84 
Proceedings of Royal Society of Edinburgh. [sess. 
the potassium salts do not antagonise this first stage of clotting ; 
in several cases it was applied, one of which is given below. 
Milk and K-cyanide + A.R. = 0 : boiled and divided in three 
portions, to one of which was added 1 m. acetic acid, result a clot ; 
to a second, 4 m. of CaCl 2 (10 % sol.), result a clot at once (showing 
that soluble casein was pre-formed) ; to a third, 1 m. acetic acid 
-I- 3 m. CaCl 2 , result clot. 
I made a large number of similar experiments with K-salts and 
caseinogen (Ringer’s pure solution), but my results are too perplex- 
ing to be published at this time ; the general result seems to point 
to a corroboration of the antagonism as alleged. Although some 
of the clots in the milk dosed with K-salts were jelly-like, others 
(ana amongst them some of those in alkaline tubes) contracted to 
clots of very high tenacity. 
Y. The Case of Decalcified Milk. 
There still remains the case of milk treated with potassium 
oxalate, which, if warmed with a not excessively acid rennet, will 
yield no clot. In order to deal with absolutely limeless substances, 
I added potassium oxalate to the rennet, and by centrifugalising a 
portion of it, obtained decalcified rennet. In like manner I centri- 
fugalised the decalcified milk, obtaining a copious deposit of amor- 
phous calcic oxalate, which passes through ordinary filter-paper. 
If a portion of the decalcified milk, which has been warmed with 
decalcified rennet for upwards of half an hour and has not clotted, 
be boiled and cooled, we find that a clot immediately appears on 
the addition of either a few m. of CaCl 2 (or other soluble salt of 
Ca, or a salt of Ba or Sr) or 1 m. acetic acid. 
Throughout these processes we have (1) the native K-salts of 
the milk ; (2) the K-phosphate, presumably formed in the double 
decomposition between the calcic phosphate and K-oxalate ; and 
(3) some excess, doubtless, of uncombined K-oxalate. The failure 
of casein to appear as a clot with rennet in decalcified milk is 
therefore due not to the presence of K-salts but to the absence of 
calcium salts. 
Decalcified milk allows its caseinogen to be precipitated by 
acetic acid and by all the proteid precipitants, as one might expect. 
