262 REPORT OF THE CHEMIST OF THE 
to litmus by acid, separates as a precipitate, while neutral 
calcium casein does not separate thus. At the point of neutrality 
with litmus, the body formed, that is, neutral calcium paracasein 
is precipitated. Jn this respect and in this respect only does there 
appear to be a marked difference between the properties of casein 
and paracesein compounds. This is right in harmony with what 
takes place when rennet acts on milk in the presence of soluble 
calcium salts,—-an insoluble calcium paracasein is formed. This 
shows that our preparation of paracasein had not reverted to 
casein. | 
Preparation of base-free paracasein.—In 50 ce. of lime-water, 
requiring 21.1 cc. of ba hydrochloric acid for neutralization, 
we dissolved .5 gram of our ash-free paracasein preparation. 
The solution became neutral to phenolphthalein after the addi- 
tion of 16.9 cc. of “= hydrochloric ‘acid. This leaves calcium 
oxide equivalent to 4.2 cc. of ~, hydrochloric acid as combined 
with the proteid or .01176 gram of CaO, which is 2.35 per et. 
of the paracasein, and this is the basic calcium paracasein. 
When 18 cc. of = hydrechloric acid had been added, a pre- 
cipitate began to separate, but the solution. was still alkaline to 
litmus. When 18.5 cc. of the acid had been added, precipita- 
tion was complete. This leaves calcium oxide equivalent to 
Z.6 ce. of ~ hydrochloric acid as combined with the proteid, 
or .00728 gram of CaO, which is 1.46 per ct. of the paracasein, 
and this is the neutral calcium paracasein. 
When 21.1 cc. of * hydrochloric acid had been used, an 
amount necessary to neutralize exactly the lime-water used for ~ 
dissolving the paracasein, the proteid was still precipitated. It 
was now quite easily soluble in warm 5 per ct. salt solution and 
readily so in hot 50 per ct. alcohol. On warming, the precipi- 
tate separated on the bottom of the beaker and was easily gathered 
in a mass on a stirring rod. This mass was very plastic, show- 
ing a tendency to flow when kept warm; it also possessed the 
property of being drawn into ‘long, fine, silky threads. It be- 
haved in every respect like base-free casein. 
In another experiment, we dissolved 1.5 grams of our para- 
casein preparation in lime-water and then exactly neutralized the 
solution with hydrochloric acid. The precipitated proteid 
was washed with alcohol and ether and dried at 100° ©, Deter- 
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