22 



CIRCULAR 369. U. S. DEPT. OF AGRICULTURE 



Applying the Discoids 



When large quantities of discoids are used, especially in hot 

 weather, it is advisable to chill the cans before fumigating. This 

 will greatly retard the generation of the gas and thus increase the 

 safety of operation. If solid carbon dioxide is available, a liberal 

 quantity thrown over the tops of the cans in each opened case a few 

 hours before fumigating will chill the discoids. Solid carbon dioxide 



can usually be purchased 



for from 3 to 5 cents per 

 pound. Placing cans of 

 discoids in cold storage 

 will have the same effect. 

 The proper number of 

 cans of discoids should be 

 placed on each floor to be 

 fumigated, and the distri- 

 bution of the fumigant 

 should be started on the 

 top floor, always from a 

 predetermined point and 

 approaching the exit. The 

 cans are opened with a 

 specially devised can 

 opener that makes a clean 

 cut close to the rim (fig. 

 23). If several operators 

 are engaged in the work, 

 one can open the cans 

 while the others scatter 

 the discoids over the floor 

 or among the machinery. 

 The men should take turns 

 opening the cans, so that 

 one man will not be ex- 

 posed too long to the 

 heavy concentrations near 

 the newly opened cans. 



Discoids should not be 

 placed directly on painted 

 or varnished floors or 

 Avoodwork, for the liquid 

 hydrocyanic acid is likely 

 to injure the finish. Two or three thicknesses of newspaper or wrap- 

 ping paper will provide adequate protection against any liquid that 

 may ooze from the discoids. 



When discoids are used, the fumigators are exposed to the gas 

 while they are opening the cans and distributing the contents. Good 

 gas masks are necessary and will prevent them from breathing poi- 

 sonous fumes, but there is also some danger from the direct absorp- 

 tion of hydrocyanic acid gas through the skin. 





:; 



Figure 23. — Man, protected by gas mask, removing 

 the top from a tin can containing discoids impreg- 

 nated with liquid hydrocyanic acid. 



Williams 2 has esti- 



Williams, C. L. flmigants. Pub. Health Repts. [U. S.] 46: 1018. 1931. 



