16 



BULLETIN 872, IT. S. DEPARTMENT OF AGRICULTURE. 



frequently has a milky white color, especially at the bottom of the 

 drum, due to the presence of sulphate of iron resulting from the 



Fig. 9. — Second 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.) 



action of the acid upon iron either before or after the acid is placed 

 in the drum. This sediment does not affect the value of the acid 



