62 FUMIGATION 



liquid may be poured directly on the grain. The bin or warehouse 

 is to be first made as tight as possible; heavy sackcloth may be 

 placed on top of grain in the bin. If the bin is very deep, a gas 

 pipe with the lower end plugged, and with holes drilled in the side 

 to allow escape of liquid, may be thrust down into the grain. This 

 aids in distributing the insecticide at different levels. Two pounds 

 of liquid for every one hundred bushels of grain, or two pounds for 

 every one thousand cubic feet of space are advised. The process 

 should last over night. The building or bin should be well aired 

 afterward. Workmen should be cautioned against using lighted 

 cigars or pipes, or lights of any kind, during their work with this 

 agent or while ventilation is in progress. 



Hydrocyanic Acid Gas. -This is made by uniting cyanide of 

 potash or cyanide of soda with sulfuric acid (H 2 SC>4) . Unlike the 

 preceding, this gas is lighter than air. It is not inflammable nor 

 explosive at the strengths used by entomologists, but is most 

 deadly in its effects upon man or animal if inhaled. In the hands 

 of an expert, it is a safe agent, for knowledge of its dangerous 

 qualities results in intelligent precautions in its use. The odor of 

 the gas is much like that of peach pits, and the slightest trace of 

 such an odor constitutes a warning. 



As an insecticide it is far superior to bisulfid of carbon, in that 

 it is fatal to all stages of most insects, including the egg stage. 

 Only the chemically pure cyanide should be used (98 per cent), 

 and sulfuric acid of a specific gravity of 1.83 or over. Cyanide of 

 sodium may be used in place of cyanide of potash if the latter 

 cannot be obtained, but should be fresh, and it calls for one-half 

 more acid than does potassium cyanide. For example, the standard 

 formula for every one hundred cubic feet is one ounce cyanide of 

 potash, one fluid ounce of commercial sulfuric acid, and three 

 fluid ounces of water ; if cyanide of soda is used the formula would 

 be: Cyanide of sodium, one ounce; sulfuric acid, one and one-half 

 fluid ounces; water, four fluid ounces. For the fumigation of 

 orchard trees with hydrocyanic acid gas, see Chapter XI. 



Fumigating Scions and Other Nursery Stock. Many states 

 require that nursery stock sold therein or brought within the state 

 boundaries be fumigated. Nurserymen, therefore, should know 

 how to conform to these requirements. In fumigating nursery 

 stock, an air-tight box or room should be constructed, cubical 

 contents of which can be easily figured. For every one hundred 

 cubic feet of space use one ounce cyanide of potassium, two ounces 



