Chemical Analysis of Milk and its Products. 223 



for fifteen hours. The ether is then distilled off, the 

 flasks dried in a water oven at 100 C. to constant weight, 

 cooled and weighed. The method is apt to give too low 

 results and, therefore, not to be preferred to the Babcock 

 test for cheese (102). 



277. c. Casein (total nitrogen X 6. 25). About 2 grams 

 of cheese are weighed out on a watch glass and trans- 

 ferred to a Jena nitrogen flask, and the nitrogen in the 

 sample determined according to the Kjeldahl method 

 (253); the percentage of nitrogen multiplied by 6.25 

 gives the total nitrogenous components of the cheese. 



278. d. Ash. The residue from the water determina- 

 tion is taken for the ash; it is preferably set fire to, in 

 the same manner as explained under determination of 

 ash in butter (267), before it is placed in the muffle oven 

 and incinerated. The increase in the weight above that 

 of the empty dish -(-asbestos, gives the amount of ash in 

 the sample weighed out. 



279. e. Other constituents. The sum of the percent- 

 ages of water, fat, casein and ash, subtracted from 100, 

 will give the per cent, of other constituents, organic 

 acids, milk sugar, etc., in the cheese. 



DETECTION OF OLEOMARGARINE CHEESE ("FILLED" 

 CHEESE). 



280. About 25 grams of finely-divided cheese are 

 extracted with ether in a Caldwell extractor or a paper 

 extraction cartridge; the ether is distilled off, and the 

 fat dried in the water oven until there is no further loss 

 in weight. 5. 75 cc. of the clear fat are then measured 

 into a 250 cc. saponification flask and treated according 



