32 MILK 
For amino-derivatives and ammonium com- 
pounds, 50 c.c. of the milk are mixed in a flask 
marked at 250 c.c. with 1 gram of sodium chlorid. 
A 12% solution of tannin is added, drop by drop, 
until 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 so 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. X/, sodium 
hydroxid solution added. The mixture should 
