Fumigation 



the market by various firms for fumigation purposes 

 at the present day. Greenflies, white flies, and scale 

 insects in greenhouses are best dealt with by this 

 means. 



Fumigation with hydrocyanic acid is even more 

 effective, but its use in careless hands or in green- 

 houses attached to dwelling-houses is fraught with 

 danger to human life. All cracks should be closed 

 for any form of fumigation, and the air of the house 

 and the foliage of the plants should be dry. The 

 process should be carried out after dark, and the 

 house should be ventilated well before it is entered. 

 This is absolutely essential where hydrocyanic-acid 

 gas is used, for the fumes in even small quantities 

 are, deadly to human life. The materials wanted for 

 the process are potassium cyanide, sulphuric acid, 

 water and a saucer. The sulphuric acid is diluted 

 and placed in the saucer. The potassium cyanide is 

 dropped into the acid after the door of the house has 

 been securely fastened, and the ventilators are 

 opened for at least two hours before any one is 

 permitted to enter the house. -The quantities 

 required are, for every 1000 cubic feet in a green- 

 house, 1 oz. potassium cyanide, 1^ oz. sulphuric acid, 

 and 3 oz. water. 



Soil fumigation has recently received more 

 attention than hitherto, and many soil fumigants 

 are on the market. Their frequent effect is to drive 

 soil insects to seek " fresh woods and pastures new." 



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