INDUSTRIAL FUMIGATION AGAINST INSECTS 



13 



FORMULA 



For best results the chemicals should be mixed according to the 

 following formula : 



Sodium cyanide pound— 1 



Sulphuric acid pints l 1 /. 



Water a do 3 



PROPER ORDER OF PLACING CHEMICALS IN GENERATOR 



To generate hydrocyanic acid gas by this method, the operator 

 should first pour the water into the generator and then add the acid. 

 If the procedure is reversed, the reaction is so violent that the oper- 



Figure 14. — Workmen weighing- sodium cyanide for large warehouse fumigation. Man 

 at right shoveling cyanide in 1-ounce lumps from 100-pound case into gunny sack 

 held by man in center. Man at left with charge weighed about to enter warehouse 

 and place sack beside generator. 



ator may be dangerously burned by the spattering of the acid-water 

 mixture. The sodium cyanide is not added to the mixture of water 

 and acid until everything is in readiness for the fumigation, as it 

 causes an immediate chemical reaction in which h} T drocyanic acid 

 gas is given off (fig. 16). The pure gas is colorless, but when mixed 

 with steam produced by the chemical reaction it has the appearance 

 of a light bluish smoke. It has an odor resembling that of peach 

 kernels. 



2 Chemical tests indicate that a 1-1^-2 formula yields more gas than the l-l%-3 

 formula here recommended. The smaller quantity of water often results in a crystalliza- 

 tion of the residue which makes the emptying of the containers after fumigation more 

 difficult. In general large-scale work the authors have found the 1—1%— 3 formula more 

 practical and the results satisfactory. 



