QUANTITATIVE DIGESTION EXPERIMENTS 243 



sodium chloride solution in order to completely precipitate all 

 the albumin. Then let cool, place the entire fluid together with 

 the precipitate in a 100- or 200-cc. measuring-flask, rinse the 

 vessel thoroughly, fill up to the mark, filter through a dry 

 filter, and take a quarter or half of the whole amount for the 

 nitrogen determination. 



The amount of nitrogen contained in the pepsin-hydro- 

 chloric acid is so small that it may be neglected. It must be 

 considered, however, when an extract of the mucus membrane 

 of the stomach is used. Of course the amount of nitrogen 

 in the substance tested is also to be taken into consideratiou . 



It is not always possible to proceed as above ; quite often 

 the method must be modified. For the arrangement of 

 these experiments see Yirchow's Arch. 120, 353; 122, 238; 

 127, 514; Berl. klin. Wochenschr. 1891, No. 32; Virchow's 

 Arch. 150, 260 (1897). 



