266 



THE INDIA RUBBER WORLD 



I February 1, 1915. 



on rubber splutions prefer to use the Ostwald viscosimeter, 



which is so little known in America that the dealers in labora- 

 tory supplies neither illustrate ni i it. 



•CONSTITUTION OF THE RUBBEK MOLECULE. 



I. i VS i "Armour Engineer," March, I'M.?, p. \t/>) has 



a thesis on the theoretical structure of the rubber molecule. 

 This article has attracted much attention in Europe. Ditmai 

 ("Kolloid Zeitung," July, 1913) gives four pages to a review 

 of this article. 



I illicit had very early shown that isoprene was methyl divinil, 

 as quoted by Weber, but several years ago Harris ("Bcrichte," 

 Vol: 38, pp. 1195 and -590). after a thorough investigation, con- 

 d that the rubber molecule was 1.5, di-methyl-cyclo- 

 ocfadien, 1.5. which maj be regarded as two molecules of iso- 

 prene united by their double bonds, forming the 8 carbon rim.;. 

 In the "Annales de Chimie." 1913, p. 395, and "Berichte," Vol. 

 ■46, p. 733. work i- described on the halides and hydro- 

 iniilcs ano o onides, from which conclusions are drawn 

 as to the above 8 carbon ring ami the differences in con- 

 struction between the artificial rubbers and the natural rub- 

 bers. ("Journal of the Society of Chemical Industry," 1913, pp. 

 203, 264, 372 and '*3: and "Chemical Abstracts," p. 2862 



\Y. Caspari i The India Rubber World, April, 1914) has writ- 

 ten mi the composite nature of crude rubber. Quite recently 

 ('Annales de Chimie." Vol. 406, 1914. p. 173; "Chemiker 

 Zeitung," No. 21, p. 1239. and "Gummi Zeitung," November 3, 

 1914, p. 168), Harries has contributed articles on the consti- 

 tution of caoutchouc and allied compounds. Lichtenberg 

 ("Gummi Zeitung," November 13. 1914. p. 168) has studied the 

 conversion products of the hydro-halogenides of caoutchouc 

 and their thermal dissociation. 



THE NATURALLY ACCOMPANYING SUBSTANCES IX 

 CAOUTCHOUC. 



When Weber wrote his work it was recognized that resins, 

 ash and nitrogenous matters always accompanied rubber and the 

 influence of the resins was recognized, but the idea that the 

 insoluble portion described was of any influence was scouted on 

 account of its small quantity. 



At the Eighth International Congress of Chemistry L. E. 

 Weber read a paper showing that the extraction of resins greatly 

 interfered with the vulcanization of rubber. (Vol. 9, p. 95. Re- 

 port of the Eighth Congress.) Clayton Beadle and H. P. Stevens 

 discussed this (Ibid., Vol. 25, p. 581) and confirmed Weber's state- 

 ments. G. H. Savage also commented on this subject (Ibid.. 

 Vol. 27, p. 71) and discussed the effect of litharge. 



THE INSOLUBLE CONSTITUENTS OF CAOUTCHOUC. 



Since the time above referred to the nature of the insoluble 

 constituent has been studied and its influence determined with 

 some degree of accuracy. Beadle and Stevens (The India Rub- 

 bf.r World, May, 1914, p. 400) have shown its influence. In the 

 "Journal of the Society of Chemical Engineers." December 16, 

 1913, there is a full account of their experiments. W. Caspari, 

 as cited above (The India Rubber World, April, 1914, p. 340), 

 has shown that the pectous portions are stronger than the non- 

 pectous portion. Newton W. Barritt, of the International Insti- 

 tute of Agriculture at Rome, has lately (The India Rubber 

 World. June, 1914. p. 507) discussed the proteins of rubber. 



Spence and Kratz have in connection with studies on viscosity 

 i Tut: India Rubber World, October, 1914, p. 18) isolated the 

 insoluble constituents and determined the amount of nitrogen 

 therein and described the isolation and characterization of the 

 soluble constituents. C>. Bernstein (The India Rubber World, 

 mb'er, 1914, p. 68) criticizes their work, claiming it is not 

 novel in methods used. Marguis and Heim (The India Rubber 

 World. November. 1914. p. 68) in the "Bulletin of the Society 

 of Chemistry." 1913, p. 862, have also worked on this problem. 

 W. Schmidts has also contributed to this subject. ("Journal of 

 the Society of Chemical Industry," 1913, p. 499.) 



RESINS. 



Sinn years ago the deresination of rubbers such as pontianak 

 and guayule was carried on in the United States to a consider- 

 able extent and the resins from them attracted quite a little at- 

 tention as possible substances for use in various arts (The India 

 Rubber Wobj d, May, 1909, p. 277). At that time little was known 

 as to the chemical composition of these resins, though they 

 had been experimented on considerably for industrial use. We 

 referred above to the part these resins were supposed to play 

 in vulcanizing. Since that time views have changed in many 

 cases Of laic several researches have been conducted upon 

 these resins to determine their chemical composition. 



M. EClassert ("ZeitschKff Analytischer Chimie." Vol. 26 i 

 471) has conducted quite an extensive research on samples of 

 resins from America, and while be does not seem to know 

 where they came from it is evident from the description that 

 I bey were extracted resins from pontianak and guayule. The 

 pontianak resins were both the granular kind, as extracted, and 

 the same resins fused. 



G. Hillen ("Archives de Pharmacie." 1913, p. 94) gives re- 

 sults of a fairly thorough analysis of pontianak and other 

 resins. The subject of the relation of resins to vulcanization 

 was discussed at the Eighth International Congress of Chem- 

 istry by L. E. Weber, Beadle and Stevens (Vol. 9, p. 71, Report 

 of the Eighth Congress I. J. G. Fol also gave the results of ex- 

 periments to determine the relation between the amount of resins 

 and viscosity. E. Marckwald {Ibid., Vol. 28, p. 69) stated that 

 according to his experiments there was no relation between the 

 viscosity and the amount of resins in Manihot rubber. F. W. 

 llinricbsen also took part in the discussion, and G. H. Savage 

 (.Ibid., p. 71) gave results of vulcanizing with resins and litharge. 

 LATEX AND COAGULATION. 



When the main portion of rubber used in commerce and 

 manufactures was produced from wild trees and vines the sub- 

 ject of coagulation of the latex or anything connected with the 

 latex received very little attention from chemists. The pro- 

 duction of the rubbers was usually so far from civilization and 

 the transportation and preservation of latex to a point where the 

 chemist could be reached was so difficult that little progress in 

 its study was made. At the Eighth International Congress of 

 Chemistry (Report. Vol. 9. p. 39) Clayton Beadle and H. P. 

 Stevens made a long report on work on latex which had been 

 preserved and sent to England. They concluded that latex 

 preserved with ammonia would, after dialysis, behave similarly 

 to fresh latex. Coagulation, they believed, whether partial or 

 complete, is brought about by the action of acid-reacting sub- 

 stances on the free globules only. They state that 0.15 per cent. 

 acetic acid will completely coagulate freshly dialized latex. 



In part 2 of their paper they give complete analyses of latex. 

 COAGULATION. 



The Para rubber gatherers developed without the help of 

 chemists a very good system of coagulating latex, and rendering 

 it antiseptic, merely by their crude smoking methods. The 

 modern chemist has succeeded in pointing out to the plantation 

 manager how he can get the same effect with practically the 

 same substances applied by more modern methods. Modern 

 coagulation by acetic acid is following the same lines as the 

 seringueiro with his smoke. The acetic acid used by the planta- 

 tion manager is made primarily from wood smoke. In addition, 

 it is becoming common to produce smoked sheet. 



Sidney Morgan (The India Rubber World, December, 1913. 

 p. 147) with Clayton Beadle and Stevens have given results of 

 many experiments in methods of coagulating and drying crepe 

 and their effects on the product. They found that in all cases the 

 use of sodium bi-sulphite improved the rubber and made pale 

 crepe. 



M. V. Cayla (Tile India Rubber World, December, 1913, p. 

 118) has recently given a long description of the Brazilian sys- 

 tem .A smoking to produce coagulation. 



Newton W. Barritt, in the "Journal of the Society of 



