106 Report oF THE CHEMIST OF THE 
In studying the data embodied in Table XI, we notice the 
same fact to which attention has already been called, viz.: that, 
in the absence of free acid, the monolactate undergoes pepsin di- 
gestion more rapidly than the dilactate. When, however, free acid 
is present, the reverse is true, the dilactate digesting more rapidly 
than the monolactate. The initial activity of digestion is consid- 
erably greater in both cases in the presence of acid. The follow- 
ing explanation is suggested to show why, in the presence of free 
acid, the dilactate digests more rapidly. The monolactate is first 
converted into dilactate and thus uses some of the acid, so that 
less acid is left free to take part in the pepsin digestion. 
(4) Comparison of digestibility of casein dilactate and casein 
dihydrochloride with and without acid.—The casein dilactate and 
dihydrochloride were prepared by treating milk with 0.6 per cent. 
of lactic acid and 0.2 per cent. of hydrochloric acid. The resulting 
products were washed and prepared for digestion as described in 
(1) and (8) preceding, except that the materials were not ground 
with sand and were not heated. In 1 and 2 no free acid was added 
to the digestion bottles, while in 3 and 4 we used 0.4 per ct. of 
hydrochloric acid. 
TaBLE XII.—SuHowi1Nne DIGESTION oFf- CASEIN DIHYDROCHLORIDE 
WitTH AND WitHouT AcIb. 
| PprceNnTAGE or NrrROGEN IN MaTERIAL, 
EXPRESSED IN FoRM OF WATER- 
re Total | Soxnuspie Nirrocen. 
MATERIAL acid | Ritrogen | 
} used in ne aah | 
aes ottle. 
digestion. In 4 | fIn’8 | In 24 | In 48 | In 72 
hours. | hours. | hours. | hours. | hours. 
eae Pore | Mg TTY USS | BESS | Ear | Pao‘ 
. Casein dilactate........ 8) i , 7.95 4.2 . 
3 Sear diny deg nonde:: , . Been ce beeen eolee oops oes 
. Casein dilactate........ 3 Ei | 84.9¢ <O . 58 $ 
4. Casein dihydrochloride. . 0.4 0.730 | 83.56 | 85.90 | 92.20 | 94.94 97.27 
The data in Table XII show no essential difference in digesti- 
bility between the casein dilactate and casein dihydrochloride. 
This is true both in the absence and presence of free acid. 
Increased digestion is caused by free acid. The most marked 
increase being in the first period (4 hours) of digestion. 
(5) Comparison of digestibility of cottage cheese made from 
whole milk and from skim-milk.—We desired to test the influence 
