Uranium Salts on Ferment Action. 271 
3. Influence on the proteolytic action of trypsin. 
The method employed in determining the extent of proteolytic ac: 
tion in this case was much the same asin the preceding. The trypsin 
solution was made as neutral as possible and was prepared from dried 
OX pancreas, previously extracted with alcohol and ether; 20 grams 
dry pancreas, extracted with 200 c.c., 0°1 per cent. salicylic acid and 
ultimately diluted to 1 litre. A little thymol was added to prevent 
decomposition. 50 ¢.c. of the trypsin solution were used in each ex- 
periment, together with 1 gram of prepared fibrin and the necessary 
amount of uranium salt. 
The first experiment was tried with uranyl nitrate, the mixtures 
being warmed at 40° C. for six hours. Following are the results : 
Relative 
U0.(NOs3)2+6H20. Undigested residue. Fibrin digested. proteolytic action , 
0 0°2927 gram. 70°73 per cent. 100°0 
0-010 per cent. 0°3328 66°72 94:3 
0-025 0:3460 65:40 92:4 
0-050 0°4198 58-02 | 82-0 
0-100 05004 49-96 70°6 
0°500 a 0 0 
With this salt retarding action is seen to be gradual upto a certain 
point, and then suddenly all ferment action ceases. 
Uranyl acetate. 
U0.(C2H302)2° Relative 
+ H,0. Undigested residue. Fibrin digested. proteolytic action. 
0 0-4234 gram. 57°66 per cent. 100-0 
0:010 per cent. 0°4591 54:09 93°8 
0-025 0:5460 45°40 18°77 
0-050 0°6094 39°06 67°7 
0-100 0°8173 18.27 31°6 
0°500 0 0 
This series of experiments was warmed at 40° C. for about five 
hours. The inhibitory action of the salt is seen to be more pro- 
nounced than that of the nitrate; indeed, there is to be seen here, 
the same difference in action noticed in the case of the amylolytic 
ferment. 
Uranyl sulphate. 
With this salt, under exactly the same conditions of time and 
temperature as the preceding, the following results were obtained : 
