on the Proteolytic Action of Pepsin-hydrochloric Acid. 91 
Zine sulphate. 
With this salt, no experiments appear to have been hitherto made. 
Our results show a decided diminution in proteolytic action, even in 
the presence of 0°01 per cent. of the salt, while with a few thou- 
sandths of one per cent. the figures indicate a slight accelerating 
action. Three distinct experiments were made as follows: 
Undigested Fibrin Relative proteo- 
ZnSO4+%7H 20. residue. digested. lytic action. 
0 0°1744 gram. 82°56 per cent. 100°0 
0-001 per cent. 0°1609 83°91 101°6 
0°005 01617 83°83 101°5 
0°010 0°2053 79°46 96°2 
0°025 0°2573 74:27 89-9 
3°000 0°8400 16°00 EOS 
0 0°1630 83°20 100-0 
0-1 0°4848 51°52 61°9 
0°3 0°7133 28°67 34°4 
0°5 0°7382 26°18 31-4 
0°8 O:'T671 23°29 27:9 
1:5 0°8202 17-98 21°6 
0 071493 85:07 100:0 
1:0 0:7683 23°17 27°2 
A glance at these results, shows plainly a gradual decrease in pro- 
teolytic activity. 
It is to be noticed that in the presence of the larger percentages of 
these metallic salts, the fibrin does not swell up in the 0:2 per cent. acid. 
Manganous chloride. 
In small fractions of one per cent. this salt gave such irregular 
results that it is doubtful if they can be relied upon as expressing 
any particular action. With 0°3 per cent. the retarding action of 
the manganese salt commences to be very pronounced. Following 
are the results: 
Undigested Fibrin Relative proteo- 
MnCly. residue. digested, lytic action 
0 01923 gram. 80°77 per cent. 100°0 
0-001 per cent. 0°2022 79°78 98°7 
0:010 0°1815 81°85 101°3 
0°025 0°2066 79°34. 98-2 
0:050 071855 81°45 100°8 
0 0°1880 81°20 100°0 
0°3 0°3687 63°13 SoS 
08 0°6438 35°62 43°8 
15 0°6612 33°88 41:7 
3-0 0°7400 26°00 32°0 
