250: REPORT OF THE CHEMIST OF THE 
was no longer present as calcium hydroxide, that is, .0112 gram 
of calcium oxide. This amount had combined with the .5 gram 
of proteid, forming 2.24 per ct. of the calcium proteid compound, 
and this proportion indicates the basic calcium casein. 
When we had added 16.4 cc. of 2, hydrochloric acid, the solu- 
tion was just blue to litmus. This imaifaitex that calcium oxide, 
equivalent to 2.8 ce. of 2, hydrochloric acid, or .00784 gram of 
calcium oxide, was no eae present as calcium hydroxide. ~ 
This amount had combined with the .5 gram of proteid, forming 
1.57 per ct. of the calcium proteid combination, and this propor- 
tion indicates the neutral calcium casein. 
When we had added 16.6 ce. of 7, hydrochloric acid to the 
lime-water solution of casein, litmus was turned red, but no pre- 
cipitation occurred yet. After 18.5 cc of 2, hydrochloric acid 
had been added, a precipitate began to ee and the precipita- 
tion of the dissolved casein was complete when we had added 
19.2 cc. of 2, hydrochloric acid, or just enough to combine with 
all the calcium originally present in the solution used. This 
work was repeated with closely agreeing results. This precipitate 
is therefore base-free casem. A preparation made in this manner 
and thoroughly washed showed that all the calcium present was 
there as calcium chloride, either occluded in the precipitate or 
possibly in a loose form of combination with the proteid,—in any 
case there was no calcium base in combination with the casein. 
The precipitate contained in one gram, .00348 gram of Ca and 
.0064 gram of Cl, which amounts agree well for the presence of 
calcium chloride. This body, prepared by neutralizing a solu- 
tion of calcium casein, is insoluble in water but readily soluble 
in warm dilute sodium chloride solution and in hot 50 per ct. 
alcohol. 
In another experiment, 25 cc. of lime-water required 10.6 ce. 
of {, hydrochloric acid to neutralize it. We dissolved in this 
amount. of lime-water .5 gram of ash-free casein, prepared 
according to Hammarsten. To «alae this amount of casein 
completely required 10.6 cc. of 2, hydrochloric acid. The pre- 
cipitated substance was soluble in warm dilute salt solution and 
in hot dilute alcohol. To this substance we added .5 cc. of 2, 
hydrochloric acid and obtained a substance insoluble in warm 
dilute salt solution and only slightly soluble in hot dilute alcohol. 
