﻿THE 



LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[FIFTH SERIES.] 



DECEMBER 1894. 



LXI. On the Rate of Oxidation of Phosphorus, Sulphur, and 

 Aldehyde. By Thomas Ewan, B.Sc, Ph.D., late 1851 

 Exhibition Scholar in Chemistry at the Owens College*. 



Introduction. 



ACCORDING to our present knowledge the velocity with 

 which a chemical change takes place is dependent on 

 the concentrations of the substances taking part in the change, 

 and the connexion between the two is of such a nature that 

 a greater concentration corresponds to a greater velocity. 



Under these circumstances it is of great interest that in a 

 number of instances oxygen gas appears to act chemically 

 more vigorously, that is with greater velocity, when it is 

 dilute than when it is more concentrated. 



The first mention of this behaviour, so far as I know, was 

 made by Fourcroy f. He says that at the ordinary tempe- 

 rature and pressure pure oxygen is without action on phos- 

 phorus, although ordinary air acts vigorously. In 1798 van 

 MarumJ found that a piece of phosphorus glowed much 

 more brightly in rarefied than in ordinary air, and that it 

 even took fire at very low pressures if surrounded by a little 

 cotton-wool. These observations were confirmed and extended 

 by subsequent observers. 



* Communicated by the Author, 

 f Memoir -es de VAcademie des Sciences, 1788. 



| Verhandelingen uitgegeeven door Teyler's Ttaeede Genootschap, 10 

 (1798). 



Ptel. Mag. S. 5. Vol. 38. No. 235. Dec. 1894. 2 M 



