on the Proteolytic Action of Pepsin-hydrochloric Acid. 89 
Stannous chloride. 
This salt shows marked action in retarding gastric digestion; its 
retarding effect increasing directly with the amount of stannous 
chloride added. 
Undigested Fibrin Relative proteo- 
SnCly. residue. digested. lytic action. 
0 0°2576 gram, 74-24 per cent. 100°0 
0-025 per cent. 0:2728 72°72 97°5 
0-1 04826 51°74 69°6 
0°5 0°7332 26°68 35°9 
1-0 0°8155 18°45 24°8 
2°0 0°9010 9:90 15 %3: 
Arsenious oxide. 
This substance might naturally be expected, in view of its well 
known antiseptic properties, to hinder proteolytic action, more 
or less. It is known to hinder putrefaction and to prevent also the 
fermentative action of yeast. Contrary to our expectations, however, 
the action of arsenious oxide, so far as it is to be seen, is an acceler- 
ating one, causing increased proteolytic action. The following 
results were obtained : 
5 Undigested Fibrin Relative proteo- 
A8s9Q3. residue. digested. lytic action. 
0 0:2111 gram. 78°89 per cent. 100°0 
a 0-05 per cent. 01872 81-28 103-0 
O01 0:2160 78°40 99°3 
0-2 0°1900 81:00 102°6 
0°5 ~ 0:1707 82°93 105°1 
The stimulating action is slight, still it is plainly recognizable. 
Drs. Schiifer and Béhm* have previously studied the action of arseni- 
ous acid on the digestion of albumin by artificial gastric juice, and 
they came to the conclusion, using 0°02 and 0:04 gram As,O, respec- 
tively, in 34 c. c. of fluid containing egg-albumin, that arsenious oxide 
is without influence on the decomposition of albumin by the gastric 
juice ferment. Our results, though not so large in number as theirs, 
would indicate a slight accelerating action. 
Arsenic is known, when administered in small, repeated doses, to 
act as a tonic; the history of arsenic-eating, indicates that the sub- 
stance has some positive tonic influence over nutrition, and Dr. 
* Jahresbericht fiir Theirchemie, 1872, p. 363. Ueber den Hinfluss des Arsens auf 
die Wirkung der ungeformten Fermente. 
Trans. Conn. Acap., Vou. VII. 12 Oot., 1885. 
