THE CHEMISTRY OF INDIARUBBER 511 



is produced in the plant, probably by reduction of the sugars 

 (principally pentoses), and that, in the nascent state, the above 

 complexes condense, forming ultimately the rubber molecule 

 (Ci Hi,;)x- In support of this hypothesis he instances the for- 

 mation of the furans from sugar (Fischer and Laycock), and 

 the fact that a-methyl-furan is obtained from beechwood tar, 

 probably by decomposition of the celluloses (Harries). 



a-Methyl-furan can easily be made to yield levulinic aldehyde, 

 and this, by reduction, may give the above pentadiene. 



For the present we are compelled to leave here the chemistry 

 of indiarubber. It is probable that the last word regarding the 

 constitution is not yet spoken, for there are several points which 

 are not satisfactorily explained by Harries' formula. The fact 

 that although several octacarbocyclic compounds are known, 

 none have been found to polymerise into elastic substances ; the 

 observation that, on distillation in a vacuum, only high-boiling 

 hydrocarbons are formed, most of which, judging from their 

 boiling points, have formulae at least C 2 oH 3 2 ; and the unsatis- 

 factory and indefinite assumption of the mode of polymerisation, 

 render further investigation necessary. 



