1859.] General Monthly Meeting. 163 



fully shown. The first or immediate light of the body is often of one 

 colour, whilst on the cessation of the discharge the second or deferred 

 light is of another ; and many variations of the effects can be pro- 

 duced. 



In connexion with rarefied media it may be remarked, that some of 

 the tubes by Geissler and others have been observed to have their 

 rarefied atmospheres phosphorescent, glowing with light for a moment 

 or two after the discharge through them was suspended. Since then 

 Becquerel lias observed that oxygen is rendered phosphorescent, i.e. 

 that it presents a persistent effect of light, when electric discharges are 

 passed through it. I have several times had occasion to observe that a 

 flash of lightning, when seen as a linear discharge, left the luminous 

 trace of its form on the clouds, enduring for a sensible time after the 

 lightning was gone. I strictly verified this fact in June, 1857, record- 

 ing it in the *' Philosophical Magazine,"* and referred it to the phos- 

 phorescence of the cloud. I have no doubt that that is the true 

 explanation. Other phenomena, having relation to fluorescence and 

 phosphorescence, as the difference in the light of oxygen and hydrogen 

 exploded in glass globes, or in the air, were referred to, with the 

 expression of strong hopes that Becquerel's additions to that branch of 

 science would greatly explain and extend them. 



[M. F.] 



GENERAL MONTHLY MEETING, 



Monday, July 4, 1859. 



Colonel Philip James Yorke, F.R.S. Vice-President, 

 in the Chair. 



Thomas Harlin, Esq. M.A. 



James Merryweather, Esq. M.R.C.E. and 



James Watney, Esq. 



were duly elected Members of the Royal Institution. 



The Special Thanks of the Members were returned to His Royal 

 Highness the Prince Consort, for his present of the works of Kuhl- 

 mann and Von Fuchs on Water-Glass, which have been translated and 

 printed for private circulation, by command of His Royal Highness ; 

 and to Sir John Rennie, for his present of his work on the Break- 

 water in Plymouth Sound. 



* Philosophical Magazine, June, 1857, p. 506. 



