Chemical Analysis of Milk and Its Products. 245 



that of the empty dish-j- asbestos, gives the amount of 

 ash in the sample weighed out. 



289. 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.) 



290. About 25 grams of finely-divided cheese are ex- 

 tracted 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 meas- 

 ured into a 250 cc. saponification flask and treated ac- 

 cording to the Eeichert-Meissl method, as already ex- 

 plained under Detection of Artificial Butter (282). 4 



TESTS FOR ADULTERATION OF MILK AND CREAM. 



291. Use of the ref ractometer. The immersion re- 

 fractometer furnishes a delicate apparatus for the de 

 tection of watered milk. 2 100 cc. of milk and 2 cc. of 

 25% acetic acid are heated for twenty minutes at 70 C. 

 This is then placed on ice for ten minutes and filtered. 

 The refractometer reading of the clear filtrate is then 

 taken at 20 C. If this reading is above 40 the milk is 

 not watered, while figures below 40 show adulteration by 

 watering. 



2913. The nitric acid test may prove useful as cor- 

 roborative evidence that a sample of milk has been 



1 See Arb. Kais. Ges.-Amt., 14, 506-598. 



2 Leach, Food Analysis, 2nd ed., p. 168. See also Jr. Ind. and Eng. 

 Chem., 1911, p. 44 and p. 573. 



