iME. C. GEEVILLE WILLIAMS ON ISOPEENE AND CAOUTCHINE. 
255 
being alkaline, as with caoutchouc, is powerfully acid. The acid is volatile, and appears 
to belong to one of the lower members of the series C" H" O^. On neutralizing the acid 
fluid with potash or soda, the odour of a volatile base becomes very perceptible. 
The oily distillate, as with caoutchouc, consists principally of the thick uninviting 
fluid called by Bouchaedat ‘ heveene.’ I have not as yet minutely examined it, but I 
beheve it to bear a polymeric relation to caoutchine. 
The amount of isoprene in the crude distillate is very small, probably not more than 
flve per cent., and, as will readily be supposed with so volatile a fluid, much is lost in the 
subsequent puriflcation. It is this circumstance which has prevented me from examining 
it so closely as could be deshed. 
The caoutchine constitutes about twenty per cent, of the distillate ; it was sensibly less 
pure than that procured from caoutchouc, and more rectiflcations over sodium were 
necessary before it was obtained in a sufficiently pure state for analysis. This partly 
arises from the tenacious manner in which the volatile acids above alluded to adhere to 
it, and render treatment mth alkalies essential previous to rectification. It is also 
accompanied by what we are too much accustomed to vaguely term empyreumatic pro- 
ducts. These are of a readily oxidizable nature, and may be got rid of by rectification 
two or three times over hydrate of potash. 
The following is a brief summary of the results of the above investigation : — 
1. The isolation of isoprene, C‘”H®, the existence of which among the products of the 
destructive distillation of caoutchouc had not been proved. 
2. The production of an apparently definite oxide of the hydrocarbon by the 
agency of ozone spontaneously generated. 
3. The determination of the polymeric relation between isoprene and caoutchine. 
4. The conversion of turpentine and caoutchine into the hydruret of thymyle or 
cymole. 
5. The production of paracymole. 
6. The determination of the products of the destructive distillation of gutta percha. 
