416 M. Verdet on the Optical Properties developed in 



fraction were measured by Babinct's goniometer, the liquids 

 being enclosed in an excellent gluss prism, whose refracting angle 

 was 43° 41', constructed by M. Erunner. 



This series of experiments showed me that there is no simple 

 relation between the refractive indices and the magneto-rotary 

 powers. This will be seen by referring to the following Table, 

 where the results of my experiments are given, the several 

 liquids being arranged according to their progressive refractive 

 indices. 



Table I. 



Liquids. 



Refractive 

 Indices. 



1-334 

 1-341 

 1-354 

 1-35.') 

 1-355 

 1-357 

 1-359 

 1-364 

 1-368 

 1-370 

 1-371 

 1-372 

 V378 

 1-394 

 1-424 

 1-448 

 Chloride of carbon, C- CI-" 1 I'-ieO 



Distilled water 



SoUnioii of borate of soda 



cliloride of calcium . . . 

 carbonate of potash . . . 



nitrate of lead 



chloride of magnesium, 

 chloride of annnonium . 

 protocliloride of fin . . . 



chloride of zinc 



chloride of ammoninm . 

 carbonate of potash . . . 

 chloride of calcium . . . 

 protochloride of tin . . . 



chloride of zinc. '■ 



protochloride of tin . . 

 nitrate of ammonia 



Magneto-rotary 

 Powers. 



1-000 

 1000 

 1085 

 1-050 

 1000 

 1-127 

 1-184 

 1-348 

 1-341 

 1-371 

 1-087 

 1-230 

 1-525 

 1-507 

 2-047 

 0-908 

 1-264 



It is seen from this Table that the order of the refractive 

 indices is quite different from that of the magneto-rotary powers. 

 Thus, merely to adduce the most striking cases, nitrate of am- 

 monia, whose magneto-rotary power is the most feeble of all 

 those given, has one of the highest refractive indices. Again, 

 chloride of carbon, which is more refractive than any of the 

 solutions of protochloride of tin examined, has a less magneto- 

 rotary power than the least concoitratcd of these three solutions. 

 The solutions again of chloride of calcium, carbonate of potash, 

 and of chloi'ide of ammonium, whose refractive indices arc almost 

 equal, have very widely different magneto-rotary powers. 



The law enunciated by M. De la Hive is therefore not sup- 

 ported by experiment, and the magneto-rotary powers of bodies 

 do not appear to depend exclusively upon tlie constitution of 

 the fethcr which they contain. The question natiirally suggests 

 itself, whether such rotary powers do not rather depend upon 

 the diamagnetic properties of bodies, — whether, for instance, as 



