k 



TUFTEDSPONGE. 187 



SPONGE. 



During the process of vulcanizing, the blistering of the 

 gum presented originally an obstacle to the art which at dif- 

 ferent times it seemed impossible to overcome. It was the 

 occasion of great loss and hinderance, both to the inventor and 

 the licensees who first engaged in the manufacture. This cir- 

 cumstance led to the production of the substance now called 

 gum-elastic sponge. After the cause of the blistering was 

 found to be owing to gases generated in the gum under certain 

 circumstances, it became necessary only to compound the gum 

 with such substances as would generate the gases freely, so as to 

 make the whole mass a sponge. Subsequently the effect of the 

 gases was to produce great irregularity in the shape of the gum 

 that was sponged, so that no particular form could be given to 

 it ; but on resorting to the expedient of heating in moulds, as in 

 the case of hollow-ware, it is now made to assume any form 

 which is desired, and any degree of porousness, whether of fine 

 or coarse texture, which has given rise to many useful applica- 

 tions of the article, among the most important of which may be 

 specified horse-collars, saddle and harness pads, corks, clothes 

 brushes, cushions, toys, &c. In order to form these articles with 

 a smooth surface they are coated with a sheet of elastic compound 

 previous to being vulcanized. This substance will be found ex- 

 ceedingly durable for any purpose to which it may be applied. 



