246 — REpPoRT OF THE CHEMIST OF THD ~ 
CaO. When the addition of acid is carried farther, a point is 
reached where the solution becomes neutral to litmus and much 
more milky in appearance than the solution neutral to phenol- 
phthalein. A solution of casein in lime-water was made neutral 
to litmus by the addition of ™. hydrochloric acid; to this solu- 
tion alcohol was added, throwing down a white precipitate. The 
precipitate was washed with alcohol and ether and dried at 100° 
C. This preparation contained 1.13 per ct. of CaCl,. On anal- 
ysis we found that 1.27 grams gave .0257 gram of CaO and. .0093 
gram of Cl (equivalent to .0072 gram of CaO,) leaving .0185 
gram of CaO or 1.46 per ct. as combined with the proteid. Sdldner 
recognized this combination and attributed to it a content of 
1.55 per ct. of CaO. Another preparation contained 0.86 per ct. 
of CaCl, and 1.48 per ct. of CaO combined with casein. 
Behavior of calcium casein solution toward rennet enzym and 
calcwm chloride.—A solution of basic calcium casein, the com- 
pound neutral to phenolphthalein, is not coagulated by rennet 
enzym either in the presence or absence of soluble calcium salts, 
as calcium chloride. A solution of neutral calcium casein, the 
compound neutral to litmus, is coagulated by rennet, in the 
presence of soluble calcium salts. When the soluble calcium salts 
are removed by ammonium oxalate, no coagulation occurs. These 
statements are in agreement with the observations of others. 
Casein present in milk as neutral calcium casein.—Our results 
appear to confirm in every respect the work of Séldner in regard 
to the relation of inorganic compounds to milk-casein. We have 
had the advantage of isolating the two compounds, which with 
him were more largely matters of inference. Of these two cal- 
cium casein compounds, the one containing about 1.55 per ct. of 
CaO and neutral to litmus and coagulable by rennet enzym in the 
presence of soluble calcium salts, appears to meet all the require- 
ments of milk-casein. So far as our present knowledge goes, we 
seem to be justified in regarding milk-casein as a compound of 
the base calcium oxide (1.55 per ct.) and the ash-free proteid 
casein. 
The behavior of calcium casein compounds toward. soluble 
calcium salts.—Basic. calcium casein, prepared by dissolving free 
casein in limewater and making neutral to phenolphthalein by 
acid, is coagulated by soluble calcium salts on warming to 35° to 
