TYPHOID FEVEK IN DISTEICT OF COLUMBIA. 
Ill 
these substances kno^vn to take place during freezing; the process of 
freezing, like any process of crystallization, being one of purification. 
On the other hand, in these same specimens of ice the free ammonia 
is high. This may be accounted for by the fact that there is alwaj^s 
some leakage of this gas about ice factories using the ammonia proc- 
ess, and, as is well known, ammonia sometimes occurs in manufac- 
tured ice in such quantities as to impart a distinctly alkaline taste. 
The albuminoid ammonia and nitrites show but little if any change. 
It is further interesting to note that, while the chemical analysis of 
the water used in the plate ice system indicates an improvement in 
its quality as compared with tap water, the bacterial examination 
shows the contrary. 
The six specimens of plate ice, for example, contained the following 
comparatively high bacterial contaminations, whereas tap water 
from which it is made averaged only 64 organisms per cubic centimeter 
during the same period of time; 
No. 
of 
sam- 
ple. 
Manufacturer. 
Organisms 
per cubic 
centimeter. 
Colon bacillus. 
24 
Crystal Plate Co 
455 
Absent. 
29 
do 
5,000 
In 1 cc. 
26 
Geo’-getown Ice Co 
230 
In 10 cc. 
27 
do 
AhsPTit- 
32 
Chapin-Sacks 
470 
Do. 
34 
Purity Ice Co 
8 
In 1 cc. 
This discrepancy between the bacteriological and chemical findings 
doubtless signifies that the water in the tanks is contaminated by 
the unclean methods already noted in the inspection of the factories, 
and that, while the organisms are not entirely destroyed at the low 
temperature of the ice tank, they can not effect those changes in 
water which they bring about at ordinary temperatures and which 
result in the production of characteristic substances whose presence 
can be recognized and determined by chemical methods. 
Specimen No. 29 is a striking example of this condition. This ice 
contains 5,000 bacteria per cubic centimeter with the colon bacillus 
present in at least each cubic centimeter. On the other hand, the 
chemical analysis of this specimen does not indicate injurious pollu- 
tion. It would seem reasonable to conclude, therefore, that the bac- 
terial contamination had probably dropped into the water from the 
soiled shoes of the men working on the ice or from other sources just 
before freezing. 
The fact that all sorts of foreign particles, such as “trash,’’ fibrous 
and granular debris, straw, etc., were found imbedded in and on the 
