INSECT CONTROL, IN FLOUR MILLS. 



17 



unless present in excessive quantities. In estimating the amount of 

 acid required it is sometimes convenient to know that 1 \ pints of acid 



Fig. 10. — Third floor of a flour mill, showing the proper arrangement of the 

 generators and the bags of cyanid for hydrocyanic-acid gas fumigation where 

 the bags are to be dropped by hand. (Dean.) 



by liquid measure is required for each pound of cyanid when the 

 following formula is used. 



183545°— 20 3 



