516 



IV. " On Isoprene and Caoutchine." By C. GREVILLE WIL- 

 LIAMS, Esq. Communicated by Professor STOKES, Sec. R.S. 

 Received June 4, 1860. 



(Abstract.) 



This paper contains the results of the investigation of the two prin- 

 cipal hydrocarbons produced by destructive distillation of caout- 

 chouc and gutta percha. 



Isoprene. 



This substance is an exceedingly volatile hydrocarbon, boiling 

 between 37 and 38 C. ; after repeated cohobations over sodium, it 

 was distilled and analysed. The numbers obtained as the mean of 

 five analyses were as follows : 



Experiment. Calculation. 



Carbon . . . 88^0 '5" ) 60 88'2 



Hydrogen . . 12-1 H 8 8 11 '8 



68 100-0 



Three of the specimens were from caoutchouc and two from gutta 

 percha. The vapour-density was found to be at 58 C. 2*40. Theory 

 requires, for C 10 H 8 =4 volumes, 2'35. The density of the liquid 

 was 0-6823 at 20 C. 



Action of Atmospheric Oxygen upon Isoprene. 



Isoprene, exposed to the air for some months, thickens and acquires 

 powerful bleaching properties owing to the absorption of ozone. On 

 distilling the ozonized liquid, a violent reaction takes place between 

 the ozone and the hydrocarbon. All the unaltered hydrocarbon distils 

 away, and the contents of the retort suddenly solidify to a pure, 

 white, amorphous mass, yielding the annexed result on combustion : 



Experiment. Calculation. 



76 100-00 



This directly-formed oxide of a hydrocarbon is unique, as regards 

 both its formula and mode of production. 



