. 



Detection of Adulteration. 231 



Finally in combined adulteration we have : 



f MX ft 100 f,1 ff, M X 100 f,-| 



L 10U M -J" ~w 



100 



Other formulas according to Vogel are : 

 The addition of water in per cent 



= Y x 10 10 



The removed amount of fat in per cent 



= 100 X -^F^ 2 

 ii 



or according to Bohmlander : 

 v = X w W, in which w = the contents of water in the 



1*2 



suspected sample and W = the contents of water of the 

 unsuspected sample, and 



E = 100 1 1 



fi r 2 



(E = removed fat in % of the fat content) 



The establishment of the suspicion and the establishment of 

 the amount of adulteration are greatly supported by the examina- 

 tion of the milk serum free from proteins, which contains the sub- 

 stances dissolved in the milk, the content of which is subject to 

 only the slightest variations. The examination is carried out 



1. Through the specific gravity, or 



2. Through refractometric observations. 



It is best to prepare the serum according to Ackermann by the 

 addition of . 25 c. c. of a solution of calcium chloride of a specific 

 gravity of 1.1375, to 30 c. c. of milk, which mixture is thoroughly 

 shaken in a reagent tube. The tube is closed with a rubber stopper 

 through which a glass tube is inserted as a reflux condenser, 

 and it is then heated to boiling for 15 minutes. The tubes are 

 then rinsed in cold water and the condensation water of the cool- 

 ing tube is united with the serum by slow, repeated and careful 

 shaking. With milk which is in a state of decomposition, the milk 

 serum turns cloudy and the values of refraction are also changed. 

 Milk from affected udders which is considerably changed, fre- 

 quently curdles only following the addition of double quantities 

 of calcium chloride solution. Differences in the refraction values 

 of 2.4 to 2.50 indicate about a 10% adulteration. The removal 

 of cream does not change the refraction value of the milk. 



For refraction the serum prepared according to Ackermann 

 does not have to be filtered, but this should be done for the deter- 



