268 Raymond FH. Pond. 
TABLE IV. 
CADMIUM. 
M. Reagent. Control. Enzyme. Increase. 
2048 0.00 0.00 0.20 0.20 
1024 0.00 0.03 0.20 0.17 
512 0.00 0.05 0.20 0.15 
256 0.00 0.10 0.20 0.10 
128 0.05 0.20 0.20 0.00* 
64 0.10 0.30 0.30 0.00** 
CoBALT. 
2048 0.00 0.10 0.20 0.10 | 
1024 0.00 0.15 0.25 0.10 
512 0.00 0.20 0.25 0.05* 
256 0.02 0.25 0.30 0.05 ** 
128 0.05 0.30 0.30 0.00%** 
ZINC. 
2048 0.10 0.15 0.25 0.10 
1024 0.20 0.30 0.40 0.10* 
512 0.45 0.50 0.50 0.00** 
256 0.90 0.90 0.90 0.00*** 
Enzyme, 0.0125 per cent. Incubation period, 18 hours. 40° C. 
This test was repeated the following day with only insignificant 
variations, the digestion period being only twelve hours. 
It is very clear that zinc is more toxic than cadmium or cobalt. 
The amount of saponification allowed by zine and cobalt at 2048 and 
at 1024 is, however, exactly the same, while cadmium at 2048 does 
Not at all inhibit. On this basis zinc and cobalt are equal in toxicity, 
and both are more toxic than cadmium. In other cases it will be 
seen that relative toxicity based upon the concentration of total in- 
hibition gives a different relation from that based upon the maximum 
concentration not inhibiting. This fact has been disregarded’ in con- 
cluding as to the relative toxicity and only the points of total inhibi- 
tion compared. 
* Indicates the first appearance of a precipitate on titration, and the extra stars 
mean increasing quantity of precipitate. 
