90 Chittenden and Allen—Influence of various Salts 
Wood* states, “ there is much reason for believing that it acts largely 
as a direct stimulant to nutrition.” The results obtained in our ex- 
periments certainly accord with this statement. 
Arsenic acid. 
The experiments tried with arsenic acid, tend to confirm the 
accelerating action noticed with arsenious oxide. In the first series 
of experiments the following results were obtained: 
Undigested Fibrin Relative proteo- 
H3As04. residue. digested. lytic action. 
0 0°2696 gram. 73°04 per cent. 100°0 
0-2 per cent. 02614 73°86 LOTS" 
0°5 01514 84°86 1161 
2°0 0°2583 7417 101°5 
5-0 0°3915 60°85 83°3 
\ 
The accelerating action is here so very pronounced, that a second 
series of experiments was undertaken by way of confirmation. These — 
give in a general way the same results, although with 0°5 per cent. the 
stimulating action is not so pronounced as in the first experiment. 
These two series of experiments illustrate another point, which it is 
well to mention here, namely: that definite percentages of any par- 
ticular substance do not invariably give precisely the same result, even 
when compared with their respective controls. They do, however, 
generally point in the same direction, and although not always giving 
exactly the same numerical expression, they show clearly the nature 
and extent of the action. 
: Undigested Fibrin Relative proteo- 
H3AsOq. residue. digested. lytic action. 
0 0°2490 gram. 75°10 per cent. 100°0 
_ 0°2 per cent. 0°2401 75°99 101°2 
0°5 0°2367 76°33 -101°6 
1:0 0°2335 76°65 102°0 
2°0 0°2622 73°78 98°2 
5°0 0°3176 68°24 90°8 
0 071493 85°07 100°0 
10:0 0°4207 57°93 681 
Plainly then, arsenic acid in small percentages does accelerate the 
proteolytic action of pepsin-hydrochloric acid, while in large percent-_ 
ages (5-10) it causes a diminution in the action of the ferment. 
Arsenic acid tends to make the fibrin become very gelatinous. 
* Therapeutics, Materia Medica and Toxicology, p. 390. 
