Uranium Salts on Ferment Action. 267 
Following are the results obtained with the various salts : 
Uranyl nitrate. 
Relative 
UO.(NO;)2+6H.O. Undigested residue. Fibrin digested. proteolytic action. 
0 0°1858 gram. 86°47 per cent. 100-0 
0-025 per cent. 0°1865 86°35 99°8 
0-050 0:13878 86°22 99-7 
0:100 0°2397 76°03 87°9 
0°500 0°5008 49°97 57°8 
1-000 0:6638 33°62 38°8 
Uranyl acetate. 
U0.2(C2H302)2 Relative 
+H,0. Undigested residue. Fibrin digested. proteolytic action. 
0 0°1453 gram. 85°47 per cent. 100-0 
0:025 per cent. 0°1581 84°19 98°5 
0-050 0:°1867 81°33 95:1 
0-100 0:2052 79°48 92°9 
0-500 Oa" 24°98 29:2 
1-000 1:0050 0 0 
It is to be noticed here, that the retarding action of the acetate, as 
with saliva, is far greater than the nitrate, a fact which is doubtless 
dependent in this case on the nature of the acid united with the ura- 
nium. Further, it is to be noticed, that the action of uranyl sulphate 
falls about midway between the action of the nitrate and acetate. 
These facts accord with views previously* expressed, and show 
plainly that the extent of the retarding action of salts in general is 
dependent in part, of the liberation of the acid of the salt and the 
digestive power of the pepsin-acid formed. Experiments have shown 
that nitric acid of appropriate strength, united with pepsin, is about 
four-fifths as active as hydrochloric acid, while sulphuric acid is only 
a little more than one-fourth as active as hydrochloric of the same 
strength and that acetic acid is practically inactive. Hence, the 
base being the same, acetates, citrates, and other salts, the acids of 
which are not capable of working with pepsin will most readily retard 
gastric digestion. This view being correct, uranyl nitrate, sulphate 
and acetate should retard gastric digestion in just such relative pro- 
portion as our experiments show they actually do. 
* See Studies from this Laboratory, 1884-85, p. 94-95, 
