Chemical Analysis of Milk and its Products. 215 



261. Condensed milk. The same methods are, in gen- 

 eral, followed in the analysis of condensed milk as with 

 whole milk. Condensed milk is preferably diluted with 

 three times its weight of water prior to the analysis, both 

 because such a solution can be more easily handled 

 than the undiluted thick condensed milk, and the errors 

 of analysis are thereby reduced, and because the fat is 

 not readily extracted except when the milk has been 

 diluted. The same constituents are determined as in 

 case of whole milk, viz., solids, fat, casein and albumen, 

 ash, milk sugar, and cane sugar (if any has been added 

 to the milk). The milk sugar is determined by differ- 

 ence; if the student has a knowledge of the manipula- 

 tion of the polariscope and has had experience in gravi- 

 metric sugar analysis, the milk sugar is determined 

 gravimetrically, and the cane sugar by the difference 

 between the polariscope reading after inversion and the 

 milk sugar present. 



The specific gravity of condensed milk may be determined 

 by a method similar to that of McGill. 1 50 gr. of the 

 thoroughly mixed sample are weighed into a tared beaker 

 and washed with warm water into a 250 cc. flask, cooled 

 to 60, filled to the mark and carefully mixed. The 

 specific gravity of this solution (a) is then taken and the 

 original density is calculated by means of the following 

 formula: 



Sp. gr. of condensed milk= ^\^ 



Concentration. The extent of concentration of con- 

 densed milk may be determined approximately by the 

 formula devised by McGill (loc. cit.): 



i Bulletin 54, Laboratory, Inland Rev. Dept., Ottawa, Canada. 



