Caoutchouc source

Source.—The common substance which is known as rubber is the product obtained by the coagulation of the juice or latex which is present, usually in the bark, but sometimes in the woody tissue, of certain tropical or sub-tropical trees, shrubs and vines. Gutta-percha is a variety of rubber differing in physical properties. The chemical individual present in rubber is a terpene hydrocarbon known as caoutchouc. 

While caoutchouc was first obtained by polymerizing isoprene it has been found that other hydrocarbons containing the buta i-ydi-ene group will likewise yield caoutchouc. Such hydrocarbons have been obtained from several sources, e.g., turpentiney petroleuniy coaly acetylene. Also compounds related to succinic acid, e.g., pyrotartaric acid (methyl succinic acid) are possible of transformation into isoprene. Levulinic acid, which is aceto propionic acid, CHa—CO—CH2—CH2—COOH, yields a cyclic sulphur compound, methyl-thiophen (p. 853), which, like methyl pyrrolidine, yields isoprene. Ethyl alcohol by conversion into acetone and then by aldol condensation with ethane yields 2-methyl buta 2-ene, CHa—C = CH—CHa which may be transformed... 

A great deal of work has been done of recent years on the process of vulcanization. Unfortunately the results of one experimenter often seem to contradict those of another consequently we have few undisputed facts upon which to base our theories. This want of accord among the experimental results is probably not due so much to inaccurate work as it is to the fact that raw caoutchouc is a complex product, varying in properties to a condderable degree with its source, method of preparation, a e, etc. A short summary and not an extended dis-cusdon of the two prindpal theories will be ven here. For a more comprehensive review of the subject the reader is referred to the original literature, or to Der Kautschuk by Ditmar. 

Another remarkable property of the block of purified caoutchouc occurred when it was stretched even farther. The block became hard and very tough. This form could be heated and the block returned to its initial shape and elasticity. It is now known that the phenomenon being observed is crystallization, but at the time it was noted and puzzled about. Rubber has been a source of amazement and amusement ever since its discovery. 

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