152 



VOLUMETRIC AND INDIRECT ESTIMATION OF FAT. 



It has been proposed to modify this method by raising the 

 cream by centrifugal force, and apparatus have been made to fit 

 on to the spindle of cream separators ; though more concordant 

 results are thus obtained, these methods have not the accuracy 

 of many of the volumetric methods, by which they have been 

 superseded as practical methods. 



Faber has, however, shown that very accurate results may be 

 obtained by measuring the volume of cream thrown up from 

 skim milk, after whirling in the lactocrite for one hour, and 

 dividing by 3. 



Den si me trie Method Of Pat Estimation. By placing 

 about 200 c.c. on a pleated filter and collecting such portions as 

 run through in the first quarter of an hour, the milk serum i.e., a 

 solution of the solids not fat in water may be separated without 

 much change in composition. A series of experiments by the 

 author showed that the solids not fat in the filtered milk were, 

 after correcting for the volume of the fat removed, on the average 

 0-12 per cent, lower than in the unfiltered milk. 



Vieth gives the following experiment : 200 c.c. of milk were 

 filtered ; after one hour 50 c.c. of milk had run through ; after 

 four and a half hours more, 26 c.c. were collected ; and 108 c.c. 

 were poured out from the filter. 



The results of analyses of these four milks were 



TABLE XXVII. 



This experiment shows that a portion of the proteins is removed 

 with the fat, and corroborates the author's conclusion that when 

 the portion run through in the first fifteen minutes is taken, 

 there is only a slight loss of solids not fat. 



