NOVEMBER 26, 1897.] 
taken off by hand, and the corn is then 
quickly carried to the cutting machines, in 
which, by a series of knives and scrapers, 
the kernels are quickly and cleanly sepa- 
rated from the cob. Any stray bits of cob 
or silk which may be mixed with the corn 
are now taken out as it passes through the 
‘silker,’ a machine arranged somewhat on 
the plan of a gravel-sifter, that is, with two 
cylindrical wire screens one inside the other, 
placed on an incline and rotating in oppo- 
site directions. The corn drops through 
the meshes of the screens, while the refuse 
passes out at the lower (open) end. 
The corn is now weighed, mixed with 
water in the proper proportions, and is then 
ready for the ‘ cooker.’ There are several 
varieties of these machines in use, all of 
which are alike in principle but differ some- 
what in details of construction. Their ob- 
ject is to heat the corn evenly and quickly 
to a temperature of 82—-88° C. (180-190°F.) 
and to deliver it automatically into the 
eans. A single machine fills about thirty 
eans aminute. After having been wiped, 
the cans are capped, soldered and tested for 
leaks. Sterilization, the final and most im- 
portant step in the whole process, now fol- 
lows, this being done in retorts, by steam 
under pressure. The length of heating, or 
‘ processing,’ and the pressure which is given 
vary somewhat in different factories. 
As we have shown in our previous paper, 
in order to insure sterilization in practice, 
itis necessary to obtain and maintain a tem- 
perature in excess of 100° C. (212° F.) 
throughout the contents of the can. Inter- 
mittent sterilization may be employed, but 
is less efficient and is not practicable upon 
a large or commercial scale. We have 
found by experiment that sixty minutes at 
121° C. (250° F-.) is sufficient time for steril- 
izing corn, and it seems probable that this 
can be shortened somewhat or the temper- 
ature reduced. Further experiments are 
in progress to decide this question. 
SCIENCE. 
801 
Through a demand thatcanned corn shall 
be very light in color there has been, ap- 
parently, a pressure put upon the packer to 
shorten the time of heating or to reduce the 
temperaturein his retorts. The large losses 
which have resulted in recent years from 
sour corn have been due principally to this 
demand. By the use of registering ther- 
mometers we have proved that corn is a 
very poor conductor of heat, and that the 
time necessary to bring all portions of the 
center of the cans to the requisite temper- 
ature is a factor whose importance cannot 
be overestimated. We have proved by ex- . 
periment that, with 13 pounds of steam in 
the retort, the corresponding temperature 
of which is 118.8° C. (246° F.), it requires 
55 minutes for the same temperature to be 
registered at the center of a can placed in 
the middle of a retortful of corn. Withthe 
same pressure and under the same condi- 
tions at the end of 45 minutes a temper- 
ature of 114° C. (237.2° F.) was reached, 
and at the end of 30 minutes 108.3° C. 
(227° F.). Thus it is evident that with 
the present methods any reduction of time 
of heating is attended by considerable risk. 
If any means could be devised by which 
the heat would more quickly reach the cen- 
ter of the cans it might be safe to shorten 
the time of heating. There is a prospect 
that before long some such modifications 
may be possible. 
We have made a careful bacteriological 
study of all the different steps in the pro- 
cess and of the corn as it comes from the 
field, and have found upon the corn in the 
field bacteria which appear to be identical 
with those isolated from cans of sour corn. 
Repeated tests of corn from the cob showed 
the presence of bacteria. Corn which had 
passed through the cooker, and cans of corn 
which had been ‘retorted’ for 30 minutes 
or less, also contained the same species of 
bacteria as were found upon the raw corn. 
All these bacteria liquify gelatin, and 
