INSECT CONTROL IN FLOUR MILLS. 21 



Estimating Spaces. 



After a decision to fumigate has been made, the amount of space 

 to be fumigated must be determined by securing the inside measure- 

 ments of the length, width, and height of each room. No deductions 

 should be made for machinery, bins, etc. 



Amount of Chemicals Needed. 



Once the cubic contents have been determined the amount of chemi- 

 cals needed can be calculated easily. In the treatment of single tight 

 rooms 1 ounce of cyanid is recommended for each 100 cubic feet of 

 space. Where a reasonably tight mill has 4 or 5 floors the follow- 

 ing standard, suggested by Dean, should be followed, as the gas 

 is light and has a tendency to concentrate on the upper floors. Use 

 1 pound of sodium cyanid to each 1,000 cubic feet of space in the base- 

 ment, to each 1,200 cubic feet of space on the first floor, to each 

 1,300 cubic feet of space on the second floor, to each 1,500 cubic feet 

 of space on the third floor, and to each 1,600 cubic feet of space on the 

 fourth and fifth floors. When buildings are rather loosely con- 

 structed, a larger amount of cyanid will be needed, but no directions 

 can be given that will be as useful in determining the amount neces- 

 sary to offset the looseness of individual mills as one or two experi- 

 mental fumigations. 



According to the 1-1^-2 formula recommended on page 18, for each 

 100 pounds (1,600 ounces) by weight of cyanid required there will be 

 needed also 2,400 fluid ounces of sulphuric acid. 



Number of Generators Required. 



If 4-gallon crocks are used for generating the gas, one crock will 

 be needed for each 4 pounds of cyanid required, or for each 6,400 

 cubic feet of space, when 1 ounce of cyanid is used to each 100 cubic 

 feet of space. Where larger generators are used, as discussed on 

 page 18, determine the amount of cyanid to be used in each container 

 and use it to divide the total cyanid required for the building or room 

 to secure the number of generators needed. It is always well not to 

 overtax the capacity of a generator. 



Placing of Generators. 



In placing the generators or jars, care must be taken to have them 

 sufficiently distant from machinery, belting, sacks, walls, etc., so that 

 there may be no danger of injury from spattering during gas genera- 

 tion. The reader is directed to examine carefully figures 8 to 11 

 for illustrations of how best to arrange generators. In using crocks 

 it is always best to place beneath each crock some old sacking or 

 papers, as not infrequently there is a slight spattering of the floor 



