12 MILK 



on account of the liability of the upper layer 

 of the liquid to be richer in fat than the lower ; 

 the overflow, therefore, does not represent the 

 mixture. 



Total Solids. — This determination may often 

 be made with sufficient accuracy for practical 

 ptirposes by evaporating a measured volume 

 {e. g., 3 or 5 c.c.) in a shallow nickel dish from 5 

 to 8 cm. in diameter. Nickel crucible-covers are 

 suitable. The thin glass (Petri) dishes used for 

 microbe culture are convenient. When greater 

 accuracy is required, and especially when the 

 ash is to be determined, platinum dishes are the 

 most satisfactory, but owing to the present price 

 of this metal, quartz dishes are now much used. 

 Either the translucent or transparent quartz is 

 suitable, the former being less expensive. 



Good results may be secured as follows : A fiat 

 dish, 3.5 cm. in diameter, with sides 0.5 cm. high, 

 is provided with a thin fiat watch-glass cover 

 that fits rather closely. The total weight of the 

 cover and dish is noted. 2 or 3 c.c. of the sample 

 are run into the dish from the pipet, the watch- 

 glass placed on, and the weight taken as rapidly 

 as possible. The glass prevents appreciable 

 loss from evaporation dtuing an ordinary weigh- 

 ing. The cover is removed, the dish heated on 

 the water-bath or in the water-oven, and weighed 

 from time to time (with cover on it) until the 



