108 MILK PRODUCTS 
sulfuric acid, and, after boiling, the excess of acid 
is neutralized with standard sodium hydroxid, 
using rosolic acid as indicator. 
Amino-compounds.—These are determined by 
macerating the powdered cheese in water for 
fifteen hours at the ordinary temperature. After 
adding a little dilute sulfuric acid (1: 4), the pro- 
teins and peptones are precipitated by phospho- 
tungstic acid. The precipitate is filtered off and 
washed with water containing a little sulfuric acid. 
The filtrate is made up to a definite bulk, and the 
nitrogen is determined in an aliquot portion of 
the liquid by the Kjeldahl-Gunning process, 
allowance being made for the nitrogen existing as 
ammonium. 
Peptones and Albumoses.—These are deter- 
mined jointly by boiling the powdered cheese 
(mixed with sand as before) with water and 
filtering from the undissolved casein and albumin. 
In an aliquot portion of the filtrate the peptones 
and albumoses are precipitated by adding dilute 
sulfuric acid and phosphotungstic acid. After 
washing with acidulated water the nitrogen in 
the precipitate is determined by the Kjeldahl- 
Gunning process. 
The total nitrogen of the cheese is also deter- 
mined, and after allowing for the nitrogen ex- 
isting as other forms, the remainder is calculated 
to casein, 
