42 THE ROYAL SOCIETY OF CANADA 



measured the amount of carbon dioxide formed in the oxidation and 

 found that about 5% of the rubber was oxidized to carbon dioxide. 

 It seems, then, that there is an isoprene group which is readily oxidized 

 by permanganate partly to a water soluble acid and partly to carbon 

 dioxide. The hydrogen dioxide oxidation leaves some of this unstable 

 C30H48O unattacked. The probable mechanism of these changes and 

 the constitution of the C30H48 molecule will be discussed presently 

 in this paper. 



The material insoluble in ether was dissolved in a small amount 

 of carbon tetrachloride and precipitated by methyl alcohol, washed 

 and dried at room temperature in a vacuum to constant weight. 

 This was a sticky mass which had a resin like odour. There was only 

 enough material for a single analysis. 



On heating some of the above ether soluble compound to 100° 

 it became partially insoluble in ether. Whether this ether insoluble 

 part is the same as the ether insoluble compound whose analysis has 

 just been given is not known. It will be investigated later. 



Action of Oxygen of the Air on Rubber. — Experimental Work by R. R. 

 McLaughlin and R. R. Parker. 



About 300 g. of resin-free rubber was rolled out into very thin 

 sheets and suspended in frames in direct sunlight for three months. 

 It was then extracted with acetone for two days and the acetone 

 extract was evaporated at room temperature. Approximately 30% 

 of the rubber had resinified. It was found that a separation of the 

 resin could be accomplished with carbon bisulphide. The whole of 

 the resin was extracted at room temperature with carbon bisulphide 

 and filtered at the pump, leaving a residue. The carbon bisulphide 

 solution was evaporated at room temperature and the residue so 

 obtained was dissolved in acetone, using a large amount of solvent to 

 facilitate filtration and the whole filtered. This solution was evapor- 

 ated at room temperature to a small bulk and the compound pre- 

 cipitated with methyl alcohol. This was filtered and dried to constant 

 weight under suction. This gave a tough rubbery substance. 



