954 H. S. H. WARDLAW. 
between the corresponding figures given by different 
authors. Further, it has been objected that the passage of 
milk through porcelain may not simply effect a mechanical 
separation of the suspended from the dissolved matter of 
milk, but changes may be induced which bring about the 
precipitation of substances originally in solution (see 
Raudnitz, 1902). 
With regard to the method of separating the suspended 
matter from milk by spinning in a centrifuge, still less is 
known. Indeed, although it has been observed that a 
separation of some of the suspended matter of milk can be 
effected in this way, and one or two analyses of separator 
slime have been made (Fleischmann, 1901; Alson, 1908; 
Barthel, 1910), the only systematic attempt to determine 
the nature of the deposit obtained appears to be that of 
the present author (1914, 2). The investigations in this 
direction, however, have so far not thrown much light on 
the state of combination of the substances in solution and 
in suspension in milk beyond showing that calcium phos- 
phate does not exist in suspension in milk as is generally 
believed, or rather that it is not deposited when milk is 
spun in a centrifuge. More complete information will be 
obtainable in this way only when a more perfect separation 
of the suspended matter has been brought about. 
With regard to the separation of the suspended from the 
dissolved matter by means of dialysis, again very few data 
are available. When a body such as milk, in which there 
must exist a complex series of equilibria between dissolved 
and suspended substances, is allowed to dialyse against 
water, the effect is that of diluting the soluble constituents, 
which will dialyse out into the water. This dilution will 
disturb the equilibrium between dissolved and suspended 
matter, and may result in substances, originally in sus- 
pension, going into solution, just as a precipitate of an 
