40 
of N 20 ethyl butyrate were then added and the mixture allowed to 
stand also for twenty-four hours at ordinary temperature in the dark. 
At the end of this time the acid resulting from the hydrolysis was 
titrated with X 10 sodium hydroxide. The results of these experi- 
ments, together with the names of the substances employed and the 
several amounts in milligrams in which they were used, are given in 
the following table: 
_ 
Name of sfSfctance. 
. 
Amount used 
in milligrams. 
Cubic centi- 
meters of 
N 10 sodium 
hydroxide 
required. 
Per cent of 
hydrolysis. 
Water 
None. 
3. 07 
61.40 
Iodic acid 
0. 384 
2. 80 
56.00 
Silver nitrate 
1. 1045 
3. 11 
62. 20 
Mercuric chloride 
3. 521 
1.89 
37. 80 
Chromic acid 
.217 
2. 30 
46. 00 
Perosmic acid 
.4143 
1.62 
32. 20 
Potassium permanganate 
.4112 
.92 
18. 40 
Copper sulphate 
3. 2455 
2. 31 
46. 20 
Potassium nitrite 
1. 1070 
3.03 
60. 60 
Iodine cvanide 
.9945 
.70 
14. 00 
Succinic acid 
. 7670 
3. 00 
60. 00 
Succinic acid peroxide 
1.5210 
. 35 
7.00 
Formic aldehyde 
.1950 
3. 07 
61.40 
Hydrocyanic acid 
. 1755 
2.91 
58. 20 
Trikresol 
.7020 
2.95 
59. 00 
Sodium fluoride 
. 5470 
.06 
1.20 
Chlorine . 
.4608 
0 
0 
Bromine 
1.04 
.10 
2.00 
It is clear from these results that so far as their toxicity or non- 
toxicity to lipase is concerned under the conditions indicated these 
substances fall into several distinct groups. First, those which are 
practically nontoxic, including silver nitrate, iodic acid, formic alde- 
hyde, the cresols, hydrocyanic acid, potassium nitrite, and succinic 
acid. Secondly, those that are moderately toxic, including mercuric 
chloride, chromic acid, copper sulphate, and perosmic acid. Thirdly, 
those that are powerfully toxic, including ozone, chlorine, bromine, 
sodium fluoride, succinic peroxide acid, iodine cyanide, and potassium 
permanganate. It is interesting to note that the first two groups con- 
tain a number of substances highly toxic to many living forms, 
whereas, with one exception, the last group is composed of powerful 
oxidizing agents. 
TOXICITY AND TEMPERATURE. 
It has also been observed that the toxicity of iodine cyanide to lipase 
is increased by rise of temperature. That such is the case is evident 
from the following results: 
Two series of experiments with this substance were carried out, one 
at 10° C. and the other at 10° C., in which 1 cc. of water, or 1 cc. of an 
