12 FUMIGATION OF APPLES FOR SAN JOSE SCALE. 



(fig. 1, box C), against which it was tightly pressed by the six 

 clamps to each box (fig. 1, box E; fig. 2, A, la). 



To permit quick removal of gas at close of period of exposure, 

 each box was supplied on lower rear side and at top with a 2-inch 

 pipe opening and a tight valve, the lower series (fig. 1, 8a) con- 

 necting with the common outlet pipe (8), extending to the outside 

 of the building and opening above the level of the roof, the upper 

 series (5a) joined to a pipe (5), connected with the electric blower 

 (6), for generating the air blast. This arrangement permitted the 

 simultaneous clearing out of the gas in all of the boxes, or one or 

 more boxes could be operated independently of the others. About 

 fifteen minutes were required to clear the boxes of gas, though this 

 was of course greatly diluted with fresh air almost immediately 

 after the blower was put in operation. 



To insure a uniform distribution of gas in the boxes from the 

 start, a small generating box was constructed and placed on the 

 floor at about the center, as shown in detail in figure 2, A, B, 3 a-d. 

 This box, except as noted, was fairly tight, with a door in front 

 for introducing the chemicals and four square hollow arms with the 

 ends open and seven J-inch holes along each side. A shaft of heavy 

 steel wire extended from side to side in the upper part of the box, 

 projecting on one side in the form of a crank. A small metal cup 

 was rigidly attached to the middle of the wire shaft to receive the 

 potassium cyanid (fig. 2, A, 3b). Beneath the cyanid cup was space 

 for the introduction of a small jar containing the necessary sulphuric 

 acid and water (3c). A string was attached to the crank end of 

 the shaft bearing the cyanid cup, by means of which the cup could 

 be inverted and the cyanid thus dropped into the jar beneath. With 

 the door of the generating box closed, the gas was mostly forced 

 out through the four arms, insuring a fairly uniform distribution 

 from the moment the chemicals were brought together. 



A heavy slat platform (fig. 2, A, 2) was provided somewhat 

 above the generating box, and on this were placed all packages of 

 fruit to be treated, as barrels, baskets, boxes, etc. The apparatus 

 as described proved well suited for the work in hand, and it is 

 believed was as tight as it was practicable to make it. At no time 

 during fumigation could the odor of escaping gas be detected at 

 cracks or around the door, though the gas was forced out into the 

 room to some extent when the air blast was turned on. 



In the operation of fumigation the two valves of a box were 

 first closed, the package of fruit to be fumigated placed on the slat 

 platform, the weighed cyanid lightly wrapped in tissue paper, put 

 into the cyanid cup, and just before closing the fumigating box the 

 jar of measured acid and water was inserted into the generating box 



