velocipede. Within seven years after that a $25,000,000 corporation was manufacturing Dunlop tires. Later America took the lead in this business. In 1913 the United States exported $3,000,000 worth of tires and tubes. In 1917 the American exports rose to $13,000,000, not counting what went to the Allies. The number of pneumatic tires sold in 1917 is estimated at 18,000,000, which at an average cost of $25 would amount to $450,000,000.
No matter how much synthetic rubber may be manufactured or how many rubber trees are set out there is no danger of glutting the market, for as the price falls the uses of rubber become more numerous. One can think of a thousand ways in which rubber could be used if it were only cheap enough. In the form of pads and springs and tires it would do much to render traffic noiseless. Even the elevated railroad and the subway might be opened to conversation, and the city made habitable for mild voiced and gentle folk. It would make one's step sure, noiseless and springy, whether it was used individualistically as rubber heels or collectivistically as carpeting and paving. In roofing and siding and paint it would make our buildings warmer and more durable. It would reduce the cost and permit the extension of electrical appliances of almost all kinds. In short, there is hardly any other material whose abundance would contribute more to our comfort and convenience. Noise is an automatic alarm indicating lost motion and wasted energy. Silence is economy and resiliency is superior to resistance. A gumshoe outlasts a hobnailed sole and a rubber tube full of air is better than a steel tire.