24 ANALYTICAL PROCESSES. 



out, and received in a weighed flask. Two j more por- 

 tions of ether, 10 c. c. each, are shaken with the acid 

 liquid, blown out and added to the first. The ether is 

 then distilled off, and the fat dried and weighed as 

 above. 



Lactocrite Method. In response to the demand 

 for a method for fat determination, capable of affording 

 fairly accurate results in the hands of dairymen and 

 others unskilled in analytical operations, many process- 

 es have been devised, among which, those depending 

 upon the use of centrifugal machines have proved 

 most satisfactory. The lactocrite of De Laval is of this 

 class. The following description of the machine and its 

 use is given by H. Faber (Analyst, XII, p. 6,) "The appa- 

 ratus itself consists of a strong round steel disc on a spin- 

 dle, and test boxes of platinum-plated brass, with grad- 

 uated glass tubes. 10 c. c. of the sample of milk to 

 be tested are run into a small test glass, afterwards 10 

 c. c. of glacial acetic acid, containing 5 per cent, by vol- 

 ume of concentrated sulfuric acid, are run into the 

 same glass, which is closed with a perforated cork- 

 stopper, in which is inserted apiece of glass tube; this 

 serves to prevent a concentration of the contents of the 

 test glass during the boiling. In a water bath, arrang- 

 ed to hold twelve test glasses, these are heated by 

 steam or gas for seven or eight minutes, after which 

 time the casein has been completely dissolved, while 

 the liquid has acquired a slight violet tinge. The next 

 step is to charge the test boxes. These consist of a 



