32 MILK 



For amino-derivatives and ammonium com- 

 pounds, so c.c. of the milk are mixed in a flask 

 marked at 250 c.c. with i gram of sodium chlorid. 

 A 12 % solution of tannin is added, drop by drop, 

 tmtil no further precipitation occurs. The mix- 

 ture is diluted to the mark, shaken and filtered 

 through a dry filter. For amino-derivatives, 50 

 c.c. of the filtrate are treated for nitrogen in the 

 usual way. For ammonium compounds, 100 c.c. 

 of the filtrate are mixed with magnesium oxid 

 and about 50 c.c. distilled, the distillate being 

 received in a known volume of standard acid. 

 Large excess of magnesium oxid must be avoided. 



Lactose. — For this determination, A. O. A. C. 

 employs Soxhlet's method with the following 

 reagents : 



Copper sulfate solution. — 34.639 grams of pure 

 crystallized copper sulfate are dissolved in water 

 and made up to 500 c.c. 



Alkaline tartrate solution. — 173 grams of pure 

 sodium potassium tartrate and 50 grams of good 

 sodium hydroxid are dissolved in water and the 

 solution made up to 500 c.c. 



Sodium hydroxid ^ /,. 



25 c.c. of the sample in a 500 c.c. flask are 

 diluted with 400 c.c. of water and 10 c.c. of the 

 copper sulfate solution and 8.8 c.c. ^/^ sodium 

 hydroxid solution added. The mixture should 



