INDUSTRIAL FUMIGATION" AGAINST INSECTS 



21 



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. 



Figure 22. — Lobby of apartment house being fumigated with hydrocyanic acid gas 

 generated by the discoid method, showing round white wafers distributed over the paper 

 runner and the empty cans from which they have been shaken. These wafers are 

 wet when distributed, but after the evolution of the gas they become dry and 

 harmless. 



The proper number of cans of discoids should be placed on each 

 floor to be fumigated, and the distribution of the fumigant should 

 be started on the top floor, always from a predetermined point and 

 approaching the exit. One man should open the cans, using a spe- 

 cially devised can opener that makes a clean cut close to the rim 

 (fig. 23), while two or more men take the opened cans and scatter 

 the discoids over the floor or among the machinery. 



Discoids should not be placed directly on painted or varnished 

 floors or woodwork, for the liquid hydrocyanic acid is likely to injure 

 the finish. Two or three thicknesses of newspaper or wrapping paper 

 will provide adequate protection against any liquid that may ooze 

 from the discoids. 



