IQ CIRCULAR 369, U. S. DEPT. OF AGRICULTURE 



be forced up along the neck of the bag and over the edge of the 

 container. If the cyanide is properly packaged, however, there will 

 be no overflow. 



When large dosages are used in barrels, sometimes as large as 30 

 pounds, it is safer to place the cyanide in gunny sacks. When 

 charges in such sacks are lowered into the barrels, gas is evolved 

 at Once and the operator must work with dispatch. The evolution 

 of gas can be delayed by wrapping the sack in paper and tying 

 the bundle with cord strong enough so that the bundle can be lifted 

 and lowered into the barrel without danger of breakage. A person 

 can then lower several charges before gas is discharged from the 

 first. 



Placing the Genekatoks 



In the fumigation of large open mills or warehouses, all the 

 generators for one floor can be grouped in a position reasonably close 

 to the exit. It is not necessary to distribute them throughout the 

 room, for the gas is quickly dispersed to all parts of the enclosed 

 space. In fact, where it is impractical to seal off the several floors 

 of a rather small, tight building, excellent results can be obtained 

 in calm weather by placing all the generators on the lower floor. 

 The gas will quickly diffuse throughout the building. 



How to Geneeate the Gas 



After the mill or warehouse has been prepared for the fumigation 

 and the generators have been placed in their proper positions, the 

 water and acid are measured out and distributed in the generators. 

 The acid can be poured from the carboys into heavy galvanized-iron 

 buckets, which will resist the action of the acid long enough for it to 

 be distributed without accident. If crocks are used for generators, 

 the acid must be poured into the Avater slowly with a rotating mo- 

 tion, lest the heat developed by the chemical reaction between the 

 acid and water cause the crocks to break. If the crock should crack, 

 the operator must empty it immediately into some handy container 

 provided for such an eventuality. 



When the water and acid have been mixed, the sodium cyanide, 

 which has previously been weighed into the proper quantities and 

 wrapped, should be lowered carefully into the generators. If sev- 

 eral floors are to be fumigated separately, the cyanide should be 

 dropped first into the generators on the top floor, and then on the 

 next lower floor, and so on to the bottom. Starting with the one 

 farthest from the exit (previously determined), proceed from gen- 

 erator to generator calmly and without delay. Do not retrace steps 

 to a generator accidentally overlooked. If several lines of gener- 

 ators converge at one exit, an operator should be assigned to each 

 line and at a predetermined signal each should start dropping 

 the cyanide in the most distant generator in his line. 



Since the gas is generated as soon as the acid-water mixture comes 

 in contact with the sodium cyanide, the operators engaged in drop- 

 ping the cyanide should wear gas masks, except for very small jobs 

 where only one or two generators are used. 



