502 THE SMALL GRAINS 



acid gas requires 2 to 3 days, and the long shut-down of 

 the mill and additional cost of the material is a consider- 

 able expense, besides the element of danger to the opera- 

 tor; while the heat can be applied from a Saturday 

 evening to Monday morning with no loss of time, little 

 expense, and no danger. (4) Any mill with sufficient 

 radiation to heat it in winter to 70 can readily be heated 

 in summer to a temperature of 118 to 122. (5) With 

 the heat method there is no injury to the floors, belts, or 

 mill machinery, and no danger from fire. 



548. Fumigation with hydrocyanic acid gas. This 

 method has been found very effective in eradicating the 

 Mediterranean flour moth. All stages of this moth, if 

 not covered with more than one inch of flour, yield to 

 the gas. Therefore in mills or other buildings infested 

 with this moth, where the heating system is not of a kind 

 to furnish sufficient heat, the hydrocyanic acid gas treat- 

 ment is to be recommended. The formula for preparing 

 the gas is as follows : 



Sodium cyanid (129-130 per cent) 3 pounds 

 Sulfuric acid (best commercial grade) 4^ pints 

 Water 9 pints 



Four-gallon stone jars are used in which to place the 

 water and sulfuric acid. The 3 pounds of sodium cyanid 

 are placed in a double manila paper sack, at the side of 

 each jar, and at the proper time are to be dropped into 

 the jar. Inside measurements should be made to de- 

 termine accurately the number of cubic feet in each 

 story of the building to be treated. A plan should be 

 prepared for the guidance of the operator, showing 

 the exact number of jars and the required quantity 

 of chemicals for each floor. The quantity of sodium 



