162 M. G. Quincke on the Optical Properties 



day's*, however, that he and Warren De la Rue found the colour 

 of the light transmitted by gold to be altered by the employ- 

 ment of polarized light and a set of gypsum plates, it follows 

 that the metallic plates must act somewhat differently from glass 

 plates. The author has arrived at the following results in the 

 course of his research on the properties of the light transmitted 

 through metals. 



When a ray of plane-polarized light is reflected from a metallic 

 surface, the two components of the ray polarized parallel and 

 perpendicular to the plane of incidence undergo a different alte- 

 ration in phase by reflexion. Jaminf has shown that the differ- 

 ence of phase of the components increases from to it (corre- 

 sponding to a difference in the path of the components vary- 

 ing from zero to the length of half an undulation -A if the 



angle of incidence increases from 0° to 90°, i. e. from a perpen- 

 dicular to a grazing incidence. The investigation, carried out 

 w r ith the aid of Babinet's compensator, showed that the compo- 

 nent polarized parallel to the plane of incidence was always acce- 

 lerated in relation to the component polarized perpendicular to 

 the plane of incidence. If the components of the incident light 

 polarized parallel and perpendicular to the plane of incidence 

 were of equal intensity (that is, if the incident ray were polarized 

 under an azimuth a. = 45°), the intensity of the component polar- 

 ized parallel to the plane of incidence always preponderated in the 

 reflected light. 



If a ray of light, polarized in the azimuth a = 45°, be passed 

 through transparent leaves of gold, silver, or platinum, and if 

 the difference of phase of the components be determined by 

 means of a compensator of Babinet's construction, it will be 

 found that (as in reflected light) the component polarized paral- 

 lel to the plane of incidence will predominate over the compo- 

 nent polarized perpendicular to the plane of incidence, and that 

 the difference of phase will be when the incidence is perpen- 

 dicular, and will increase with an increasing angle of incidence. 



The difference of phase of the components is always less in 

 transmitted than in reflected light under the same angle of in- 

 cidence ; and the author has never been able to observe a greater 



TT 



difference of phase than -r, corresponding to a difference of path 

 of j. And in these experiments it makes a difference whether 



* Experimental Researches, vol. iv. p. 394. Employing polarized light 

 and an arrangement of sulphate of lime plates, it was found that other 

 ravs than the green could be transmitted by the gold-leaf. 



t Ann. de Chim. et de Phys. (3) vol. xix. (1847) p. 296; (3) vol.xxix. 

 (1850; p. 282. 



