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POMONA COLLEGE JOURNAL OF ENTOMOLOGY 



easy to see that a very small saving of materials in some one operation, or 

 perhaps a little adding of expense in another, would in the long run, amount 

 to a difference of thousands of dollars to those who are now compelled for 

 their own safety to have the fumigating done. Out of the many problems and 

 urgent questions with which this subject is replete, the present article will con- 

 sider briefly the use of water in fumigation. 



In the production of hydrocyanic acid gas by the action of acid upon 

 cyanide, it is absolutely necessary to add a certain definite proportion of water 

 in order that the action shall be complete and the maximum amount of gas 

 obtained for the chemicals used. Mr. R. S. Woglum, the Department of 

 Agriculture expert who has been carrying out fumigation investigations at 

 Whittier for several years, has long since called attention to the fact that to 

 vary the amount of water from a certain optimum standard, is to change very 

 materially the ultimate results obtained. His original conclusions were based 



Figure 53. "Frosted" Generators 



upon laboratory work with the chemicals. As a result of his investigations 

 he recommends as giving the best all around results the following formula : 

 Water three parts, sulphuric acid one part, and potassium cyanide one part. 

 This having been determined, it was an interesting matter to follow 

 up our local fumigators and examine the actual practice in this regard. 

 Three out of four of the outfits studied were found to be using this standard 

 formula. Those using it were getting very satisfactory results from it. All 

 the cyanide "burned" and no "baking" or "frosting" took place in the generat- 

 ing dishes. When the refuse was turned out of the dishes there was no hard 

 residue left, showing conclusively that the action had been complete. 



In the case of one outfit using a different formula a very dift'erent result 

 was encountered. Here the generating dishes were in a very dirty condition, 

 (Figure 53), nuich of the dose having "frosted," so that each time it was 

 dumped out, a very liberal supply of the light colored flaky substance 



