272 



SUCCESSFUL FARMING 



gas produced is very poisonous, as are also the cyanide of potassium and 

 sulphuric acid. When fumigating it is well to place a notice on the room 

 or house warning people not to enter. After the fumigating is accomplished 

 it is advisable to open up doors and windows and air out for ten minutes 

 or more before entering. 



The dose to be used depends upon the space to be fumigated and upon 

 the character of the plants to be treated. Dormant trees can be exposed for 



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Fumigating with Hydrocyanic Gas. 1 

 Sheet tent ready for introduction of chemicals. 



a time to very strong fumes. Growing plants must be treated cautiously 

 with very mild doses. Some of them are very sensitive to the gas and will 

 be slightly burned with any dose calculated to be of value in destroying 

 insects. The condition of the air as to moisture may influence the results, 

 since dampness favors injury from the gas. 



For nursery stock it is customary to employ for each 100 cubic feet 

 enclosed, the following: 



Cyanide of potassium 1 ounce 



Sulphuric acid 1 .25 fluid ounces 



Water 3 fluid ounces 



'Courtesy of U, 8. Dept. of Agriculture. 



