46 BULLETIN 737, U. S. DEPARTMENT OF AGRICULTURE. 
rial was effectively sterilized when exposed for 24 hours in a part 
of the building where a temperature of 187° F. was reached, and 
all stages of the beetle were killed. 
The tests made show that under certain conditions steam may be 
used to advantage in sterilizing empty warehouses, as much higher 
temperatures could easily be obtained than were reached in the ex- 
periments. Dry heat, secured by fitting the building or storage 
room with sufficient radiating surface, would, of course, be the most 
practical means of heating, as steam turned directly into a room 
for some time might cause injury to the building by expansion of 
beams from moisture and heat combined. 
Other experiments have shown that temperatures of from 130° to 
150° F. result in the death of all stages of the tobacco beetle, and it 
is probable that very little if any damage to most grades of tobacco 
would follow. In cleaning storage rooms, etc., live steam or hot 
water applied through a flexible pipe fitted with a nozzle can often 
be used to advantage in destroying the insects in refuse or dust 
in crevices in the floor or walls. | 
The expense of steaming in the foregoing experiment for 24 hours 
amounted to $15.20, as follows: 
Engineer, 2 days @ $4 per day________ SID OE ES END 
Wireman, -2: days ‘(@od) pers day 22-4 a eee 2.00 
BTU Bas Ae ae © eA epee Bryn Zf ee a 4.50 
VR GET Ses See a ae Nae ee ee Pie hae eee es ts 8 . 70 
The expense of fumigating the same space (108,000 cubic feet) 
with hydrocyanic-acid gas would have amounted to about $75, or 
with carbon disulphid $60, these estimates being based on prices of 
chemicals used for fumigation at the time of the experiment. 
USE OF STEAM AS A MEANS OF STERILIZING INFESTED TOBACCO. 
Although steam furnishes, under some circumstances, an effective 
and convenient method of sterilizing storerooms or warehouses there 
are numerous difficulties which prevent its use in sterilizing infested 
tobacco. Leaf tobacco becomes more brittle if exposed to steam at 
high temperatures for any length of time, the texture and aroma 
are changed, and the color becomes darker. In spite of the general 
objection against steaming, however, there seems to be considerable 
evidence that mild steaming may be used to advantage in treating 
certain classes of cigar tobacco. In the application of steam the 
principal requisite is that the tobacco does not become too wet, and 
that unnecessarily high temperatures are avoided. 
A method of treating cigar tobacco in revolving steam drums 
has been tested in the Philippines (77). Steam was applied for 20 
minutes at a pressure of about 4 atmospheres, the temperature rang- 
