THE CHEMISTRY OF INDIARUBBER 507 



The action of strong nitric acid upon caoutchouc has from 

 time to time been observed, and various results have been 

 recorded. Recently R. Ditmar 1 has gone into the question 

 systematically, and has been fortunate in obtaining a definite 

 compound by this treatment. The compound produced was 

 shown to have the formula C 10 H 12 N 2 O 6 , and to be a dinitro- 

 mono-carboxylic acid, probably dinitrohydrocumic acid. 



The treatment with nitric acid is, however, somewhat severe, 

 and it is possible that the formation of a six-carbon-ringed body 

 of this nature may be due to a secondary reaction. 



Action of Gases on Caoutchouc 



(a) Nitrous Fumes. — On passing nitrous fumes, obtained by 

 the action of nitric acid upon arsenious oxide, through light 

 petroleum in which rubber was suspended, Harries 2 obtained a 

 colloidal mass which rapidly changed into a yellow amorphous 

 substance. It was found, by analysis and molecular weight 

 determination, to have the formula CmH^O^Njo. 



By varying the conditions other nitrosites were also ob- 

 tained, 3 one of which (nitrosite " C ") is a yellow compound 

 having the formula C 2 oH 30 N fi On. An interesting point about this 

 nitrosite is that it can also be obtained from the product of 

 polymerisation of the hydrocarbon myrcene, which is found 

 occurring naturally in Bay oil. As myrcene is an open-chained 

 hydrocarbon, Harries, at first, considered this fact as favourable 

 to the idea that rubber was also an open-chained unsaturated 

 hydrocarbon. 



(b) Nitrogen Dioxide. — Weber 4 found that on passing dry 

 nitrogen dioxide gas, prepared by heating lead nitrate, through 

 a solution of Para rubber in benzene, a coherent mass separated 

 out, which, after washing and purification, was obtained as a 

 straw-coloured powder. This, on analysis, gave figures corre- 

 sponding to the formula C 10 Hi G N 2 O 4 . Other investigators 5 have, 

 however, been unable to isolate a compound of this composition. 

 The substances generally obtained more nearly agree with the 

 formula C 10 H 15 N 3 O 7 or C 20 H3oN 6 O u , the same as that of Harries' 

 nitrosite "C." 



1 Ber. f 35), 1902, pp. 1 401 -2 ; Monatshefte (25), p. 464. 



2 Ber. (34), 1 90 1, p. 2991. 



3 Ber. (35), p. 3256. 



4 Ber. (35), p. 1947. 



5 Harries, Ber. (38), pp. 87-90 ; Alexander, Ber. (38), pp. 181-4. 



