FEEDING CHLORINATED MILK TO THE ALBINO RAT 1 
By J. W. Read, Head of the Department of Agricidtural Chemistry , Arkansas 
Agricultural College , and Harrison Hale, Head of the Department of Chemis¬ 
try, University of Arkansas 
INTRODUCTION 
Considerable interest has been shown 
recently in the feasibility of using 
available chlorine, particularly in the 
form of hypochlorites, as a germicide 
in milk and milk products. Many 
dairymen are now using hypochlorite 
solutions sold under such trade names 
as B. K. (Bacteria Kill) to cleanse and 
disinfect their utensils, and it is also 
known that some of these have ven¬ 
tured to add these preparations to their 
milk with a view to preservation. 
Because of this practice, the question 
naturally arose as to what harmful 
effects, if any, might be produced by 
the consumption of milk w T hich had 
been treated with given amounts of 
available chlorine. 
The results reported in this paper 
cover certain experiments conducted in 
1919-20 on white rats to determine 
whether or not there would be any 
apparent ill effects on the rats by the 
consumption of liberal amounts of 
whole milk treated with definite con¬ 
centrations of active chlorine either as 
chlorine water or in the form of sodi¬ 
um and calcium hypochlorites. These 
studies constituted one phase of an 
investigation undertaken to determine 
the efficiency of available chlorine as a 
germicide in milk and milk products. 
EXPERIMENTAL PROCEDURE 
Arsenious acid. —Baker and Adam¬ 
son’s C. P. arsenious acid was still fur¬ 
ther purified by recrystallization three 
times from hot water. It was then 
sublimed three times. Carefully dried 
crystals from the third sublimation 
were used to prepare the standard 
arsenious acid solution. 
Potassium iodide. —Merck’s Rea¬ 
gent, neutral potassium iodide, was 
used in a 20 per cent aqueous solution 
for the iodometric titration of chlorine. 
Starch solution. —This solution 
was prepared as directed in Treadwell 
and Hall’s Analytical Chemistry. 2 
Two cubic centimeters of the starch 
solution were used for each titration. 
Preparation of the standard 
arsenious acid solution. —This solu¬ 
tion was prepared in accordance with 
the recommendation of Washburn, 3 
using sodium hydroxide and phos¬ 
phoric acid solutions of known strength 
to insure a better regulation of the 
hydrogen-ion concentration during the 
titrations and to obtain more sensitive 
end points. The sodium hydroxide 
was purified by alcohol, and the phos¬ 
phoric acid was Merck’s Reagent, 85 
per cent, sp. gr. 1.710. 
Iodometric titration of chlo¬ 
rine. —An accurately prepared one- 
tenth normal arsenious acid solution 
was used to titrate the iodine liberated 
from 15 c. c. of 20 per cent potassium 
iodide solution by a definite volume of 
dilute hypochlorite solution or chlorine 
water. In the case of the hypochlorite 
solutions, satisfactory end points were 
not readily obtained if the concentra¬ 
tion of the active chlorine was much 
greater than 6 to 12 mgm. per 100 c. c. 
of solution to be titrated. The plan 
followed to obtain this strength in¬ 
cluded the dilution of 12.5 c. c. of the 
stock hypochlorite solution to 500 c. c., 
whereupon 10 c. c. of the dilute solution 
(representing 0.25 c. c. of the stock 
preparation) were used for the titration. 
It was, however, not necessary to follow 
the above procedure of diluting when 
titrating the chlorine water, in which 
case 1 c. c. of the stock solution was 
diluted to 100 c. c. at the time of titra¬ 
tion. 
Experimental animals. —The diet 
of the experimental animals consisted 
of an intimate mixture of equal parts 
of finely ground whole wheat and finely 
ground yellow corn, a liberal quantity 
of treated whole milk, and 2 per 
cent of a salt mixture consisting of 
equal weights of sodium chloride and 
calcium carbonate. Four animals, two 
females and two males, were used in 
1 Received for publication July 15, 1924; issued June, 1925. Research Paper No. 9, Journal Series, L^ni- 
versity of Arkansas. 
2 Treadwell, F. P. analytical chemistry, tr. by w. p. hall. Ed. 3. 2: 652. 1911. 
2 Washburn. E. W. the theory and practice of the iodometric determination of arsenious 
acid. Jour. Amer. Chem. Soc. 30: 31-46, illus. 1908. 
Journal of Agricultural Research, Vol. XXX, No. 9. 
Washington, D. C. May 1, 1925. 
Key No. Aik. 7. 
19976—25f-7 
(889) 
