ACTIVE CHLORIN AS A GERMICIDE FOR MIRK AND 
MILK PRODUCTS 1 
By Harrison Hale, Head , Department of Chemistry , University of Arkansas , and 
William L. BLEECKER, Bacteriologist , Arkansas Agricultural Experiment Station 
The use of chlorin in some form as a germicide in water purification 
is well established, and continued experience has demonstrated its 
efficiency and proven that it is not harmful. 3 Exceedingly delicate 
tests for an excess of free chlorin have been devised, perhaps the most 
satisfactory being that of Ellms and Hauser, 3 using o.or per cent solu¬ 
tion of ortho-tolidin in io per cent hydrochloric acid. Even when 
those tests fail to show the presence of free chlorin in water the germi¬ 
cidal action continues, as shown by bacterial counts. The chlorin 
apparently forms complex compounds with the organic matter in the 
water, which, while not giving the test for free chlorin, still continues 
to possess germicidal properties. 3 
The object of this investigation has been to determine whether a 
similar use of active chlorin as a germicide for milk and milk products 
is possible and, if so, in what form it is best applied. 
Preliminary tests made in March, 1918, on ice cream, by placing small 
amounts of sodium hypochlorite in the mixture of pasteurized cream 
before freezing, gave these results: 
Table I. —Preliminary tests 
Sample. 
Available chlorin. 
Bacteria 
per cc. 
B. Colt Com¬ 
munis —No. of 
positive tests 
in 5 samples, 
1 cc. each. 
Acidity after 
standing 72 
hours. 
Control. 
None. 
15,000 
One. 
I. OOO 
Sample 1. 
1:16000 “BK” 
12 , OOO 
None. 
. 909 
Sample 2. 
1:8000 
3,000 
None. 
• 727 
In making the bacteriological tests regularly the following methods 
were used: 
The milk was weighed in sterile flasks, so that each flask contained 
exactly 100 gm. The chlorin in solution was then added to each flask 
in sufficient quantity to make the desired solution, the amount of active 
chlorin in each cc. having been previously determined by titration. 
In every case the milk in one flask was left untreated as a control. After 
the chlorin solution had been added the flasks of milk were allowed to 
stand at room temperature for the desired length of time with frequent 
agitation. 
1 Accepted for publication May 2, 1923. Research Paper No. 1, Journal Series, University of Arkansas. 
2 Race, Joseph. Chlorination of water, viii, 158 p., illus. New York and London. 1918. Bib¬ 
liographies at ends of chapters. 
1 Ellms, J. W., and Hauser, S. J. Ortho-tolidine as a reagent for the colorimetric estima¬ 
tion of small quantities of free chlorine. In Jour. Indus, and Engin. Chem., v. 5, p. 915-917, 1030. 
1 913 . 
-The effect of ferric salts and nitrites on the ortho-tolidine and starch-iodide 
tests for free chlorine. In Jour. Indus, and Engin. Chem., v. 6, p. 553-554. 1914. 
Race, Joseph. Op. cit. p. 82. 
Journal of Agricultural Research, 
Washington, D. C. 
ahs 
( 375 ) 
Vol. XXVI, No. 8- 
Nov. 24, 1923 
Key No. Ark.-s 
