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VII. On the Volumetric Relations of Ozone, and the Action of the Electrical Discharge 
on Oxygen and other Gases. By Thomas Andeews, M.D., F.R.S., M.R.I.A., Vice- 
President of Queens College, Belfast-, and Petee G. Tait, M.A., late Felloio of 
St. Peters College, Cambridge, Professor of Mathematics in Queens College, Belfast. 
Eeceived February 20,— Bead March 29, 1860. 
M- 
The molecular changes produced by the electric current, or discharge, in certain com- 
pound bodies through which it is transmitted, furnish some of the most interesting- 
examples of the action of a decomposing force that have been discovered in later times. 
The discharge of the Leyden jar, through fine wires or thin metallic leaves, exhibited 
long ago the heating power of the current, and the interesting experiments of the Dutch 
chemists afterwards showed that the disruptive discharge has the power of splitting up 
compound bodies into their constituent parts. The great invention of the pile of Volta, 
by famishing an abundant supply of electricity of moderate tension, led subsequently to 
the important discovery of the polar decomposition of water and of other compound 
bodies. In the case of gases, it has been known, since the time of Peiestley and 
Cavendish, that the spark discharge has the apparently antagonistic properties of 
causing decomposition in some cases and combination in others. Finally, in our own 
day, ScHONBEiN made the fine observation that a new substance (ozone), alike remark- 
able for the activity of its properties and for the facility with which it is destroyed, is 
formed by the action of the spark on pure oxygen gas, in the electrolysis of water, and 
in certain cases of slow oxidation. 
Our object in the present communication is to continue the investigation, already 
begun by one of us*, of the properties of ozone, by subjecting it under varied conditions 
to a series of careful volumetric experiments. We hoped, in this way, to throw some 
new light on the relations of this singular body to oxygen, by determining whether any, 
and what, change of volume occurs in its formation. Our expectations in this respect 
have not been disappointed. We have ascertained that when oxygen changes into 
ozone, a great condensation takes place ; so great indeed, that it is almost incompatible 
with the existence of ozone as an allotropic form of oxygen in the gaseous state. This 
investigation has naturally extended itself to an examination of the effects produced by 
the electrical discharge upon other gases, simple as well as compound ; and although, 
from its great extent, this part of the inquiry has as yet been only partially entered into. 
* Philosophical Transactions, 1856, p. 1. 
