186 REPORT OF THE CHEMIST OF THE 
upon the amount of acid used in the precipitation. Danilewsky, 
in his work, used only enough hydrochloric acid to effect a good 
precipitation of milk-casein and thus he formed more or less of 
the unsaturated salt, soluble in hot 50 per ct. alcohol. Thus, it 
is easy to understand how he came to the erroneous conclusion 
that milk-casein consists of two proteids. - } 
(4) Relation to Freudenreich’s work.— It will be noticed that 
the solubility of the two salts in solution of calcium carbonate 
or calcium lactate is slight. In the case of the saturated para- 
casein salt, it was found in one experiment that only 1.2 per ct. 
of the salt was soluble in saturated solution of calcium carbon- 
ate at 122° F. (50° C.) and only 1.12 per ct. was soluble in a 
2 per ct. solution of calcium lactate at 122° F. (50° C.). The 
unsaturated paracasein salt had a solubility of 5.01 per ct. in 
calcium carbonate solution and 4.70 per ct. in the calcium 
lactate solution. 
The determination of these solubilities was made in the hope 
of finding some explanation of the results obtained by Freuden- 
reich® in his studies relating to the power of lactic-acid organ- 
isms in effecting proteolytic changes in milk-casein. Freuden- 
reich found that sterile milk, treated with powdered calcium 
carbonate and then seeded with certain lactic-acid-producing 
bacteria, showed an increase of soluble nitrogen-compounds, in 
both caseoses and amides. He determined the soluble nitrogen 
by passing the milk through a Chamberland filter. He does 
not state the amount of total nitrogen in the milk at the begin- 
ning of the experiment but only the amount of soluble nitrogen. 
Assuming that the milk used by Frendenreich contained 0.5 per 
ct. of total nitrogen, the average of milk, and recalculating his 
results in percentages of total nitrogen, we obtain the data given 
in the following table: 
13..andw. Jahr. d. Schweiz., 12: 279 (1898). 
