bo 
— 
Kithne and Chittenden— Peptones. 29 
We have endeavored to prepare pure peptones in quantity from 
the solution saturated with ammonium sulphate. For this purpose 
the solution was first freed from the greater part of the salt by con- 
centration and crystallization. During this process a small amount 
of a nitrogenous substance separated, perhaps albumose formed 
again from peptones when the solution was vigorously boiled and 
the temperature rose to 110° C. The mother liquor, after suitable 
dilution, was boiled with hot saturated baryta water until all ammonia 
was expelled, during waich operation the precaution was taken to 
use no excess of barium hydroxide and thus decompose the peptones. 
From time to time, therefore, portions were filtered, tested for 
sulphate, and when this became small in amount the last portions of 
sulphuric acid were removed by barium carbonate. From the fil- 
trate, which always contained much barium, the latter was entirely 
removed by dilute sulphuric acid, either immediately or after a pre- 
vious purification of the barium peptone compound. The peptones 
were then precipitated with alcohol and occasionally further purified 
with phosphotungstic acid. Naturally the large amount of ammo- 
nium sulphate to be removed formed a correspondingly troublesome 
quantity of barium sulphate, which could be handled only in large 
filtering bags, and occasioned a large loss of peptone in spite of a 
most careful washing of the precipitate with boiling water and the 
application of pressure. On evaporating the peptone solution, which 
contained but little salt, no resinous precipitate resembling albumose 
was to be seen. 
1. Amphopeptone. 
We have designated as amphopeptone the end product of the 
digestion of albumin by pepsin and acid. The first attempt to obtain 
this peptone free from albumose and in a quantity in some degree 
proportionate to our wants, showed us that there was needed not 
only the most active digestive fluid possible and long exposure to a 
temperature of 40° C. but also a very large amount of pepsin. Sach 
a quantity of the ferment could be procured, however, only by first 
dissolving considerable quantities of the mucous membrane of the 
stomach in acid; quantities which must be taken into consideration, 
in addition to the fibrin to be digested, since something is formed in 
the self-digestion of the mucous membrane which necessarily remains 
mixed with the peptone. It is known that mistakes have already 
been committed by not distinguishing the products arising from 
the material of the mucous membrane, from those derived from the 
digested substance. For example, Hoppe-Seyler’s erroneous asser- 
