18 



SOME FUNGOUS DISEASES OF ECONOMIC IMPORTANCE. 



structecl fumigating box which would be air-tight and provided with 

 some means to allow of the ready removal of material from the 

 chamber at different times during the process of fumigation, and at 

 the same time to prevent the escape of an appreciable amount of the 

 formaldehyde gas. ' To insure an absolutely air-tight compartment 

 the box was constructed of an inner and outer casing with layers of 

 building paper between the two. A large glass door swung on heavy 

 hinges was fitted to the front of the box. The sectional view shows 

 the construction of the door, which is similar to those of large 

 refrigerators (see fig. 1). Double glass was provided and the edge 

 of the door and the face of the casing were beveled, thus making 



larger bearing sur- 

 faces, which were 

 covered with felt 

 cloth. The salient 

 feature of the box 

 is the arrangement 

 of the drawers for 

 the removal of the 

 fumigated material 

 (see fig. 2). These 

 were built in the 

 side of the box and 

 were supported in 

 a large frame, the 

 arrangement being 

 such that when 

 the drawers were 

 closed and fas- 

 tened, by means of 

 the catches at the 

 sides, the gas was 

 prevented from es- 

 caping. When it 

 was desired to remove the material in any particular drawer, that 

 drawer was pulled out and the cultures removed, the back of the 

 drawer coming in contact with the surface of the supporting frame 

 closing the opening. The sides of the drawers were perforated and 

 the bottom made up of cross strips. This arrangement permitted a 

 free circulation of the gas through the drawers. The quantity of gas 

 escaping when the drawers were pulled out during an experiment 

 was negligible. An opening was arranged in the rear of the box 

 and connected by a suitable casing to a laboratory hood, by means 

 of which the gaseous contents of the box were exhausted after an 

 experiment. This fumigating box had an air space of 50 cubic feet. 



171 



Fig. 1. — Sketch showing the front elevation of the fumigating 

 box used in the experiments and the construction of the door. 



