208 MACHINE FOR VULCANIZING 



been patented by me. It is very simple in its 

 construction, and entirely free from danger. The 

 air rises from the bottom, or may descend by a 

 down draught, which is the better process, and it 

 becomes rarefied and gradually heated through 

 the apparatus. This, in point of fact, is the true 

 automatic principle. The air, being perfectly 

 equalized, will not singe or burn 'anything. There 

 is not that process which is called torrefaction, 

 taking place. The heat is gradual, and the 

 moisture of the atmosphere is taken up with it, 

 and the consequence is, that when the heat has 

 been brought up to 300° or to 310°, a paper label 

 placed in the apparatus has not been so much as 

 singed, and yet the vulcanite piece made has been 

 perfectly vulcanized. So far as the application of 

 heat, therefore, is concerned, I believe that dry 

 heat is virtually the best. I don't say it because 

 I produce these apparatus, and I wish that to be 

 distinctly understood. Nor do I speak of any 

 particular machine, but of the principle of the 

 combined action of hydrogen with the sulphur in 

 india-rubber ; and it is an acknowledged principle, 

 that in the process where the cellular condition is 

 produced in the rubber, that it is owing to the 

 presence of hydrogen in combination with the 

 sulphur. But with my application of dry heat, 

 only the moisture of the atmosphere is taken up 

 in sufficient quantity to obtain the heat necessary 

 to produce a sound base. I have always found. 



