RUBBER PLANTING 219 



hydrogen is emitted during the process of combination. 

 The action probably gives rise to a series of addition- 

 products parallel with those arising during simple 

 vulcanisation with sulphur. The series would then 

 begin with (QHw)bSiCls and end with C 10 H 16 S 2 C1 3 . 

 The fact that the addition of large amounts of the 

 pure solvent leads to the extraction of S 2 C1 2 from 

 the vulcanised rubber is equally well explained on 

 the hypothesis of a reversible chemical action as it is 

 on the adsorption hypothesis. 



