NATURE OF DEPOSIT OBTAINED FROM MILK. eB 
cally excluded, and the deposition must be due entirely to” 
the action of centrifugal force on suspended matter in the 
milk. Indeed, I have observed that, if the spinning be 
continued long enough, part of the milk may be almost 
freed from suspended matter, and a zone of clear greenish- 
yellow milk plasma makes its appearance below the layer 
of fat on the surface. See also Lachs and Friedenthal 
(1911). 
Filtration of milk through porcelain also separates the 
suspended matter from it, the porcelain allowing through 
only a clear filtrate. A doubt exists, however, as to 
whether a purely physical separation is affected in this 
way (Raudnitz, 1903). Porcelain has been shown by 
Hermann (1881) to possess the power of precipitating 
caseinogen from milk, and almost as clear a filtrate is 
obtained by stirring milk with powdered porcelain and then 
filtering as by forcing it through the pores of a Chamber- 
land filter-candle. 
In spinning milk in the centrifuge, on the other hand we 
have a purely physical means of separating some of the 
suspended matter from it,a means which will only separate 
substances which already exist in suspension in the milk. 
Very few data with regard to the character and mode of 
deposition of the substance obtained from milk in this way 
appear to be available, although a study of this substance 
is likely to give some definite information as to the physical 
state and chemical composition of the compounds existing . 
in suspension in milk. Alson (1908) isolated what he con- 
sidered to be a new protein from this deposit. 
The present communication is an account of the pre- 
liminary examination of the deposit obtained from milk by 
spinning itinacentrifuge. The following points have been 
dealt with :— 
