252 REPORT OF THE CHEMIST OF THE 
The data in Tables XIV and XV are summarized as follows: 
(1) Casein takes up sulphuric acid from dilute solutions more 
quickly than it does hydrochloric acid, the maximum amount of 
acid being taken up in little more than 45 minutes (Table XV) 
when solution of proteid does not set in. 
(2) The amount of sulphuric taken up by casein, the proportions 
of acid and casein being the same, is greater than in the case of 
hydrochloric acid. 
(3) The equilibrium ratio is not even approximately a constant, 
but increases rapidly with the dilution of acid employed. This 
behavior is in accord with that usually observed in adsorption. 
Extraction of sulphuric acid taken up by casein.—The work was 
carried out in detail in the manner described on p. 240. The 
essential results, properly corrected, are given without the details 
of correction in the table following: 
TABLE XVI.— SHow1InNG AMoUNTS OF SULPHURIC ACID EXTRACTED FROM 
CASEIN BY WATER. 


Ratio of 
Duration |Cc. N-—1000/Cc. N—1000} Cc. N-—1000 | Concen- |/conce’n acid 
Noon of contract} acid in acid acid tration | in casein, 
(a ele between | acid-casein| extracted left of to 
: acid-casein before from in acid in |conc’n acid 
and water. | extraction.|acid-casein. casein. water. in water. 
0 301.4 0 301.4 €.0175) CLiz— 220) 
eee oe eee 1 min. 301.4 SP aac] 268.5 .3291 816 
2 ae as ee Oe 15 min. 301.2 35.0 266.2 . 3489 764 
Dc neh ake ee 1 hr. 301.0 Sell 263.9 3747 704 
BNP Ae eee 24 hrs. BOle2 Sond 262.5 tote 695 
PSG cueeton Fee faces Habre. 299.6 37.4 262.2 .3704 708 






As would be expected from the high value of the ratio of acid 
in casein to acid in water (Table XV), the results indicate that 
sulphuric acid is not so completely extracted from casein by water 
as is hydrochloric acid. About 80 per ct. of the acid that can be 
extracted, however, by one portion of water is extracted in one 
minute. After 5 hours of constant agitation with the same amount 
of water, only about 12 per ct. of the acid that had been taken up 
by the casein was removed, and 1 gram of casein then contained 
about 700 times as much acid as did each cc. of the surrounding 
solution. 
