88 INSECTS AFFECTING STORED PRODUCTS. 
No insects appeared to be affected until the sixth lot was examined, 
and only a small percentage, if any, was killed. About 35 per cent 
were killed with 15 pounds to the 1,000 cubic feet, and 75 per cent 
with the highest strength used. The temperature ranged from below 
32° F. to 68° F. outside the building, which was a shed with sheet- 
iron sides, and the temperature of the rice was about 48° F, 
This follows closely the results of experiments by Hinds and 
Turner ¢ with Calandra during cold weather. 
KLuperiment No. 11.—A three-day exposure was planned to treat 
between 200 and 300 sacks of infested screenings containing princi- 
pally this species, with a quantity of rough rice and brewers’ rice piled 
in loose stacks, and in more compact stacks as in the regular storage 
room. With the same formula and 15 pounds to 1,000 cubic feet the 
room was left closed from 5.30 p. m. October 29 until 11 a. m. 
November 2, or a period of about 90 hours, although about 2 hours 
additional were required to allow the room to free itself of the gas. 
When the door was opened after this long exposure the rush of 
fumes was very strong and the sacks gave up gas for at least 24 
hours afterwards. A long search through all the sacks failed to 
discover any living Rhizopertha; and after giving a sack from the 
interior an airing, together with material from different places, a 
half-dozen adult Z7rzbolium navale Fab. were seen in motion. All 
other insects were evidently dead, though of course the entire lot 
could not be examined in detail. 
This seems to give good evidence that with a long exposure the in- 
sects can be killed in a tight room. If the room had been closed for an- 
other day doubtless the Tribolium adults would not have recovered. 
HYDROCYANIC-ACID GAS FROM SODIUM CYANID. 
Haperiment No. 12.—In the first fumigation with cyanid of soda, 
the 1-2-3 formula (1 pound cyanid,2 pints sulphuric acid, and 3 pints 
water) was used for an exposure of 24 hours at the rate of 15 ounces to 
1,000 cubic feet to test the penetrative powers of an increased dosage. 
After airing the room sufficiently samples were taken from all 
parts of the room and from all parts of the piles and exposed to the 
open air in the bright sunshine for an hour, and examined carefully. 
The piles of bags were covered with dead insects of all species, and 
especially with Lhizopertha dominica. There were many dead 
within the sacks, but probably 50 per cent of this species were alive 
at 4 inches depth in the rice and screenings, while in the lower sacks 
and those with sacks surrounding them very few were dead except 
on the outside. 
Experiment No. 13.—Another exposure of 48 hours with the same 
formula and dosage was given to over 200 bags of materials similar 
“See Hinds and Turner, Journ, Econ. Ent., vol. 3, pp. 47-56, 1910. 
