New York AGRICULTURAL EXPERIMENT STATION. 259 
substance. Eugling'® concluded from work done by him that 
acids or rennet, when added to milk, render the insoluble cal- 
cium salts soluble and more readily available for the coagulation 
of the proteid. De Vries and Boekhout*® believe that free acid 
exerts upon the coagulation of paracasein a direct influence in 
some way on its own account, independent of the formation of 
soluble calcium salts. Loevenhart®® has stated that there is no 
chemical difference between casein and paracasein, and that 
observed differences in properties are due to physical changes, 
casein and paracasein being physical modifications of one and 
the same body. According to his belief, paracasein exists in 
larger molecular aggregations than does casein. 
We thus see that, while there is a wide range of opinion in 
regard to the relation of casein and paracasein, there is a pre- 
vailing tendency to regard these proteids, milk-casein and para- 
casein, aS being essentially alike in composition. 
We have already referred to the circumstances which led us to 
regard as a mono-lactate of paracasein a body which we were 
able to separate from cheese by means of a warm 5 per ct. salt 
solution. We have indicated how we came to regard the sub- 
stance formed from this body by treatment with lactic acid as 
paracasein dilactate. We have in the preceding pages shown 
how we now regard the corresponding casein compounds. It is 
now our purpose to consider in a similar manner paracasein and 
some of its compounds, and we shall present our discussion in 
the following order: 
1. The relation of inorganic compounds to paracasein. 
2. The relation of the salt-soluble compound of paracasein to 
paracasein. : 
3. The relation between the two series of compounds pre- 
viously called paracasein mono-salts and paracasein di-salts. 
4. The relation of casein and its compounds to paracasein and 
its compounds. 
THE RELATIONS OF INORGANIC COMPOUNDS TO PARACASEIN. 
In order to study paracasein in its relations to calcium and to 
acids, it was essential to obtain a paracasein that should be prac- 
8 Landwirth. Versuchs-Sta., 31:392 (1885). 
% Landwirth. Versuchs-Sta., 55:221 (1901). 
» Zeit. Physiol. Chem., 41:177 (1904). 
