New York AcricutturaL Experiment SratioN. 32¢ 
Effect of temperature upon solution of proteid, and of solution 
upon titration results— The set of experiments described below 
shows clearly the effect of temperature upon the rate of solution 
and also the effect of solution upon the accuracy of the titration 
method as used by Van Slyke and Hart, Laxa, Leo and others. 
The experiments were performed in the manner already described 
(p. 210). Flasks containing casein and hydrochloric acid were kept 
at 0°, 25° and 45° C. in constant-temperature baths; they were 
shaken at intervals. The titrations were made in duplicate, agree- 
ment being within o.1 cc. of N-100 alkali in all cases. The expres- 
sion, “acid fixed by casein,” used below in Table IV indicates acid 
taken from the state of solution as free hydrochloric acid, whether 
the union with casein be physical or chemical or both in part, as 
is probably the case when partial solution of casein occurs. We 
used 100 cc. of N-125 HCl for 1 gram of casein. The concentration 
of the acid used was 7.905 instead of 8, because the factor of the 
stock solution was a little less than unity. The weights of casein 
represent water-free casein, correction being made for the amount 
of moisture present, which was generally 3 to 4 per ct., this plan 
being adopted in all our work. 
In the table below, the results are arranged to show,— 
(1) Effect of temperature on the rate of solution of casein in 
acid (columns Io and IT). 
(2) Effect of solution on accuracy of titration results (compare 
columns 6 and 9 with reference to 10 and I1). 
(3) Effect of solution on amount of hydrochloric acid fixed by 
casein (compare 5 hour figures for 0°, 25°, and 45°, column 6, 
with reference to Io and II). 
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