On the Volumetric Relations of Ozone. 549 



March 29, 1860. — Sir Benjamin C. Brodie, Bart., Pres., in the Chair. 



The following communications were read : — 



" On the Volumetric Relations of Ozone, and the Action of the 

 Electrical Discharge on Oxygen and other Gases." By Thomas 

 Andrews, M.D., F.R.S., and P. G. Tait, Esq., M.A. 



This paper contains the full details of the authors' experiments 

 on the volumetric changes which occur in the formation of ozone. 

 From three distinct series of experiments, performed by different 

 methods, they show that when ozone is formed from pure oxygen by 

 the action of the electrical discharge, a condensation takes place, as 

 had already been announced in a former Note published in the 

 • Proceedings/ But the condensation is much greater than the earlier 

 experiments of the authors on the expansion by heat of electrolytic 

 ozone had indicated. It is, in fact, so great, that if the allotropic 

 view of the constitution of ozone be correct, the density of that body, 

 as compared with oxygen, would be represented by a number cor- 

 responding to the density of a solid or liquid rather than that of a 

 gaseous substance. This conclusion follows necessarily from the 

 authors' experiments, unless it be assumed that when ozone comes 

 into contact with such substances as iodine, or a solution of iodide of 

 potassium, one portion of it is changed back into common oxygen, 

 while the remainder enters into combination, and that these portions 

 are so related to one another, that the expansion due to the one is 

 exactly equal to the contraction arising from the other. For the 

 details of the experiments and of the methods of investigation em- 

 ployed, reference must be made to the original paper. 



The second part of the communication is devoted to the action of 

 the silent discharge and of the electrical spark on other gases. 

 Hydrogen and nitrogen undergo no change of volume when exposed 

 to the action of either form of discharge. Cyanogen is readily de- 

 composed by the spark, but presents so great a resistance to the 

 passage of electricity, that the action of the silent discharge can 

 scarcely be observed. Protoxide of nitrogen is readily attacked by 

 both forms of discharge, with increase of volume and formation of 

 nitrogen and hyponitric acid. Deutoxide of nitrogen exhibits the 

 remarkable example of a gas which, under the action either of the 

 silent discharge or of the spark, undergoes, like oxygen, a diminu- 

 tion of volume. It also is resolved into nitrogen and hyponitric 

 acid. Carbonic oxide has given results of great interest; but the 

 nature of the reaction has been only partially investigated. The 

 silent discharge decomposes this gas with production of a substance 

 of a bronze colour on the positive wire. The spark acts differently, 

 destroying, as in the case of oxygen, the greater part of the con- 

 traction produced by the silent discharge. The authors are engaged 

 in the further prosecution of this inquiry. 



" On the Equation of Differences for an Equation of any Order, 

 and in particular for the Equations of the Orders Two, Three, Four, 

 and Five." By Arthur Cayley, Esq., F.R.S. 



