APPARATUS, MATERIAL, AND REAGENTS. 37 



and roof jacketed with felt. Water fills the inter- 

 space between the walls, 

 and on the roof are two 

 apertures, one for a gas 

 regulator, and the other 

 for a thermometer. In 

 front, the chest is closed 

 in by a sheet of felt, a 

 glass door, and a sliding 

 glass panel. The appa- 

 ratus can be suspended 

 on the wall or supported 

 on legs, and is heated 

 from below by means of 

 protected burners. 

 The gas should pass 



FIG. 2i. BABES' INCUUATOR. 



first through a pressure- 

 regulator, and then through a thermo-regulator to 

 the burners. 



Moitessier's Gas-pressure Regulator. This 

 apparatus is best explained by reference to the 

 diagram (Fig. 19). In the bottom of the cylinder A 

 are the entrance (K) and exit (/) gas tubes. The 

 tap (m) regulates the size of the flame. The cover 

 (n n) roofs in the cylinder A. The bell (B) supports 

 by means of e and/" the ball valve d, which lies in the 

 cover cc. The gas, entering by k, passes through 

 the valve d, and is thence conducted by the tube a 

 to the tube /. The bell B and the weighted dish 

 h are screwed on to the connecting rod g. To 

 diminish as much as possible the friction of g in 



