452 M. E. Joclimann on the Reflection and Refraction 



freezing of water under the reciever of an air-pump) is so 

 great that it might almost claim recognition from chemists as 

 due to a " chemical affinity," and resulting in a " chemical 

 combination," I believe that the absorption of vapour into 

 fibrous and cellular organic structures is a property of matter 

 continuous with the absorption of vapour into a capillary tube 

 demonstrated above. 



LXI. On the Reflection and Refraction of Light by thin Layers 

 of Metal. By E. Jochmann*. 



THE optical properties of thin metallic lamellae have recently 

 been subjected by Quincke to a series of careful and in 

 many ways varied experimental investigations f. The remark- 

 able and in part unexpected results of these investigations make 

 sensible a deficiency in the theory of reflection, in that the theory 

 of the interference-phenomena of thin transparent lamellae has 

 not hitherto been extended to metallic media. Starting from 

 the principles of Cauchy's theory of reflection, I arrived at a 

 system of formulas which represent the phenomena of reflection 

 and refraction of light by thin metallic lamellae with the same 

 degree of mathematical accuracy as the formulae of Cauchy for 

 metallic reflection on the supposition of a considerable thickness 

 of the metallic layer. Cauchy's formulae for the intensity and 

 phase of light polarized perpendicular to the plane of incidence 

 include, as is known, the simplifying presupposition that the 

 coefficient of ellipticity e (originating from the influence of the 

 longitudinal waves) may be put equal to 0. We know that the 

 influence of this coefficient with transparent media is always but 

 very little, except in the vicinity of the angle of polarization. 

 With metals there is no polarization-angle in the same sense as 

 with transparent media; and indeed the comparison ofCauchy's 

 formulas with experiment teaches that the influence of the coeffi- 

 cient of ellipticity may, without sensible error, be neglected, even 

 with metallic media. So much the more will this presupposition 

 be justified when the theory is applied to thin metallic lamellae, 

 in which manifold causes cooperate diminishing the accuracy 

 attainable by the measurements. Although the method which 

 I have used for the derivation of the following formulae permits 

 the carrying out in full rigour the solution of the problem, yet 

 it appeared useful, in the case of light polarized perpendicular to 

 the plane of incidence, to introduce that simplifying presuppo- 

 sition, in order to give to the formulae a form applicable to the 



* Translated from a separate copy, communicated by the Author, from 

 Pogg. Ann. Erganzungsband v. pp. 620-6*35. 



•f Pogg. Ann. vol.cxxviii. p. 54 1 ; vol. cxx x. pp.44 & 1 77; vol. cxxxii.pp. 

 29, 204, 32 1 & 56 1 . Nachrichten d. Gdttinger Ges. d. Wissmsch. Dec. 21,1 870. 



