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New YorkK AGRICULTURAL EXPERIMENT STATION. 265 
THE RELATION OF CASEIN AND ITS COMPOUNDS TO PARACASEIN AND 
ITS COMPOUNDS. 
We have made preparations of the following compounds, which 
have been described in the preceding pages: 
Casein, the base-free proteid or uncombined proteid. 
- Basic calcium casein, containing the free proteid combined with 
about 2.40 per ct. of CaO. 
Neutral calcium casein, containing the free proteid combined 
with about 1.50 per ct. of CaO. 
Casein salts of acids, formed by combination of the free pro- 
teid with acids. 
Paracasein, the base-free or uncombined proteid. 
Basic calcium paracasein, free paracasein combined with about 
2.40 per ct. of CaO. | 
Neutral calcium paarcasein, free paracasein combined _ with 
about 1.50 per ct. of CaO. 
Paracasein salts of acids, formed by combination of the free 
proteid with acids. 
A comparison of the properties of casein and paracasein and 
their compounds strongly suggests that they are chemically alike, 
paracasein and its combinations being larger molecular aggrega- 
tions than casein and its corresponding combinations, in accord- 
ance with the suggestion of Loevenhart. The following state- 
ments serve to bring out the close resemblance more strikingly. 
(1) The free proteids, casein and paracasein, possess the same 
solubilities in warm 5 per ct. salt solution and hot 50 per ct. 
alcohol. They possess the same peculiar plastic properties when 
warmed and show the same power of being drawn out in fine, 
silky threads. 
(2) Casein and paracasein form compounds containing the 
same amounts of combined calcium oxide. 
(3) Casein and paracasein, when treated with dilute acid in 
the proportion of one gram to about .5 cc. of a hydrochloric 
acid, are changed into bodies having the same properties, which 
differ strikingly from the properties of the free proteids. 
(4) Neither basic calcium casein nor basic calcium paracasein 
is coagulated by rennet, either in the presence or absence of 
soluble calcium salts, Basic calcium casein and basic calcium 
