CHEESE 107 



magma that can be measured with a pipet. The 

 quantity of copper hydroxid per c.c. should be 

 determined. It should be kept in a well-closed 

 bottle. 



Ammonium compounds. — ^About 5 grams of 

 cheese are rubbed up in a mortar with water, 

 transferred to a filter, and washed with a liter 

 of cold water. The filtrate is concentrated by 

 boiling (if alkaline, it must be neutralized before 

 heating), barium carbonate added, the liquid 

 distilled, and the ammonium hydroxid in 

 the distillate estimated by titration with stand- 

 ard acid. 



According to Stutzer, magnesium oxid or 

 magnesium carbonate (the latter usually contains 

 some oxid) should not be used as some of the 

 amino-compounds may be decomposed. 



Amino-compounds. — The nitrogen as amino- 

 compounds is estimated by subtracting from 

 the figure for total nitrogen the sum of the 

 protein and ammoniacal nitrogen. If nitrates 

 are present, the nitrogen as such should also be 

 determined and subtracted. 



Van Ketel & Antusch propose the following 

 methods for estimating the nitrogen compounds: 



Ammonium compounds. — The sample, pow- 

 dered with the addition of sand, is distilled with 

 water and barium carbonate, and the distillate 

 received in a measured quantity of standard 



