6g 



FUMIGATION WITH HYDROCYANIC ACID GAS. 



The fumes of hydrocyanic acid gas are deadly to all 

 forms of animal life if used strong enough. Conse- 

 quently this process must be used with much care, not 

 only because it is highly poisonous but because it is 

 harmful to vegetation under certain conditions, about 

 which we know very little at present. 



It may, however, be used at great strength on 

 dormant wood, and as treatment for cleaning briars is 

 strongly to be recommended. 



One must bear in mind the fact that the fumes 

 are deadly poisonous to man, so that great care must 

 be exercised in using it. 



Proceed as follows : Any air-tight chamber of 

 known capacity may be used, and the briars should be 

 placed within it. Then proceed to fumigate with the 

 following : 



For every 300 cubic feet of space use : 



i-oz. of cyanide of potassium, 

 i-oz. of sulphuric acid. 

 4-ozs. water. 



The acid is poured into the water in an earthenware jar, 

 and then the cyanide is dropped into it and the fumes are 

 allowed to rise for an hour. 



The shed must be then well ventilated for some 

 hours before being entered. 



