14 MILK 



with hydrofluoric acid). The filter is added to 

 the residue, the whole ashed, the filtrate then 

 added, and the liquid evaporated carefully to 

 dryness. The ash of normal milk is about 0.7% 

 and faintly alkaline. A marked degree of alka- 

 linity and effervescence with hydrochloric acid 

 will suggest the addition of a carbonate. 



The method of the A. O. A. C. is as follows : In 

 a weighed dish put 20 c.c. of milk from a weighing 

 bottle; add 6 c.c. of nitric acid, evaporate to 

 dryness, and btirn at a low red heat tiU the ash 

 is free from carbon. 



Fat.— Many methods for fat determination 

 have been devised. The following will suffice for 

 all practical work: 



Adams' Method. — This consists essentially in 

 spreading the milk over absorbent paper, drying, 

 and extracting the fat in an extraction apparatus ; 

 the nulk is distributed in an extremely thin layer, 

 and by a selective action of the paper the larger 

 portion of the fat is left on the surface. A 

 paper, manufactured especially for this purpose 

 by Schleicher & Schuell, is obtainable in strips 

 of suitable size. Each of these yields to ether 

 only from o.ooi to 0.002 gram of extract. 



Coils made of thick filter-paper, cut into 

 strips 6 by 62 cm., are thoroughly extracted 

 with ether and alcohol, or the weight of the ex- 

 tract corrected by a constant obtained for the 



