AMERICAN .July 20, 60 SCIENTIFIC 1912 Rubber Natural and Synthetic How Will Artificial Rubber Affect the Plantation ? Willy Hinrichsen, of the Koenigliches Material-Pruefungsamt, Berlin By Prof. F. the last few years the world's consumption of caout- have recently been taken out to cover processes designed N [The author of this article, Prof. Hinrichsen, has I OhOlIO has increased at an extraordinaryrate, indeed, so to reduce the cost of the raw material. Isoprene, itself, completed for the Koeniglichcs Material-Pruefung­ e�traordinary, that the supply has not been able to keep is obtained not simply from haa,ted caoutchouc but also samt what may well be regarded as a most thorough up wi th the demand. The following table statistically from turpentine oil and from certain components of coal study of natural rubber, artificia� rubber and rub­ summa.rizes this remarkable increase : tar (cresol). Naturally, for practical purposes the iso­ ber substitutes. For that reason his comments prene must be obtained from some other source than WorM Production and World Consumption of on the commercial possibilities of the synthetic caoutchouc. Caoutchouc. rubber discovered in Germany deserve more Rubber Substitutes. World, World than passitng attention. An entirely new signifi­ Years. Production Consumption cance and intercst has been added to the topic by Long before artificial rubber was successfully produced in Tons. in Tons. the recent authoritative announcement that a body various compounds had been discovered which had many 1899-190 0 53,348 48,352 .••.......... of English chemists have surmounted the last dif­ of the properties of rubber, but were chemically different 1900-1901............ 52,864 51,136 ficulties in the synthesis of rubber, and have placed from it. Many of these are compounds of oil, shellac 1901-1902............ 53,887 51,110 it upon what promises to be a sound commercial and similar substances. Such rubber substitutes, "fac­ 1902-1903..... ... 55,603 55,276. , basis. Prof. Hinrichsen's article was w,ritten be­ tices," the French call them, are obtained by treating 1903-1904 ............. 61,759 59,666 fore this announcement, and is published here in oils with sulphur chloride, in which case a white rubber­ 1904-1905..... , . : ... 68,879 , .', 65,083 like substance is obtained ; -Witli 'sulphur alone, in 1905-1906 ............ 67,999 62,754 its original form. The reader must supplement his inf�rmation by reference to our editorial ·page.· which case a brown imitation rubber produced. Mix­ 1906-1 901 . 74,023 68,173 is - , . tures of such oil, or sulphur compounds with caoutchouc ]907-1908 ............ 66,379 62,376 -EDITOR. ] have proved convenient and serviceable. They seem to 1908-1909 ............ 70,587 71,998 last longer than rubber. The imitations or factices 1909-1910 ............ 76,553 76,O�6 produce artificially a rubber which is chemically the same themselves, depending upon their process of manufac­ 1910-1911 ............ 79,305 74,082 as the substance obtained from the Bevea tree. Stated ture, are usually loose and brittle masses of a white or thus baldly the problem seems very simple. Yet more From this table it appears that the consumption of brown color, to be distinguished from rubber by their than a decade of arduous chemical research has been re­ rubber in the year 1908-1909 (the financial year being ready saponification ; in other words, they are easily quired before rubber was synthetically produced in the usually reckoned from July 1st to the following June attacked by lyes. laboratory. 30th) exceeded the production. Had it not been for In the patent literature of every country will be found Among the constituents of rubber which are split up large reserves of raw caoutchouc left over from previous descriptions of plastic masses made from glue, gelatine, by intense heat is a liquid which boils at a low tempera­ years, the commercial situation might have been alarm- cellulose and the like-all alleged to be perfect substi­ ture and which in odor and in boiling point closely resem- tutes for rubber. Some of these have proved of indus­ ing. ,bles ordinary ether. That substance is known as iso­ The Price of Raw Rubber. trial importance. Most of them are valueless because of prene and was discovered by Williams as far back as This unfavorable relation between production and their inferior elasticity. 1860. Indeed, isoprene proved to be a compound of consumption naturally resulted in a considerable rise in carbon and hydrogen in about the same proportions as Regenerated Rubber. the market price of rubber. The increase in price which they are found in rubber itself. Foremost among the substitutes for pure rubber may would have normally resulted would have been serious Bouchardat, in the course of a comprehensive investi­ be mentioned regenerated rubber obtained from refuse enough, but thanks to the stock jobber, rubber brought gation, found that isoprene, under given conditions, was articles of manufactured rubber. Because of the small 12 shillings 6 pence per pound in May, 1910. After that converted into ' a substance analogous to caoutchouc. supply of natural caoutchouc, the necessity of utilizing there was a drop. In June, 191 1 , the price of raw caout­ Other experimenters made the same observation later, the refuse of rubber factories had become almost pressing. chouc reached a minimum of less than 4 shillings. Then among them Tilden and Wallach. Frequently, however, According to authoritative estimates, the quantity of old came another increase. The prices that I have here the conversion failed to take place. Why? Because the rubber regenerated for the manufacture of rubber articles quoted are those for the best quality of Brazilian Para exact experimental conditions which governed the con­ surpasses the consumption of raw caoutchouc. Such re­ rubber. version of "isoprene into caoutchouc had not yet been as­ claimed rubber is no perfect substitute for new: It The payment of such fabulous sums for natural rubber gum. certained. The failures were so numerous that chemists has lost much of elasticity and strength' by the mechan­ stimulated efforts to produce rubber artificially, in suffi­ began to doubt the correctness of earlier observations. ical, physical and chemical processes to which it is sub­ cient quantities and at sufficiently low prices to compete It was not before 1909, when F. Hofmann and C. Cou­ jected Old rubber shoes, pneumatic tires and the like with Para gum. I take it that readers of the SCIENTIFIC � telle, two chemists in the employ of one of the larg constitute the raw material from which regenerated rub­ AMERICAN are more less familiar with the methods w 01' chemical works in Germany, found that absolutely pure ber is made. When reclaimed the rubber differs in a employed in obtaining natural rubber. Caoutchouc is isoprene is converted into a substance resembling caout­ marked degree from caoutchouc. found in the milky juice (latex) of certain plants, which chouc if heated under pressure with and without the in­ Every one knows at this late day that all rubber arti­ flows out when the bark is pierced. By proper treatment tervention of other substances. Independently of these cles must be vulcanized, in other words, that at certain this milk is converted into caoutchouc. separating In experimenters, C. Barries, at Kiel, discovered the same temperatures sulphur in some form must be added. or coagulating caoutchouc the action of heat or chemicals reaction while heating isoprene with aqetic acid. Although the actual chemical process that occurs when is most important. sulphur is thus added is not yet known with absolute Rubber Plantations. The Commercial Possibilities of Artificial Rubbe�. certainty, recent investigations show that part of the sul­ Because the production of natural gum is not sufficient These experiments have .solved the problem of pro­ phur flompounds are chemically fixed by the caoutchouc. to keep pace with the constantly increasiIig demand, the ducing rubber synthetically, but as yet only from a scien­ This "combined" sulphur, as it is called, is not elimin­ more so since whole trees are felled and other most ruth­ tific point of view. It I;I1ay here be added that if the ini­ ated from present regenerated material. In actual prac­ less methods are resorted to, caoutchouc producers have tial material be varied in quality and the experimental tice, the reclaiming or regenerating process destroys the for some years past carried on the cultivation of the rub­ conditions modified, a number of substances which re­ fabrics in the old rubber and converts the remaining vul­ ber tree on plantations. Their rubber may even now be semble caOutchouc can be obtained, which are not to be . canized rubber to a plastic form for further manipulation. considered the most promising competitor of the wild found in nature., There is no good reason why the sulphur combined tree. Enormous areas, especially in Asia (the Malay Naturally the business man 'asks : What is the prac­ with vulcanized rubber could not be removed, theoretical­ States, Ceylon, etc.), have been planted with caoutchouo tical value of this work? Is synthetic rubber merely a ly, at le st. Most rubber experts, however, have come to a trees. The growth of these trees is rapid, and the laboratory curiosity? Or, can it be produced in market­ the conclusion that the task is hopeless. amount of caoutchouc annually produced by plantations able quantities at a price to compete with Para gum? Some apprehension has been expressed lest the continual is constantly increasing. By careful study the most If artificial rubber is to take the place of the natural increase in the production of plantation rubber should favorable conditions for cultivation--especially the con­ product, it must be produced more cheaply than Para result in an over-production.