1 68 FUMIGATION METHODS 



far as combustion is concerned. The gas is non-ex- 

 plosive when used at or below 0.25 gramme potassium 

 cyanide per cubic foot of space enclosed, other condi- 

 tions being normal. We have asked Dr. H. W. 

 Wiley, Chief of the Bureau of Chemistry, United 

 States Department of Agriculture, for his opinion re- 

 garding this matter, and quote the following letter 

 from him : 



"Cyanogen gas, or hydrocyanic acid gas, mixed 

 with air or oxygen, forms an explosive mixture, but I 

 should not think that in the proportions you mention, 

 viz., 0.25 gramme of potassium cyanide for each cubic 

 foot of air space, it would produce an atmosphere 

 which would be explosive. Hydrocyanic acid, how- 

 ever, is combustible and could be mixed with air, I 

 presume, so as to form an explosive mixture. I have 

 looked over the authorities, but can find no mention 

 of explosive properties. 



' ' The danger of hydrocyanic acid, in my opinion, is 

 not from its explosive properties, but from its highly poi- 

 sonous nature. Small quantities of hydrocyanic acid 

 gas inhaled are extremely poisonous, and are apt to 

 produce fatal results. // would be equivalent to instant 

 death for any one to enter a building filled with it. 



' ' While I do not think there would be danger of 

 an explosion in the proportions you mention (0.25 

 gramme), I would advise great circumspection in the 

 introduction of a light, unless it be an incandescent 

 electric light, enclosed in an air-tight globe. Such 

 lights should always be used where there is any danger 

 of explosion. ' ' 



Practical application. The following testimonials 



