SPRAYING AND FUMIGATING. 



541 



One of the most accurate fumigation tables is given 

 by Mr. W. J. Allen, of New South Wales. The following 

 table has been selected from this : 



After the tent is in place over the tree, a few shovel- 

 fuls of earth should be thrown on the lower rim of the tent, 

 resting on the ground to make it completely gas-tight. 



The tent is then ready for charging. The best gener- 

 ator is an earthenware vessel. This is placed outside, close 

 to the tent. The requisite amount of water is placed in the 

 vessel and the acid is added. Into this the cyanide of 

 potassium, previously weighed out in a small sack, is 

 dropped. The generator is then held at arms-length and 

 placed beneath the tent, which is then snugly closed and 

 left for 40 or 45 minutes. Both the cyanide of potassium 

 and the gas are extremely poisonous and must be handled 

 with great care. 



Usually the fumigation is done at night. If carried 

 on during the day the tent should be painted black. 



The most complete work on the subject of fumigation 

 is one entitled Fumigation Methods, by Prof. W. G. John- 

 son. 



