VIl] 



OF THE 



UNIVERSITY 



-CALIFORNIA 



BUTTER-MAKING^ 121 



It is impossible to obtain all the fat by creaming, 

 no matter how long the milk may be permitted to 

 stand. There are always a certain number of the 

 smaller fatty globules which never rise to the surface, 

 and which thus remain in the skim milk (Fig. 19). 



FIG. 19. MICROSCOPICAL APPEARANCE OF SKIM MILK. (Kirclmer.) 



Even by using centrifugal separators it seems im- 

 possible to separate all the fatty globules from the 

 milk. It has been calculated that the amount of fat 

 left in the skim milk by the old methods of separa- 

 tion may amount to, on an average, '8 per cent. By 

 the use of separators, on the other hand, not more 

 than, on an average, '2 per cent should be left in the 



