AMOUNT OF PROTEIN IN RUBBER 



55 



probable, however, that other compounds containing 

 nitrogen maj'- also be present. 



The amount of protein in latex derived from different 

 plants, and in the rubber prepared therefrom, shows con- 

 siderable variation, as in the case of the resin. The follow- 

 ing analyses made at the Imperial Institute wiU illustrate 

 the variation in the proportion of protein present in 

 different crude rubbers : 



These analyses show that the amount of protein present 

 in various rubbers may vary from 0' 1 per cent, in the case of 

 a specimen of Landolphia Hetidelofii sheet to no less than 

 20" 4 per cent, in a specimen of Ceara scrap rubber. Ceara 

 latex usually contains a large proportion of protein, the 

 bulk of which finds its way into the rubber if this is col- 

 lected in the form of scrap by the spontaneous coagulation 

 of the latex on the stem. If, however, Ceara rubber is 

 prepared in the form of biscuits by diluting the latex 

 and allowing it to stand until coagulation takes place, a 

 considerable amount of the protein remains behind in 

 the liquid. The rubber prepared in biscuit or sheet 

 from the latices of certain species of Landolphia is note- 

 worthy in containing a very small amount of protein, 

 much less in fact than is present in the finest plantation 

 Para rubber. 



Carbohydrates. — Small quantities of carboh3^drates 

 (inosite and its derivatives) have been isolated from 

 certain kinds of crude rubber from the Gaboon, Borneo, 

 and Madagascar, the amount usually present not ex- 

 ceeding 0"5 per cent. Recently, however, specimens of 

 Para rubber prepared by the Brazilian method at the 

 Botanic Gardens, Singapore, M^ere found on examination 

 at the Imperial Institute to contain from TO to 2' 7 per 

 cent, of a saccharine substance which was identified as 



