26 MILK 
gram of zinc dustisadded. soc.c. of the strong 
sodium hydroxid solution, or sufficient to make - 
the reaction strongly alkaline, should be slowly 
poured down the side of the flask so as not to mix 
at once with the acid solution. It is convenient 
to add to the acid liquid a few drops of phenol- 
phthalein or azolitmin solution, to indicate when 
the liquid is alkaline, but it must be noted that 
strong alkaline solutions destroy the former 
indicator. The flask is shaken so as to mix the 
alkaline and acid liquids and at once attached to 
the condensing apparatus. The receiving flask 
should have been previously charged with a 
carefully measured volume of the N/, acid (10 c.c. 
diluted with distilled water to 100 cc. is a 
convenient amount). The distillation is con- 
ducted until about 150 c.c. have passed over. 
A small amount of indicator is added, the liquid, 
titrated with standard alkali, and the amount 
neutralized by the distilled ammonium hydroxid 
determined by subtraction. Each c.c. of ‘/, 
acid neutralized is equivalent to 0.007 nitrogen. 
The nitrogen multiplied by 6.38 gives the 
total proteins. 
The distillation in this operation requires 
care, as the amount of ammonium hydroxid is 
determined by its neutralizing power, hence 
solution of the alkali of the glass will introduce 
error. Common glassis not satisfactory. Block 
