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



Action of Metallic Salts on Rubber, 



Saturated solutions of a number of metallic salts were 

 made and painted over part of each small sheet of 

 rubber (equivalent to about ij^ inches square), allowed 

 to dry, and put into the incubator as above described. 

 Along with each series several untreated small sheets of 

 the same rubber were exposed for comparison, because, after 

 some weeks, the pure rubber will itself become oxidised and 

 lose its elasticity. Some insoluble or difficultly soluble com- 

 pounds were also employed. These were mixed into thin 

 pastes with water and painted on to the rubber sheets. The 

 following substances entirely destroyed the rubber : — 



Copper Sulphate. 



„ Chloride. 



■„ Nitrate. 



„ Ferrocyanide. 



„ Oxide. 



„ Sulphide. 

 Arsenic Iodide. 



Silver Nitrate. 

 Strontium Chlorate. 

 Vanadium Chloride. 

 Red Oxide of Manganese. 

 Black „ „ 



Bismuth Chloride. 



The following substances considerably damaged the 

 elasticity of the rubber but did not entirely destroy it : — 



Ferrous Nitrate. 

 Sodium Nitrite. 



Uranium Nitrate. 

 Ammonium Vanadate. 



The following substances only slightly damaged the 

 elasticity of the rubber : — 



Lead Chromate. 

 Ferrous Sulphate. 

 Zinc Acetate. 

 ,, Chloride. 



Tin Peroxide. 



„ Perchloride. 

 Chromic Acid. 

 Lead Borate. 



The following substances were found to have no action 

 whatever on india-rubber : — 



