THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZ INE 



AND 



JOURNAL OF SCIENCE. 



[FOURTH SERIES.] 



MARCH 1864. 



XXIX. On the Optical Properties of the Metals. 

 By G. Quincke*. 



X^IZHILST physicists have for some time back occupied 

 ▼ ▼ themselves with the properties of the light reflected 

 from metals, they have paid very little attention to light pass- 

 ing through metals — a circumstance partly to be ascribed to the 

 technical difficulties of the preparation and manipulation of thin 

 transparent metallic plates. The little that one knows about 

 the light transmitted through metals, as, for instance, the results 

 of Faraday's f recent researches, refers almost entirely to the in- 

 tensity and colour of the light. The latter shows itself to be so 

 very inconstant for the same metal, that one would be disposed 

 to seek the explanation of the irregularity in the presence of 

 holes in the metallic plate, if Faraday had not demonstrated 

 this property of a thin metallic film, viz. that when placed ob- 

 liquely between two crossed NicoFs prisms, it illuminates the 

 field and acts "just like a glass plate." 



This property of thin transparent plates of metal was, so far 

 as the author knows, first observed by Warren De la RueJ with 

 regard to gold-leaf, and afterwards by Faraday in thin trans- 

 parent plates of platinum, palladium, rhodium, silver, copper, 

 tin, lead, iron, zinc, and aluminium §. From a remark of Fara- 



* Translated by Professor Wanklyn from PoggendorfF s Annalen, 

 vol. cxix. part. 3 (1863, No. 7). 



t Phil. Trans. 1857, p. 145. Experimental Researches in Chemistiy 

 and Physics, vol. iv. p. 391. 



\ Faradav, ' Experimental Researches,' vol. iv. p. 401. 



§ Ibid. p. 441. 



Phil. Mag. S. 4. Vol. 27. No. 181. March 1864. M 



