TRANSACTIONS OF SECTION B. 523 



3. Chemical Research in the Butch East Indies. By Dr. Gresiioff. 



4. The UtiJisaticyi of Nitrogen in Air by Plants. By T. Jamieson, F.I.C. 



M ONBA r, A UG UST 6. 

 The following Papers were read : — 



1. The Present Position of the Chemistry of Rubber. 

 By S. S. Pickles, M.Sc. — See Reports, p. 233. 



2. On the Constitution of Caoutchouc. By Professor C. D. Harries. 



If ozonised oxygen is passed into unsaturated hydrocarbons, a molecule of 

 ozone adds itself on at eacli double bond, and ozonides are formed. These are 

 explosive syrups, and in contact with water are decomposed into aldehydes, or 

 ketones, having smaller molecules, the disruption always taking place at the 

 double bond. At the same time the water which takes part in the reaction is 

 converted into hydrogen peroxide. The process can be expressed as follows : — 



RCH : CHY+Oj^R. GH-CHY + H.,0 = RCHO + OCHY+HjO.. 



1 I * 



o — o 

 \o/ 



Under certain circumstances peroxides also are formed, thus :— 



R, :C-CHY >R, :€<: | +OCHY. 





o — o 



By the application of this process to indiarubber and guttapercha it has been 

 found possible to elucidate with tolerable certainty their chemical nature. The 

 ozonide obtained in the case of rubber has the empirical formula C,oH,(;Og, thus 

 indicating that the molecule C,^,rii,. contained two double linkages. 



The molecular weight of this diozonide was found by the cryoscopic method 

 to be in accordance with the formula C,oH,|.Og. It is thus concluded that the 

 large molecule (Cl^,H,e).r is broken up into x molecules of C,oHjg. 



(C,„H, Ja; + ozone = a;C,„H,jOg, 



ind, according to this conception, indiarubber and guttapercha must be formed by 

 ihe polymerisation of the hydrocarbon Ci„H„,. The nature of this hydrocarbon 

 was ascertained as follows : The diozonide was decomposed with hot water or 

 steam, and the products of the decomposition were found to be (1) levulinic 

 aldehyde or levulinic acid, and (2) levulinic aldehyde diperoxide, a crystalline 

 body, C5H8O4, having probably the constitution — 



CH3-C.CHj-CHj.CH 



II II 



0=0=0 = 



On treatment with steam this latter body dissolves completely, passing into 

 levulinic aldehyde or levulinic acid, hydrogen peroxide being formed at the same 

 time. The above-mentioned bodies were found to be the only products of the 



