DR. ANDREWS ON THE CONSTITUTION AND PROPERTIES OF OZONE. 
13 
oxidable substances in solution, as the protosulphate of iron, are raised to a higher 
state of oxidation by all the varieties of ozone. 
It would not be difficult to extend this comparison, but enough has been shown, I 
conceive, to establish the absolute identity in properties of ozone in whatever way it 
may be prepared. Any difference which, on a superficial examination, may appear 
to exist, will be found on further inquiry to arise from the ozone being in a more or 
less dilute state. 
That ozone is formed by the action of the electrical spark on perfectly dry oxygen, 
is placed beyond all doubt by the following experiment. The curved tube a, fig. 5, 
having two platina wires, pp' , hermetically sealed into it, was inverted over mercury 
and carefully filled with pure oxygen, after which a little sulphuric acid was intro- 
duced into one end {h). The whole was allowed to remain for twenty-four hours, 
when the oxygen was considered to be perfectly dry. Electrical sparks were now 
passed for some time between the platina wires, after which a solution of iodide of 
potassium was introduced into the other end of the tube. It became immediately 
coloured from the formation of free iodine, and the colour continued slowly to 
increase as the ozone was gradually absorbed. 
Again, a solution of iodide of potassium may be made to absorb the whole of the 
oxygen in a narrow tube, by the passage of electrical sparks. This experiment 
has been described by Fremy and Becquerel, and I have myself repeatedly verified 
its accuracy. With a thermometer tube 2 inches long, the whole of the oxygen may 
be made to disappear in the course of one minute. The solution becomes always 
red from the decomposition of the iodide of potassium. 
We have already seen that neither hydrogen nor nitrogen can be constituents of 
ozone, whether it be obtained from electrolysis, or from the action of the electrical 
spark on oxygen ; and further, that all the supposed varieties of ozone exhibit in all 
respects identical properties. 
Connecting all these facts together, it clearly follows, — 
That no gaseous compound having the composition HO 3 is formed during the 
electrolysis of water ; and 
That ozone, from whatever source derived, is one and the same body, having 
identical properties and the same constitution, and is not a compound body, but 
oxygen in an altered or allotropic condition. 
