294 Kihne and Chittenden—Peptones. 
In an attempt to dry the substance for analysis, during which the 
temperature was allowed to rise to 110° C. it was found impossible 
to obtain a constant weight, perhaps on account of decomposition 
setting In, as suggested by an unpleasant odor which had begun to 
develop while on the water bath. Portions of 8-10 grams lost daily 
0:03-0:04 gram. The analyses were accordingly made only after 
drying many days. Portions purified with alcohol, dissolved in 
boiling water with addition of hydrochloric acid, gave no reaction to 
be distinguished when heated with barium chloride. 
Carbon, hydrogen and nitrogen were determined as before, the 
sulphur by a method already used by us to some extent,* viz: by 
fusion with potassium hydroxide and potassium nitrate according to 
the method distinguished by Hammarsten as 1a.+ 
The results of the analysis (Amphopeptone A), shown by the 
following table, were hardly satisfactory and the low percentage of 
carbon, particularly, was quite a surprise to us, hence we proceeded 
at once to the previously mentioned preparation of a peptone, which 
would probably be rendered less impure by derivatives of the 
mucous membrane and which would, moreover, be easier to purify- 
further. 
2. Amphopeptone prepared with purified pepsin. 
Preparation of’ the pepsin.—1220 grams of isolated mucous mem- 
brane from the fundus of ten pigs’ stomachs were warmed at 40° C, 
with seven litres of 0°5 per cent. hydrochloric acid for six days. The 
mixture was then saturated directly with ammonium sulphate, by 
which a resinous precipitate, with large, sticky lumps was formed, 
easily collected on a cloth filter. After pressing out the salt solu- 
tion as much as possible and washing with water, the gummy mass 
was dissolved in five litres of 0°4 per cent. hydrochloric acid and 
warmed again at 40° C. for a few days. Then for the first time it 
was filtered through paper. As preliminary experiments had shown 
that gastric juice which contains small quantities of ammonium sul- 
phate molds easily, the second digestion and the following fibrin 
digestion were carried on in the presence of 0°25 per cent. of thymol, 
which wholly prevented the formation of mold. The mass sub- 
mitted for the second time to self-digestion, gave now with the ammo- 
nium salt a much smaller precipitate, which contained only a very 
* Compare our earlier papers. Zeitschrift fir Biologie, vols. xix and xx. 
+ Zeitschrift fir physiol. Chem., vol. ix, p. 288. 
