574 



SEC. 13* ^CHEMISTRY. 



"between the cylinder and reservoir may at pleasure be made or cut off. In 

 the reservoir 6 a small iron tube d is inserted, connected by a tube of 

 caoutchouc with a forcing pump firmly fixed to the table on which the 

 apparatus is placed. By means of this forcing pump the air contained in the 

 tipper part of the reservoir may be compressed, and any required pressure put 

 upon the mercury contained in it. The cylinder a is cemented by means of 

 a resinous cement into two steel caps, e and/ 1 ; the lower cap f is screwed 

 firmly upon the support of the apparatus, which is made of iron. The 

 cylinder is connected by means of a channel cut in the lower part of the steel 

 cap f and continued through the iron frame, with a glass tube g, which is 



FIG . 4- . 



