particularly for the purpose. The 

 nozzle of the hose is inserted in 

 the burrow, the rest of the open- 

 ing sealed with earth, and five or 

 six strokes of the pump handle 

 provide the initial distribution. 

 If gas is seen escaping from other 



holes, these, too, should be sealed, 

 or the rats will escape. The valve 

 on the bottom of the pump is then 

 switched over to "air," and the 

 gas is forced through the entire 

 burrow system. Burrows that 

 have been gassed should always 



nr ^ 





Figure 3.— Calcium cyanide is forced into rot burrows outside of buildings with a special stirrup 

 pump, OS one means of killing rats. 



