THE 

 LONDON, EDINBURGH and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE, 



[FOURTH SERIES.] 



DECEMBER 1853. 



LXI. On the Metallic Reflexion exhibited by certain Non-metallic 

 Substances. By Professor G. G. Stokes, M.A., F.R.S.* 



IN the October Number of the Philosophical Magazine is a 

 translation of a paper by M. Haidinger of Vienna, contain- 

 ing an account of his observations relating to the optical pro- 

 perties of Herapathite. In this paper he refers to a communi- 

 cation which I made to the British Association at the meeting at 

 Belfast ; and indeed one great object of his examination of this 

 salt was to see whether a law which he had discovered, and 

 already extensively verified, relating to the connexion between the 

 reflected and transmitted tints of bodies which have the property 

 of reflecting a different tint from that which they transmit, 

 would be verified in this case. The report of my communication 

 published in the Abbe Moigno's Cosmos f had led him to suppose 

 that my observations were at variance with his law. 



My attention was first directed to this subject while engaged 

 in some observations on safnower-red (carthamine), which I 

 was led to examine with reference to its fluorescence. In fol- 

 lowing out the connexion which I had observed to exist be- 

 tween the absorbing power of a medium and its fluorescence, 

 I was induced to notice particularly the composition of the 

 light transmitted by the powder ; and I found that the me- 

 dium, while it acted powerfully on all the more refrangible 

 rays of the visible spectrum, absorbed green light with remark- 

 able energy. I need not now describe the mode of absorption 

 more particularly. During these experiments I was struck with 



* Communicated by the Author. 

 t Vol. i. p. 574. 



Phil. Mag. S. 4. Vol. 6. No. 41. Dec. 1853. 2 D 



