16 CIRCULAR 3 6 9, U. S. DEPARTMENT OF AGRICULTURE 



as in 4-gallon crocks, it is best to use two paper sacks, one of which 

 will fit easily inside the other. By wrapping the unoccupied por- 

 tion of the sacks tightly about the cyanide and tying with a string, 

 a compact package is obtained, which can easily be lowered into the 

 acid-water mixture with one hand. If two paper bags are used and 

 the cyanide is placed in the inside bag, the action of the chemicals 

 is delayed and the operator is less likely to encounter gas when 

 lowering several charges into the acid containers; however, the 

 danger is still present and operators should wear gas masks and 

 oiled gloves. If the sacks are merely tied close above the cyanide, or 

 twisted, without wrapping, during the reaction the acid-water mixture 

 may 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 and should wear 

 a mask and oiled gloves. 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 Generators 



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 Generate 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 water slowly with a rotating mo- 

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

 acid and water cause the crocks to break. Crocks should be placed 

 in small metal tubs, containing some water and washing soda, before 

 the acid is poured into the water, so that the acid will not be spilled 

 if the crock should crack. 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- 



