Solution Tension and Toxicity in Lipolysis. 281 
The point of total inhibition for this concentration is thus seen to 
be 128. Under conditions similar to these lead and copper will show 
exactly the same point. Notable here is the fact that the acidity of 
the control is less than that of the plain reagent at the concentration 
of the plain reagent at which a red precipitate appears upon titration. 
In the control and in the enzyme solution a red precipitate does not 
appear on titration either at 128 orat 64. The protein of the enzyme 
solution prevents the formation of the precipitate, and some of the 
natural acidity of the reagent is probably united to it. 
TABLE XX. 
COPPER. 
M. Reagent Control. Enzyme. Increase. 
65536 0.00 0.20 1.60 1.40 
32768 0.00 0.20 1.60 1.40 
16384 0.00 0.20 1.60 1.40 
8192 0.00 0.20 1.60 1.40 
4096 0.05 0.20 1.50 F639 
2048 0.10 0.20 1.50 1.39 
1024 0.20 0.25 1.00 9-75 
abe 0.40 030 0.90 0.60 
256 0.70 0.50 0.90 0.40 
128 1.40 1.40 1.40 0.00 
64 2.80 2.60 2.60 9.00 
Water ee 0.20 1.60 1.40 
Enzyme, 0.25 per cent. Incubation period, 4 hours. 40° C. 
Notable is the fact that dilutions above 4096 are indifferent, but 
there is no trace of stimulation. As in the case of mercury, the 
acidity of the control is less than that of the plain reagent near the 
point of total inhibition. ? 
| Enzyme, 0.25 per cent. 
TABLE XXI. 
LEAD. 
M. Reagent Control. Enzyme. Increase. 
16384 0.00 0.15 1.40, 1246 
8192 0.00 0.15 1.30 1.15 
4096 0.00 0.15 1.10 0-95 
2048 0.05 0.20 1.10 0.99 
1024 0.10 0.20 1.00 : 0.80 
512 0.20 0.30 1.00 0.79 
256 0.45 0.50 0.90 0.40 
128 0.90 1.00 1.00 0-09 
1.80 1.80 1.80 0.00 
Incubation period, 4 hours. 40° C. 
