132 FUMIGATION METHODS 
on the surrounding plants. Paper used for this pur- 
pose can be rolled together, laid away, and is ready for 
future use. When everything isin readiness, doors and 
ventilators should be closed, and the cyanide lowered 
into the vessels by loosening the strings. The gas is 
given off almost immediately and a small quantity will 
leak out of the house; but if the room is reasonably 
tight the greater portion of it will be kept within for 
a time sufficient to destroy the pests. When the 
proper time has elapsed, varying, of course, for different 
plants, the ventilators should be opened from the out- 
side, so that the gas can escape as rapidly as possible. 
After free circulation is obtained by opening the doors 
and ventilators, all traces of the gas will have dis- 
appeared from the house in from thirty to forty 
minutes. ‘The house can then be closed if desired. 
The residue left in the jars should be emptied, as 
previously described. 
Boxes for fumigating small plants.—Where it is 
desirable to fumigate several hundred small plants, 
small boxes, such as described in Chapter XI., can be 
used to good advantage. In most cases a special box, 
such as shown in Figs. 47 and 48, is desirable. The 
box should be as nearly air-tight as possible, with a 
removable cover or trap-door which can be quickly 
closed. A special box, shown in Fig. 71, was con- 
structed and used by Prof. E. D. Sanderson for the 
fumigation of small plants. Small wire or slatted trays 
can be used to good advantage for the fumigation of 
cuttings, such as coleus and various other plants. 
Potted plants can be fumigated in the same box if 
necessary. 
