17 
As soon as all preliminaries have been arranged and the acid 
has been added to the water in the generators, a bag containing the 
eyanid should be left at the side of each generator. 
After seeing that the generators are placed in rows so as to afford 
opportunity for rapid action and the acid has been added to the 
water in each of the jars, begin operations in the upper floor of the 
building and place the cyanid gently in each jar, passing from one 
jar to another as quickly as possible and as quickly leaving the room, 
going downward to the next floor, where the process is repeated until 
the last floor or basement is reached, where exit is made. The outer 
doors should be locked and a watchman stationed outside until the 
process is completed. 
This process may be varied if strings or stout cords are used for 
lowering the bags of cyanid into the jars from the outside, as pre- 
viously deseribed. 
A still day should be selected for fumigation. In case of a high 
wind the fumes of the gas will escape strongly, which will not alone 
interfere with the success of the fumigation, but may cause alarm 
to neighbors should the building not be an isolated one. 
Better results are claimed for a warm temperature, say 70° F. 
or above, than in a temperature as low as 50° F. or below. Under 
50° most insects become torpid and the effective action of the chemical 
will be diminished, especially in very low temperatures. 
The best time that could be chosen, and which is generally used 
where circumstances permit, is during daylight on a Saturday after- 
noon or very early Sunday morning. This gives a longer exposure 
than can usually be obtained unless a day preceding a holiday, when 
all mill hands are on vacation, may be chosen. This permits of a 
full exposure, as in many cases it removes the necessity of ventilating 
the building until early the following Monday morning. 
A single fumigation will in most cases destroy all but a few indi- 
vidual insects, especially if conditions are favorable. As a rule, how- 
ever, it is only a matter of a few days or weeks before the moths may 
be seen beginning to fly about the building or resting on the walls 
and machinery. To guard against reinfestation, therefore, a second 
treatment must be given, at the end of the third to the fourth week, 
according to the number of moths which may have issued in the mean- 
time. If after the expiration of another interval the insects are still 
present a third fumigation may be necessary. A third treatment is 
not usually required, however. 
Most millers who practice this method of fumigating employ it 
once a year, some at the intervals above stated, others at intervals 
of six months. One Michigan miller claims that in his case after one 
thorough fumigation it is unnecessary to repeat the process until 
two years have elapsed. 
[Cir. 112] 
