THE TOXICITY OF OZONE AND OTHER OXIDIZING AGENTS TO LIPASE. 
My attention was directed to the general subject of the toxicity of 
ozone through a few observations that were made in my laboratory 
on the odor of this substance. On being asked to describe the odor of 
small amounts of ozone, two out of six persons, not chemists, described 
it as similar to that of hydrocyanic acid. Considering the great differ- 
ence in the chemical composition of the two substances, this in itself 
is interesting, and at once suggested the idea that possibly ozone, like 
hydrocyanic acid, might be a protoplasmic poison. In fact, it is known 
to be an irritant poison to higher animals. It is also toxic to micro- 
organisms, and recently it has been shown by Sigmund 0 to be poison- 
ous to a number of unorganized ferments, such as invertase, pepsin, 
emulsin, etc. It therefore occurred to me that it might prove of inter- 
est to test its toxicity toward lipase, inasmuch as but few substances 
except hydrofluoric acid and the fluorides exert any powerfully toxic 
action on this ferment, particularly on that obtained from the liver of 
the hog. 
The ozone used in these experiments was obtained by the electro- 
lysis of water containing sulphuric acid. The gas liberated at the anode 
during the electrolysis was collected in a series of 50 cc. measuring 
flasks, and the amount of ozone determined in the first and last flasks 
of a series by passing the gas through a solution of potassium iodide 
and titrating with X 50 sodium thiosulphate. The ozone in 50 cc. of 
the gas first employed in these experiments liberated an amount of 
iodine equivalent to 0.65 cc. of N 50 sodium thiosulphate. This is 
equivalent to 0.312 milligram of ozone in 50 cc. or 6. 2d milligrams 
of ozone per liter. 
The effect of this amount of ozone on a clear solution of hog liver 
lipase, prepared according to the method described by Kastle, John- 
ston. and Elvove, * & was tested in the following manner: 
Five cubic centimeters of the clear lipase solution was introduced into 
each of two glass-stoppered flasks; one of these, No. 1 , contained 0.312 
milligram of ozone; the other, No. 2, xvas filled with atmospheric air. 
The flasks were then closed and sealed with paraffin and kept in a 
dark closet, at ordinary temperature, for twenty -four hours. At the 
end of this time the odor of the ozone had entirely disappeared from 
a Centr. Blatt. f. Bact. (2) Bd. XIV, Xos. 12, 13. 
6 Am. Chem. Jour. XXXI, p. 525. 
