91 



to the fall of temperature when water vapor is driven from a salt 

 solution. 



In conclusion, it seems that manganese dioxide serves for more than 

 a distributer of heat, that it has a catalytic effect upon the potassium 

 chlorate, permitting the oxygen to be liberated at a much lower tem- 

 perature than when potassium chlorate is used alone. Powdered silica, 

 sand, and Venetian red do not produce this effect, at least not to the 

 same extent, at low temperatures, as black oxide of manganese. 



