30 



CIRCULAR 369. U. S. DEPT. OF AGRICULTURE 



Figure 28. — Two outdoor fumigation vaults under one roof, built of brick, finisbed on 

 the inside with Keen's cement, and equipped with doors shutting against rubber 

 gaskets to prevent gas leakage. Note ventilators in roof to aid in ventilation when 

 lighter-than-air gas is used. (Photograph by Perez Simmons.) 



Figure 29. — Outdoor structure built for fumigation of dried fruits. It is made of 

 hollow tile, plastered on the inside with Keen's cement, and equipped with a re- 

 frigerator-type door. Note funnel-shaped openings above the door, through which 

 a liquid fumigant can be poured into evaporating trays suspended from the ceiling of 

 the vault. (Photograph by Perez Simmons.) 



If calcium cyanide is used, it can be sprinkled in a thin layer on a 

 strip of paper laid on the floor or on shelves built for the purpose. 

 Chloropicrin can be applied by pouring the dosage into the evaporat- 

 ing pan or by forcing it in through a piping system with com- 

 pressed air. The mixtures of ethylene oxide, methyl bromide, and 



