on the Proteolytic Action of Pepsin-hydrochloric Acid. 85 
@ 
Our aim has been, therefore, to study more particularly the com- 
parative influence on gastric digestion of various percentages of 
those salts, well known as poisons or therapeutic agents, which have 
hitherto been overlooked or but imperfectly studied. At the same 
time in order to make the work more complete, we have studied 
somewhat, the action of the alkali salts, experimented with by other 
observers. 
Method employed. 
The experiments were conducted in series, in which one of each 
series served as a control for comparison. The artificial gastric juice 
employed, was made from 0:2 per cent. hydrochloric acid and a 
glycerine extract of pepsin, in the proportion of 10 ¢.c. of the latter 
to 1 litre of the former. The volume of each digestive mixture was 
50 c.c.; made up of 25 c.c. of the above-mentioned gastric juice and 
25 ¢.c. of 0°2 per cent. hydrochloric acid, containing the salt to be 
experimented with. The material to be digested, consisted of puri- 
fied and dried blood-fibrin, prepared by thorough washing with 
water, extraction with cold and boiling alcohol and lastly with ether. 
It was then ground to a coarse powder and dried at 100-110°C. 1 
gram of the fibrin was used in each experiment. The digestive mix- 
tures were warmed at 40° C. for two hours, then filtered upon 
weighed filters by the aid of pumps, the residue washed thoroughly 
with water, lastly with alcohol, and finally dried at 100-110° C. until 
of constant weight (48 hours). The amount of fibrin digested or dis- 
solved, is a measure of the proteolytic action. 
Cupric sulphate. 
With this salt two series of experiments were made; one to ascer- 
tain the influence of small quantities, the other to show the effects of 
larger amounts of the substance. 
7 Undigested Fibrin Relative proteo- 
CuS04+5H20. residue. digested. lytic action. 
0 0°2854 gram. 71°46 per cent. 100°0 
0°001 per cent. 0°2508 74:92 104°8 
0°005 0°2650 73°50 102°8 
07010 0°3067 69°33 970 
0:025 0°3845 61°55 86°] 
0°050 0°3877 61°23 85°6 
0 0°2352 76°48 100°0 
0'1 0°5315 46°85 61°2 
0°3 0°7585 24°15 31°5 
0°5 0-7976 20°24 26°4 
0'8 0°8214 17°86 23°3 
15 0°8480 15°20 19°8 
