Relative Amount Skimmed Milk and Cream 183 



slighter degree. Small -sized fat globules, viscosity of 

 the milk, and coagulation of part of the casein by 

 incipient fermentations, all tend to make separation 

 more difficult; but in a majority of cases, unless the 

 milk is so sour as to be coagulated, it may be completely 

 creamed with a centrifugal separator, but will require 

 a slower feeding (a reduction of 10 to 15 per cent will 

 usually suffice), and a higher speed of the bowl, or both. 

 Conditions affecting the relative amount of skimmed 

 milk and cream. The relative amount of skimmed 

 milk and cream is affected by the rate of inflow, 

 by the speed of the bowl, by various special con- 

 trivances upon the machines themselves, and to a 

 slight extent by the temperature of the milk. In 

 the ordinary machine the size of the skimmed milk 

 outlet is fixed, and therefore at a given velocity the 

 outlet will discharge a nearly uniform quantity of 

 fluid. If then, the milk is turned into the bowl at 

 such a rate that .8 of it escapes through the skimmed 

 milk outlet, we shall have .8 skimmed milk and 

 .2 cream. If now we reduce the rate of inflow 

 by .1, we shall get just as much skimmed milk as 

 before, but only one -half as much cream; or if the 

 inflow is increased by .1, we shall get the same 

 amount of skimmed milk and once and a half as 

 much cream. If under the first conditions all of the 

 fat was gathered into the cream, we shall have just 

 as complete a separation as before, but shall simply 

 get a cream containing a greater or less percentage 

 of fat, provided that the increase of inflow has not 

 increased the total amount above the capacity of the 



