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:
