102 Chittenden and Allen—Influence of various Salts 
Wolberg in speaking of the relative retarding action of the three 
sodium salts of hydrochloric, nitric and sulphuric acids, states that 
the sulphate retards the most, then the nitrate and lastly the chloride. 
We have noticed the same fact in our work and take it as additional 
evidence of the liberation of the acid of the salt added, the retarding 
influence of the salt being dependent, in part, on the digestive power of 
the pepsin-acid formed. 
The following experiments,* showing the relative digestive power 
of the several acids in conjunction with pepsin, testify to the proba- 
bility of this view. 
All of the solutions contained 50 c. c. of an aqueous solution of 
glycerine-pepsin, each having a total volume of 100 c. c. and differing 
from each other only in the nature and percentage of the acid present. 
In testing the digestive power of the solution, 1 gram of pure fibrin 
was added and the mixtures warmed at 40° C. for two hours, after 
which the amount digested was determined in the usual manner. 
Percentage of fibrin digested in the presence of the different per- 
centages of acids. 
Control. 
0°05% O-1% 0:2% O38 G O4% 05% 0:°1% HCl 
HNOst-.-. 9°20 48°75 73°65 67°20 46:00 87°65 
SO. 19°50 24°70 25°80 22°55 24°95 88°05 
CeHuOsas-- 3°70 2°30 87°50 
Comparing these results with their respective controls, figured as 
100, we have the following values for sulphuric and nitrie acids, ex- 
pressive of their relative proteolytic power when combined with 
pepsin, as compared with 01 per cent. hydrochloric acid under simi- 
lar conditions. 
Per cent. acid. HNO3. H2S804. 
0°05 10°5 Atta § 
01 55:5 22°1 
0°2 84:0 28°0 
03 767 29:1 
04 52°5 25°6 
0°5 eee 28°2 
From this it is evident, that nitric acid is most active, with our 
amount of pepsin, in a 0°2 per cent. solution, while sulphuric acid 
attains its maximum action in 0°3 per cent.; moreover, nitric acid is 
* Made in this laboratory by Mr. R. W. Pinney. 
+ The acids are calculated as pure HNOs, H.SO,, ete. 
