384 Chittenden and Painter— Casein and its 
was found to be quite different in its nature from protoalbumose or 
protoglobulose. The two latter undoubtedly combine with acetic 
acid, when precipitated from a salt-saturated fluid; the eompound, 
however, is readily and completely soluble in water. With proto- 
caseose on the other hand, acetic acid produces a precipitate, not 
only insoluble in the salt-saturated fluid, but also more or less insolu- 
ble in water containing a little acid. It is easily soluble in dilute 
alkali and alkali carbonate, and is not precipitated by neutralization 
with hydrochloric or acetic acid. Addition of acid, however, beyond 
neutralization immediately causes precipitation of the caseose. 
Protocaseose once precipitated with salt and which on the second 
precipitation, failed to separate from the salt-saturated fluid, was 
precipitated by a little acetic acid, washed somewhat with water, 
dissolved in very dilute sodium carbonate solution, neutralized and 
then dialyzed. in running water for nearly a week. The solution 
was then perfectly neutral to test papers and was likewise perfectly 
clear. It was evaporated to a syrup and the caseose precipitated 
by alcohol. After being washed with alcohol and ether, it was 
dried at 105° C. in vacuo until of constant weight, and then analyzed 
with the following results: 
Protocaseose A 3. 
I. 0°3703 gram substance gave 0:2160 gram H.O =6°:48 per cent. H and 
0°6500 gram CO, =47°86 per cent. C. 
II. 0°4200 gram gave 50°9 c. c. N at 21:2° C. and 765:0™™ pressure = 14°21 
per cent. N. 
Ili. 0°7053 gram fused with KOH and KNO; gave 0:0418 gram BaSO, 
= 0°81 per cent. S. 
IV. 0:4076 gram gave 0:0386 gram ash = 9°47 per cent. 
The ash-free substance therefore contained 
52°594 C. 717% H: 15°70% N. 0:90% 8S. 
Like all of the caseose bodies, this contained a large percentage of 
ash in spite of its long continued dialysis. The ash was mainly cal- 
cium phosphate with some oxide of iron, obtained in part doubtless 
from the salt used in precipitation. It is not difficult to see how 
protocaseose, precipitated by salt alone, should take up and retain 
semi-mechanically considerable inorganic matter, But in the pres- 
ent case, where the great mass of the albuminous substance has been 
precipitated by the salt added, it seems somewhat surprising that 
the caseose should separate from the clear fluid in the presence of 
