Kithne and Chittenden—Peptones. 293 
1. Amphopeptone prepared with ordinary gastric juice. 
Gastric juice, prepared from 145 grams of isolated mucous mem- 
brane from the fundus of pigs’ stomachs by two days self-digestion 
in two litres of 0°4 per cent. hydrochloric acid, was added to 585 
grams of well washed and boiled fibrin, previously swollen in four 
litres of acid of the same strength and the whole warmed for two 
days more at 40° C. The thin fluid-like mixture so obtained, was 
neutralized with sodium hydroxide and then filtered from the undis- 
solved residue of the mucous membranes (nuclei of the gland cells) 
and the slight neutralization precipitate. After being made slightly 
acid with acetic acid, the fluid was heated to boiling, evaporated to 
two litres, then saturated with neutral ammonium sulphate, separated 
from the slight coagulum and precipitated albumose, again concen- 
trated to one litre and freed from a large portion of the ammonium 
sulphate by crystallization at 0° C. In order to still further separate 
the salt, the solution was treated with one litre of absolute alcohol, 
again placed in the cold, and finally strained through linen to remove 
the fine powdery salt, which was wholly free from precipitated pep- 
tone. After having been freed from alcohol, by vigorous boiling and 
concentration to the consistency of syrup and from much salt by 
crystallization, the thick fluid was filtered by suction, boiled after 
much dilution with a large amount of barium carbonate until the 
odor of ammonia had vanished. From the solution, separated from 
the barium sulphate and again much concentrated, alcohol precipi- 
tated the peptone as a barium compound which could be freed from 
salts (especially sodium chloride) by repeated precipitation and boil- 
ing with alcohol. Finally the barium-peptone was decomposed as 
much as possible with dilute sulphuric acid. As was seen later from 
the concentrated peptone solution, there remained dissolved a trace 
of sulphuric acid, but only enough to make the fluid assume a slight 
opalesceace after boiling with barium chloride and hydrochioric acid. 
An attempt was made to purify the isolated peptone by evaporating, 
precipitating with alcohol, dissolving in water and reprecipitating 
with alcohol. This did not succeed well, as shown later by the high 
percentage of ash. By drying first on a water bath, then in an air 
bath at 105° C. with frequent stirring, which destroyed the firm 
resinous surface, the peptone gradually became solid, and changed 
to a puffed up mass. The resulting product could be ground, when 
cold, to a light, very hygroscopic powder and weighed in this condi- 
tion 25 grams. 
