552 
JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 17 
4 minutes was necessary to be effective, and if there was X of an inch of 
germea, it was necessary to expose the material for 6 minutes in order to 
kill all stages of the insect. If the box contained X of an inch of germea, 
12 minutes were required to kill all stages. 
If the temperature was reduced to 176°F, an exposure of 11 minutes 
was necessary to kill the insects in X of an inch of germea, and 70 
minutes were required to produce the same effect at a temperature of 
122°F. Six minutes exposure was long enough to kill all of the insects in 
an open box with no germea. 
These experiments seemed to show quite conclusively that the usual 
sterilization processes as practiced by at least some of the mills, were 
not killing all of the insects which might be found in the prepared 
cereals, so we set about trying to find some other more satisfactory 
method of accomplishing this purpose. 
As it is always difficult to keep the steam pressure constant in any 
sterilizing apparatus, it seemed that it would be much better to use, if 
possible, a source of heat that could be made constant, and electric 
heat, of course, seemed to be the most available. After a series of 
experiments I found that a sheet of metal placed close to coils of electric 
wire could be heated to a high degree of temperature and this tempera¬ 
ture maintained without any care on the part of the operator. 
The apparatus that was finally devised for sterilizing such material 
as germea, corn meal, cream of wheat and other breakfast cereals, con¬ 
sists of three metal plates each with a heating element under it. These 
plates were placed one above the other in zigzag fashion so that the 
cereal running from the upper plate dropped on to the second plate and 
from the second on to the third plate. This provides for the material 
being turned over a time or two during its descent from the end of the 
first plate to the end of the third and prevents the material that is on the 
bottom at the beginning of the sterilizing process remaining in this 
position during the whole of the process. 
The material should be poured on the plates slowly enough so that it 
will form a thin covering over the plates as it descends. We have found 
that the material passes over the plates more rapidly and there is less 
danger of its sticking to the plates if the whole apparatus is subject to 
some vibration. 
We have found that it takes the material that is to be sterilized about 
2 seconds to run over these hot plates and as the temperature of the 
surface of the plate is 300°F. a cereal passing over these three plates 
