Nov. 24, 1923 
Active Chlorin as a Germicide for Milk 
377 
It will be noticed that the milk used in the tests was of very poor 
quality, as shown by the large number of organisms in the untreated 
milk and by the amount of gas produced in lactose broth. In both 
tests the results show germicidal action in proportion to the active 
chlorin present. Even in the 1150000 dilution there was a marked 
decrease in the number of bacteria. 
The next test, the results of which are given in Table IV, was practi¬ 
cally a duplicate of the test shown in Table II, except that the milk was 
of much better quality and different dilutions of chlorin were used. 
Table IV .—Action of sodium hypochlorite (“ BK”)—alkaline 
Active chlorin. 
Time acting 
before plating. 
Bacteria. 
Gas in lactose 
broth. 
Flavor of 
chlorin. 
Untreated. 
i hour. 
63, 5 °° 
13, IOO 
44, IOO 
50, 000 
37 , 5 oo 
37, 800 
40, 950 
50, 500 
None. 
1:1000.. 
... do. 
... do. 
Yes. 
1 1 5000. 
. . .do. 
...do. 
Trace. 
1:10000. 
...do. 
...do. 
Do. 
1!2 5000. 
...do. 
...do. 
None. 
1 m . 50000. 
...do. 
... do. 
Do. 
I!IOOOOO. 
...do. 
... do. 
Do. 
1:2 c;oooo. 
. ..do. 
. ..do. 
Do. 
These results, and others to be given, show that a germicidal effect is 
produced even in extreme dilutions, but that it is not always definitely 
proportional to the amount of active chlorin present. This variation is 
probably due to differences in composition and in quality in the milk 
used. 
Investigation of the best form or source of the active chlorin was then 
undertaken. 
Authors of the ortho-tolidin test claim that one part of active chlorin 
in 200,000,000 parts of water can be detected by this method. This 
was verified, while the starch-iodid showed a sensitiveness of one part 
in nearly 10,000,000 parts of water. When applied to milk the ortho- 
tolidin test was found valueless, as no color appeared except with very 
high concentrations. When starch-iodid is used in milk containing 
active chlorin a sensitiveness of one part in 160,000 was the best that 
could be obtained, much lower than that necessary for a satisfactory 
reagent. Moreover, the color faded rapidly when only small amounts 
of chlorin were present. 
A study was made of the rate of disappearance of active chlorin from 
chlorin water, sodium hypochlorite, and calcium hypochlorite. To 
determine the rapidity at which the active chlorin disappeared, the 
following tests were made at room temperature, using starch-iodid as 
indicator, the time stated showing the difference between the time of 
the addition of the active chlorin and the time a negative test was shown. 
This disappearance of the active chlorin’ is probably due to the forma¬ 
tion by the chlorin of compounds with the organic matter in the milk, 
and the chlorin in the chlorin water, being more readily available, acts 
more rapidly. 
