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 
