88 
Proceedings of Royal Society of Edinburgh. [sess. 
phosphates, chlorides, and sulphates, calcium, and, with the above 
exception, a proteid uncoagulable (lact.-alb.). 
MgSo±, or “ salted wliey” This has all these constituents, but it 
is incompetent to demonstrate sulphates in it. 
If milk be dialysed into distilled water through vegetable parch- 
ment-paper, after twelve hours the fluid outside is faintly acid and 
slightly opalescent , but it shows no chemical evidence of proteid, 
save a very faint turbidity with Tauret’s reagent. It is faintly 
acid in reaction. It has lactose and the salts (chlorides, phosphates, 
sulphates), and calcium. 
Conclusions. 
(1) Caseinogen is not, in the ordinary acceptation, in solution in 
milk-plasma, it is in the most intimate association with the fat ; in 
all probability the particles consist of fat in direct ratio and of 
caseinogen in indirect ratio to their bulk : in this sense, caseinogen 
is “particulate.” 
The arguments that caseinogen is present as an envelope are still 
entitled to respect; but there is some evidence pointing to this 
proteid being interstitially associated with the fat. 
(2) Both the clots and precipitates in milk and in “ pure 55 
caseinogen are more or less cohesive agglutinations of the pre- 
existing particles : there is no trace of fibrous structure. 
(3) The so-called “ pure solutions ” of caseinogen are suspensions 
of particles upon whose presence depends their coagulability, in 
which respect they resemble diluted milk or concentrated whey. 
Their pressure-filtrates contain no proteid. 
(4) Ringer’s view of the clotting of casein being a twofold pro- 
cess receives confirmation in my experiments : it would be con- 
venient to name the product of enzyme action upon caseinogen, 
procasein. 
(5) The free acid present in many ee essences of rennet is, in 
many cases, and especially in the absence of lime, responsible for 
the precipitation of casein : it is a precipitant of procasein, not an 
adjuvant to enzyene action. Casein differs in many respects from 
the type of “ coagulated proteid.” 
