262 H. §S. H. WARDLAW. 
milk as in whole milk. We must therefore ascertain how 
the contents of phosphorus and calcium differ, if at all from 
those of whole milk before we can with strict justification 
deduce from a comparison of the amounts of these con- 
stituents in spun milk and in the dialysate of whole milk 
the proportions of them which exist in a diffusible condition 
in whole milk. 
When milk is spun long enough in a centrifuge (for over 
half an hour), the fat collects in a solid layer which may 
be easily removed from the top of the liquid. The liquid 
portion is therefore diminished by a volume equal to that 
of the fat or cream. The following measurements allow 
this diminution of volume to be calculated in percentages 
of the original volume of the milk. The milk was spun in 
cylindrical, flat-bottomed tubes; the volumes of the different 
portions of the milk were therefore proportional to the 
lengths of tube occupied by them. 
Diminution of volume of the liquid part of milk due to the removal of 
the fat or cream in a centrifuge. 
Mik, | Total eight | Lena of | eae 
3 12:0.cm,. | 12°3 em: 0:7 cm. 5:4 
4 12-7 ,, 12-0 ,, 0-7 ,, BB. 
Ba teen 126 0-7 ,, 5-3 
mean +. “Sie eee 5°4 ,, 
It will thus be seen that if the fat or cream removed — 
contain no CaO or P.O; the amounts of these in a given 
volume of milk will be increased to the extent of 5°4% by 
merely spinning in a centrifuge. As, however, cream con- 
tains a certain amount of ash, a direct determination of 
the ash, CaO and P.O; in the fat or cream removed from 
100 cc. of milk was made. The following results were 
obtained. | 
