VARIETIES. 
75 
the oxidation of the potassium by the ozone, and the setting free of the 
iodine. This is one of the best tests for the presence of ozone. It was 
formerly supposed that nitric acid was produced by the discharge of the 
spark, and that the decomposition of the iodide was occasioned by this acid 
as a result of the union of oxygen with nitrogen in the air: but this theory 
will not account for the smell and other properties of this extraordinary 
agent. 
Schonbein produces ozone in very large quantities by introducing into 
capacious bottles, with glass stoppers, pieces of cut and clean scraped phos- 
phorus, with small quantity of water, so that the phosphorus may be 
partly in and partly out of the liquid. A vapor slowly rises in a current. 
After ten or twelve minutes the ozone is produced, and may be procured in 
admixture with oxygen and nitrogen by removing the phosphorus at a pneu- 
matic trough, and thoroughly washing the interior of the bottle with water, 
in which ozone is insoluble. This body is thus separated from the vapor of 
phosphorus and phosphorous acid. (This experiment was performed in three 
bottles and several bottles of ozone previously prepared were now brought 
forward.) On introducing paper, wetted with starch and iodide of potas- 
sium, into one of the bottles, there was an immediate indication of the 
presence of this principle, by the production of a dark blue iodide of starch. 
Another remarkable property possessed by ozone was seen in its bleaching 
powers. Some ounces of a solution of sulphate of indigo were gradually 
poured into a bottle containing ozone, and shaken, when the color was as 
completely destroyed as if chlorine or chloride of lime had been present. 
A very small quantity of ozone would thus entirely discharge the color of 
a very large quantity of sulphate of indigo. 
It has been already stated to be so little soluble in water, that a bottle 
containing it may be repeatedly rinsed with water without losing its ozonic 
contents. If, however, the stopper be removed, and it is exposed to air, it 
soon passes off. Ozone appears to be entirely destroyed by heat ; or, at 
any rate, its production by electricity ceases when sparks are received from 
a red-hot metallic point. This fact was ingeniously illustrated by insulat- 
ing a small galvanic battery, capable of raising at pleasure a platina ball 
to full redness ; the battery was made part of the machine, and the platina 
ball the terminal point from which the discharges of electricity were re- 
ceived. The machine was set to work, and it was clearly and distinctly 
proved by Professor Faraday that the discharges from the red-hot platina 
ball produced neither the aura, the smell nor the decomposing effects 
on iodide of potassium and starch which were immediately manifested 
when the ball was allowed to cool, and the electric fluid was then passed 
through it. 
The oxidizing properties of ozone are indicated upon metals which in 
practice it is rather difficult to convert to oxides, namely, silver. A piece 
of polished silver had been placed in a bottle of ozone for several hours, 
