266 Mr. Wm. Thomson and Mr. F. Lewis on 



On the action of different Metals, Metallic Salts, Acids, 

 and Oxidising Agents on India-rubber. By William 

 Thomson, F. R.S.Ed., etc., and Frederick Lewis. 



{Received April 20th, 18^1.) 



A few years ago one of us studied the influence of 

 different oily and greasy matters on india-rubber.. {Journal 

 of the Soc. of Chemical Industry^ 29th December, 1885), 

 and at the last meeting of the British Association in Leeds 

 we called attention to the distinctive effect which both 

 metallic copper and all the salts of copper exercised on 

 india-rubber. In the present paper we have carried these 

 experiments further, with a view of obtaining more accurate 

 information as to the effect of copper and its salts, and also 

 that of other metals and their salts, and other agents, on 

 india-rubber. 



The method we adopted was to take a fine sheet of 

 india-rubber spread on paper and vulcanized by the cold 

 process with a mixture of chloride of sulphur dissolved in 

 bisulphide of carbon. By this arrangement it was easy to 

 tell the effect of different substances on the rubber ; on 

 breaking the paper between the fingers the fine sheet of 

 caoutchouc being left free so that it could be stretched, and 

 a fair idea obtained as to whether its elastic properties had 

 been damaged. 



Action of Metals on Rubber, 



The first series of experiments was made with different 

 metals reduced, by means of a file, to a fine state of 



