412 



CREAM. 



we have not a definite space through which the globules of fat 

 must pass, as in the cream separator, where the layer of milk is 

 always of constant thickness ; the space is determined by the 

 depth of the layer of milk set. 



It was pointed out by Golding, and the fact has been amply 

 confirmed by the author, and later by Bolton and Eevis, that 

 the milk below the cream layer is of practically uniform com- 

 position, except at the extreme lower portion, as is shown by 

 the following table. The milk contained 3-45 per cent, fat, 

 and the depth was 24 inches ; samples representing a layer of 

 about J inch were taken at various times and depths : 



TABLE CXLIV. RISTNG OF CREAM IN MILK. 



Bolton and Revis have taken advantage of this fact to prepare 

 a milk of any specified percentage of fat for infant feeding. 



Thus, if milk of known fat content be allowed to stand, and 

 the percentage of fat in the lower portion estimated, then the 

 percentage of milk to be removed in the upper layer to give a 

 milk of any specified percentage of fat is 



100/ - 100/i 

 /.-/i 



where / = per cent, fat in original milk, 

 /! = per cent, fat in lower portions, 

 / 2 = per cent, fat desired in upper portion. 



The formula 



mav be transformed into 



k 



t ~2, where k is a constant. 

 ri 



