DIFFUSIBLE PHOSPHORUS OF COW’S MILK. 265 
Percentage of P.O; of milk in a diffusible condition. 
PO, im 100 ce... of Percentage in 
Milk. Spun milk. ~ Dialysate. dialysate. 
A B 24-hour. | 48-hour. | 24-hour. | 48-hour. 
55 | 0-235 | 0-232 | 0-153 | 35-0 
59 0-216 0-212 4\5.0:076 0-136 35°5 
60 0°233 0:235 | 0:106 0-131 45:3 Yee 
61 0-259 0-250 | 0:138 0:139 54-1 54°5 
62 0-263 O-261 | O-112 0-110 42°] 42-0 
63 0:220 0°:225 | 0:123 0°122 55°3 54°8 
64 0:22] 0:21 0-106 Sy 48°6 
These results show that the amount of diffusible P2O; of 
cow’s milk waries from 35 to 557%. 
The amount of the soluble or diffusible calcium and phos- 
phorus in milk is thus by no means consistent, but varies 
between rather wide limits. This variation is striking 
when the comparative constancy of the freezing point, 
and therefore of the total amount of dissolved matter is 
remembered. Jackson and Rothera (1914) have examined 
this peculiarity and have shown that there is a reciprocal 
relation between the salts in solution in milk and the 
amount of milk sugar. 
Summary. 
1. When a large volume of milk is dialysed against a 
small volume of water, the freezing point of the dialysate 
after twenty-four hours approximates to that of the milk, 
and does not change as the dialysis is continued; a definite 
state of equilibrium is therefore reached. 
2. Milk freed from fat in a centrifuge contains 3/ more 
ash-forming substances than whole milk. 
3. The diffusible calcium of cow’s milk amounts to 30— 
40% of the total present. 
4, The diffusible phosphorus of cow’s milk amounts to 35 
—55% of the total present. 
