230 RUBBER AND 



Various other simple articles are cut from rubber 

 which has already been vulcanised. Rubber rings, for 

 example, are sliced off the ends of vulcanised tubes. 



Rubber Solution. 



A large variety of objects is manufactured by 

 dipping prepared fabrics in rubber solution. The sol- 

 vents chiefly employed are benzene and mineral 

 naphtha. The rubber is rendered more readily soluble 

 by undergoing previous mastication. Rubber shoes 

 and galoshes are dipped by dozens at a time in tanks 

 of solution and afterwards allowed to. dry. Teats for 

 feeding bottles are made by dipping glass moulds 

 repeatedly in clear solution, with intervals for drying. 

 Some of the smaller articles prepared in this way are 

 vulcanised by the cold process, but for larger objects 

 the sulphur required for vulcanisation is incorporated 

 in the solution. For repairing motor tyres a quick- 

 vulcanising mixture is employed, in order that the rest 

 of the tyre may not be damaged by the heat required 

 for vulcanising the mended area. 



Vulcanisation. 



H. C. Pearson has pointed out that the natives of 

 some parts of the Amazon districts are accustomed 

 to mix sulphur with the latex of Hevea before employing 

 it for waterproofing. True combination between the 

 rubber and the sulphur, however, apparently only occurs 



