PROPERTIES OF GASES 



95 



air is pumped into the tank by means of a motor and a pump 

 and the pressure in the tank is regulated to 7 atmospheres, 



FIG. 58. Pneumatic Hammer. Used in chipping rough 

 metal off a fire box. 



the motor starting and stopping automatically. The air is con- 

 ducted through flexible tubes lined with materials capable of 



PIG. 59. Pneumatic Drill. Partly in section. 



withstanding this working pressure of 7 atmospheres. Figures 

 57, 58, and 59 show important types of pneumatic tools. 



