572 



SEC. 13. CHEMISTRY. 



passage of the gas is regulated by means of an air pump, connected with the 

 glass tube u by a tube of caoutchouc. 



The volume of gas submitted to experiment was measured in a glass 

 pipette, of which a drawing is given in Fig. 3. The capacity of the pipette 

 (290*8 sub-centimes) between the two marks b and c was estimated by cali- 

 bration with mercury. It was then welded to a glass tube of the form given 

 in the figure ; e is a reservoir of sulphuric acid with a syphon tube attached ; 

 d a cylinder containing water, in which the pipette a is immersed, and in 



