364 Chittenden and Painter— Casein and its 
no sulphur reaction when boiled with 2 per cent. sodium hydroxide, 
but contains 1°13 per cent. of sulphur, while caseoalbumin is stated to 
contain 1:23 per cent. of sulphur. Hence, according to these investi- 
gators, casein is a mixture of two bodies, one of which is rich in sul- 
phur, while the other contains a somewhat smaller amount. The 
objection which these investigators make to the use of acetic acid in 
the preparation of casein, is that from a sodium acetate solution, 
casein itself is not precipitated, or only in part, but that the precipi- 
tate consists mainly of the protalbin body. Further, Danilewsky 
and Radenhausen claim that caseoalbumin dissolved in 1 per cent. 
sodium hydroxide and allowed to stand for 24 hours at the tempera- 
ture of the room, is changed almost completely into caseoprotalbin, 
with loss of sulphur and calcium phosphate. In a similar manner, 
protalbin dissolved in lime water, with addition of alcohol and phos- 
phoric acid, can be changed into caseoalbumin. 
Hammarsten,* however, takes exception to these views and points 
out that the peculiar behavior of Danilewsky’s casein towards boiling 
50 per cent. alcohol, depends in part upon its content of calcium phos- 
phate, the presence of which impurity depends upon the use of hydro- 
chloric acid in the precipitation of the casein, which acid does not 
favor the removal of the salt as well as acetic acid. Using acetic 
acid as the precipitant and then employing a casein three times so 
precipitated, and which analysis showed to be almost entirely free 
from calcium phosphate, Hammarsten, by treatment with boiling 
alcohol, was unable to. obtain anything more than a trace of sub- 
stance corresponding to caseoalbumin. Further, casein is unques- 
tionably changed by boiling with alcohol, as Hammarsten clearly 
shows; in fact it is well known that heating an albuminous body in 
water is liable to change its nature, at least its solubility, and there 
is no reason why treatment with 50 per cent. alcohol should not lead 
to a like result. Again, Hammarsten points out clearly another 
inconsistency in the reasoning of Danilewsky and Radenhausen in 
connection with the so-called conversion of caseoprotalbin into caseo- 
albumin. The former body is stated to be poorer in sulphur than 
the latter, and yet we are told that the protalbin body can be con- 
verted into caseoalbumin by simple solution in lime water and addi- 
tion of phosphoric acid, with or without alcohol. Yet how it is 
possible by this method of treatment to convert a body with a small 
* Zur Frage, ob das Casein ein einheitlicher Stoff sei. Zeitschrift fir physiologische 
chemie, Band vii, p. 227. 
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