14 



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



DOSAGE 



The dosage is computed on the basis of the quantity of sodium 

 cyanide required. For general mill or factory fumigation where no 

 large quantities of materials are stored, 1 pound of sodium cyanide 

 will produce enough gas to fumigate 1.000 cubic feet of space, if 

 the building is of reasonably tight construction. If the building 

 to be fumigated is filled with merchandise, the dosage required will 

 vary according to the nature of the merchandise. Dosages have been 

 computed for the fumigation of the more important commodities and 



will be discussed in 

 a later section of this 

 circular. 



The Generator 



For large -scale 

 fumigations a water- 

 tight 50-gallon 

 wooden oil barrel 

 (figs. 1, 12, and 16) 

 is the most suitable 

 generator to use. 

 Metal barrels are not 

 satisfactory. Barrels 

 in which paint, glue, 

 molasses, pitch, etc., 

 have been stored 

 should be avoided, 

 for when the acid is 

 added it may eat out 

 these materials from 

 between the staves, 

 thus causing a bar- 

 rel thought to be 

 liquid-tight to leak. 

 Barrels should be 

 cleaned and allowed 

 to stand full of 

 water overnight pre- 

 vious to the day of fumigation. Each barrel will hold a maximum 

 charge of 30 pounds of sodium cyanide, or enough to fumigate 30.000 

 cubic feet of space. T\ Tien it is necessary to fumigate small rooms of 

 a few thousand cubic feet as separate units, earthenware or stone 

 crocks (fig. 13) of appropriate size can be used. Oil barrels sawed 

 in half are used less often. 



Each barrel generator should be set in a galvanized-iron washtub 

 in which has been placed a pailful of water containing several hand- 

 fuls of washing soda. This precaution provides for catching and 

 neutralizing any of the acid-water mixture that may leak out of the 

 barrel. 



If 3 or 4 bricks are placed in the bottom of the washtubs for the 

 barrels to rest on, they will not become stuck in the tubs. It is much 

 better to have tubs large enough in diameter at the bottom so that 

 the barrels will not come in contact with the sides. 



FlGUBE 15.— A good illustration of workmen's indifference 

 to spattering sulphuric acid. Most industrial plants have 

 crews familiar w ith pouring acid; yet few are particular 

 to avoid spattering and dropping acid. 



