60 REPORT ON THE FIG MOTH IN SMYRNA. 
and there is less tendency for the fruit to acidify, as occasionally 
occurs when it has been boiled. The color, too, is if anything less 
affected by dry heat ; though this is difficult to determine positively, 
as experiments were made with a different lot of figs from those 
boiled, and under different conditions. The disadvantage of the 
dry-heat process as compared with hot water is the much greater 
exposure required, since time is an important item in the figuring. 
It is also more difficult to maintain a uniform temperature. Another 
respect in which the dry process is inferior is that it does not remove 
filth and destroy microbes on the outside of the fig, as does boiling. 
At a large khan in Smyrna has been installed an oven, heated by 
gas, for experimental work in the destruction of fig-moth larvae in 
figs. The dimensions of the oven are 2 by 2 meters by 3 meters long. 
Both ends open out, and are furnished with double doors that swing 
vertically. Passing through the oven is a track of two rails 1J meters 
apart, on which run two iron loading frames on wheels. The capacity 
of each frame is about 4 to 5^ tons, depending on whether the figs are 
loaded in sacks or in the woven baskets piled one above the other. 
The object of having two frames is that one may be reloaded while 
the other is within the closed oven and the figs are being sterilized. 
The oven is made of sheet iron 4 mm. thick. The doors are covered 
outside with sheet asbestos, with an air-space If inches in depth be- 
tween it and the sheet iron. The sides and top are covered with 
white planking three-fourths of an inch thick set out from the sheet 
iron, with intervening air spaces of depths of 6J and 4J inches respec- 
tively at sides and top. The object of the air spaces is to prevent 
burning of the wood and radiation and loss of heat. Paper put into 
these air spaces, with asbestos next the iron, would still further con- 
serve the heat. The oven is heated by gas, which is furnished by a 
large series of burners on a sliding frame that passes under the oven. 
Two thermometers are inserted in one of the doors, by which the 
interior heat may be determined and regulated. The entire cost of 
the oven was about £400, and the cost of the gas is about £3 for each 
10 hours of use. 
Considerable loss of heat accompanies each opening of the doors 
and insertion or extraction of the loaded frames. To ascertain the 
extent of this loss and the relative length of time required for the 
heat to again rise to a point sufficient to kill larvae, a loaded frame was 
inserted in the oven and a tabulated record made of the temperatures, 
taken at intervals of every quarter or half minute during its exposure 
of 10 minutes and an additional period after its extraction. 
The following figures give the temperatures of the interior of 
the oven before and during the introduction of the figs, and the 
