252 EEPOETS ON THE STATE OF SCIENCE. 



leaving oxalic acid and a substance of a fatty nature. The solution of 

 caoutchouc in strong nitric acid gave, on diluting with water, a yellow 

 precipitate which was soluble in alcohol, acids and alkalies and took fire 

 at 100^ 



Wm. Roxburgh ', on treating rubber from Urceola elastica with nitric 

 acid obtained a yellow non-elastic mass. 



Schwanert "^ stated that strong nitric acid attacked rubber vigorously, 

 forming at first a yellow body, which was subsequently decomposed into 

 nitrogen, carbonic acid, and a fatty body. 



Terry,^ on treating caoutchouc with dilute nitric acid, produced a 

 nitrated body with explosive properties having the composition C 50-50 per 

 cent, H 6-13 per cent., O 37-94 per cent., N 5-43 per cent. 



E,. Ditmar,'' by the action of strong nitric acid upon caoutchouc, 

 obtained a yellow substance the formula of which, CmHiaNjOg, was 

 arrived at by analysis and confirmed by a molecular weight determination. 

 The substance was shown to be a monobasic acid, was soluble in alkalies, 

 and was precipitated from such solution by acids. On heating it began to 

 sinter at 142°-143° C, and at a higher temperature it was decomposed. 



This result was confirmed by Harries,^ who also examined the product 

 of direct oxidation of Para rubber. 



The compound CioHioN.^Og was further examined by R. Ditmar in 

 1904," who showed that it is probably 3 : 6 or 5 : 6 dinitro-hydrocuminic 

 acid. The alkali salts are red amorphous substances, CioHnOjN.^M, and 

 the methyl ester, CgH, lO^N.COOMe, is a red powder. The acetylanhy- 

 drideC9H,,04N2COOAc, melting-point 72°, is also an orange-red powder. 



On heating the dinitro compound at 100° in a sealed tube with 

 stannous chloride and hydrochloric acid, it is reduced to diamino-dihydro 

 jD-cuniinic acid. 



Torrey ^ proposed a quantitative colour test for the estimation of caout- 

 chouc depending on the action of nitric acid followed by the addition of 

 alkali. The chemical reactions involved were not understood, however, 

 and no definite compounds were isolated. 



Action of Nitrous Fumes. 



By suspending rubber in light petroleum and passing a rapid stream 

 of nitrous fumes (obtained by the action of nitric acid and arsenious oxide) 

 through the liquid. Harries obtained a colloidal mass which changed into 

 a golden yellow amorphous compound.^ The compound was soluble in 

 ethyl acetate but insoluble in ether. Analysis and molecular weight 

 determination indicated the formula CiuHg-jOoiNn,. It was soluble in 

 alkalies and was precipitated from solution by acids. In 1902^ the same 

 chemist passed dry gaseous nitrous acid (obtained as before) through a 

 benzene solution of Para rubber. A colloidal precipitate separated out 

 which was insoluble in all reagents except pyridine and aniline, which 

 appeared to decompose it. This was termed nitrosite a. 



When this nitrosite is further treated with nitrous fumes it is 

 changed into a yellow compound (nitrosite h) soluble in ethyl alcohol, 

 acetone or alkalies. It reduces Fehling's solution and decomposes at 



« See Crell, Ann. d. Chem., 2, 223 (1801). ' ^ Ann., 128, p. 123. 



3 J. S. C. I, 1892, p. 971. ' Ber., 35, 1902, 1401-2. * Ber., 35, 3256. 



« Monaisch., 25, 464. ' Indiaruhher Journal, 1905, pp. 417-418. 



» Ber., 84, 1901, 2991. » Ber., 35, 3256. 



