New YorK AGRICULTURAL EXPERIMENT STATION. 181 
formed by the combination of lactic acid with paracasein and 
is insoluble in dilute salt solution. 
(2) Salts formed by combination of paracasein with other 
acids.— Paracasein forms salts also with other acids. Mr. A. J. 
Patten, has determined for us the amounts of acetic, hydro- 
chloric, and sulphuric acids required to form the unsaturated and 
saturated salts. In each case, acid was added to 25 grams of 
fresh curd, previously ground with sand, suspended in water, 
and finally extracted at 122° F. (55° C.) with a 5 per ct. solution 
of sodium chloride. 
TaBLeE V.— ForMATION OF COMPOUNDS BY PARACASEIN AND 
DIFFERENT ACIDS. 





Acetic acid. | Hydrochloric acid. Sulphuric acid. 
Grams of acid used.......... 0.5}. 1.0) 0.15] 0.25] 0.50) 0.15; 0.25] 0.50 
Percentage of total nitrogen 
found in form of salt-soluble 

COTTE ESE OE Pp an gee 70.0) . 5.3/27.3 |53.0 | 5.7 }19.5 141.5 | 2.4 


In this table the same general results are seen as in the 
case of lactic acid. A certain amount of acid forms with a 
given amount of paracasein a maximum quantity of salt-soluble 
product, and increase of acid beyond this quantity forms a 
compound not soluble in dilute salt-solution. 
It also appears from the results given in Table V that min- 
eral acids are required in smaller amounts than organic acids 
to saturate paracasein completely. 
SALTS FORMED BY COMBINATION OF CASEIN WITH ACIDS. 
(1) Formation of unsaturated casein salt.—We can show that 
casein readily forms an unsaturated and a saturated salt with 
an acid. In preparing the unsaturated salt, we used 5 cc. of 
freshly drawn milk, diluted it with 50 ce. of water, warmed 
the solution to 104° F. (40° C.), and then added 7, hydro- 
chloric acid until the resulting precipitate settled with a clear 
supernatant liquid, which required 2.7 ce. To this mixture we 
