72 



NATURE 



[March 17, 1910 



a substitute for rubber in very hard articles, we may 

 mention the interesting material, " bakelite," recently 

 introduced by Dr. L. H. Baekeland. It is a condensa- 

 tion-product of formaldehyde and phenol, which can 

 be moulded as desired, and afterwards hardened. 



In what sense are the foregoing articles and their 

 likes to be considered as "substitutes" for rubber? 

 Some persons are disposed to deny them any right to 

 the title, and would look upon them as mere adul- 

 terants whenever used partially to replace rubber in 

 what would otherwise be an all-rubber article. Others 

 admit, though sometimes grudgingly, that there is a 

 place which such substitutes can usefully fill. Much 

 depends on what the article is sold as, and on what 

 use it is to be put to. Not all the special qualities of 

 rubber are wanted in all the products for which it is 

 employed. A door-mat is one thing, a bicycle tyre 

 quite another. Where a high degree of elasticity is 

 not really needed, as, for instance, in waterproof goods 

 and electrical insulating work, there is a legitimate 

 field for substitutes which may serve the required pur- 

 pose. Even here they may not be equal to rubber, but 

 they find their justification in their lower cost. After 

 all, we do not need razors to cut sticks with. 



It may be said at once that no substitute is equal to 

 rubber in every respect. Chemically, the latter is a 

 ver\' inert substance — much more so than the substi- 

 tutes. Hence, even if the latter were not otherwise 

 inferior, they would be less durable than rubber under 

 certain conditions. They are nearly all acted upon 

 more or less readily in circumstances where rubber 

 remains unharmed. The modified oils, in fact, are still 

 oils in the sense that they remain glycerides, decom- 

 posable by alkalies, as also by steam under pressure. 

 If used for articles exposed to these agencies, they 

 fail in durability, whatever their excellences other- 

 wise. 



The fact that substitutes of this class are readily 

 saponifiable by alkali makes it an easy matter to detect 

 them by analysis when compounded with true rubber. 

 As a rule, the proportion of substitute used is from 5 

 to 25 per cent., and even the smaller quantity is 

 recognisable. 



Of the composite rubbers (or "artificial rubbers," 

 as they are sometimes called), one preparation, which 

 has been made in quantity, and is said to be excellent 

 for many purposes, has for its basis Guayule rubber in- 

 corporated with certain gums. Another such article is 

 compounded of natural rubber and some other sub- 

 stance of vegetable origin, probably a latex or a gum, 

 reputed to contain the same chemical elements as 

 rubber and in much the same proportion. Such 

 articles are, of course, only partially "substitutes" for 

 rubber, and their cost rises with that of the latter 

 ingredient. Moreover, if any very large demand for 

 them arose, there is always the possibility that the 

 supply of gums and latices would become insufficient, 

 and the advantage of lower cost would thus tend to 

 disappear. 



Coming now to true synthetic rubber; a question 

 often asked is whether there exists any probability of 

 such an article being manufactured and displacing 

 natural rubber, either wholly or to any large extent. 

 Will rubber plantations go the way of madder fields 

 and indigo cultivation? Well, the future is on the 

 knees of the gods. In the face of the precedents just 

 mentioned, to say nothing of others, he would be a 

 bold man who would venture to say that even the best 

 quality of rubber may not some day be made on a 

 commercial scale from cheaper materials such as beet 

 sugar and calcium carbide. But the day is not yet. 

 There are beginnings; there are clear indications of 

 the direction in which to proceed; there is distinct 

 NO. 2107, VOL. 83] 



progress to note. But there is still some distance to 

 go, and the end of the journey may not be even in 

 sight. 



India-rubber chemically is essentially a polymerised 

 terpene. An article patented some time ago, and 

 named " turpentine rubber," appears to foreshadow a 

 synthesis of true rubber. Turpentine is a mixture of 

 terpenes, and the article in question was to be obtained 

 by passing turpentine through a hot tube, and treat- 

 ing the resulting vapours with hydrochloric acid. The 

 result is a solid condensation-product ; and the idea at 

 the base of the process appears to be the production of 

 polymerised terpenes having some of the elastic pro- 

 perties of rubber. 



A more promising, because a more scientific way, 

 is that outlined in Heinemann's patent No. 21,772 of 

 1907. Here a true synthesis is attempted. It is based 

 upon the well-known fact that rubber is probably a 

 polymer of the semi-terpene isoprene. The first step 

 is the production of the unsaturated hydrocarbon 

 divinyl, CH^ : CH.CH : CH^. This is obtained by 

 passing mixed acetylene and ethylene gases through a 

 heated tube. With methyl chloride, divinyl yields 

 isoprene [methyl divinyl, CHj : C(CH3).CH : CHj] ; 

 and the isoprene on treatment with strong hydro- 

 chloric acid is converted by a union of molecules into 

 a substance closely resembling caoutchouc, if not 

 identical with it. The raw materials, so to speak, are 

 thus acetylene, ethylene, and methyl chloride, which 

 are themselves obtained by any of the ordinary 

 methods, e.g. from calcium carbide, alcohol, and beet 

 sugar residues respectively. 



The question is, can this or some other compara- 

 tively simple synthesis, theoretically quite possible as 

 a laboratory operation, be translated into a practicable 

 and profitable mode of manufacture on a large scale? 

 One of the first doubts to arise is whether the synthe- 

 sised caoutchouc will have the physical properties of 

 natural rubber; or whether these, by any course of 

 treatment, can be imparted to it. This doubt resolved, 

 there comes the question of economical production in 

 competition with the natural product. Much time and 

 thought have been spent on the problem of synthetic 

 rubber, and it is safe to conclude that there will yet b" 

 many a headache before it is solved. Judging cy 

 what is known to have been done rather than by the 

 promises, owners of rubber plantations may for the 

 present sleep peacefully in their beds. 



C. SiMMONDS. 



REPORT OF THE ROYAL COMMISSION ON 



CANALS. 



THE Royal Commission on Canals and Inland Navi- 

 gation, the final report of which has recently 

 been issued, was appointed in March, 1906, and con- 

 sisted of nineteen members. Lord Shuttleworth being 

 chairman. Their instructions were to inquire into the 

 present condition and financial position of the inland 

 waterways of the United Kingdom ; to report as to the 

 causes which have operated to prevent the carrying 

 out of improvements by private enterprise ; as to 

 improvements desirable in order to complete a through 

 communication by water between the centres of 

 commercial industry, and with the sea ; the prospect 

 of benefit to the trade of the country compatible with 

 a reasonable return on the probable cost; the ex- 

 pediency of canals being acquired by public bodies ; 

 and the methods by which funds could be provided 

 for their purchase and improvement. 



Seven reports and returns have already been issued, 

 and there are four more to follow, including that on 

 the Irish waterways. 



