Dec. 1 845.] Action of Magnets on Diamagnetic Bodies. 403 



nected will), the same condition of the glass as made it then 

 effective, and therefore, with those phenomena, prove the 

 reality of this new condition. 



If iii. Action of magnets on other substances acting magneti- 

 cally on light. 



2275. We may now pass from heavy glass to the examina- 

 tion of the other substances, which, when under the power of 

 magnetic or electric forces, are able to affect and rotate a po- 

 larized ray (2173.), and may also easily extend the investiga- 

 tion to bodies which, from their irregularity of form, imperfect 

 transparency, or actual opacity, could not be examined by a 

 polarized ray, for here we have no difficulty in the application 

 of the test to all such substances. 



2276. The property of being thus repelled and affected by 

 magnetic poles, was soon found not to be peculiar to heavy 

 glass. Borate of lead, flint-glass, and crown-glass set in the 

 same manner equatorially, and were repelled when near to 

 the poles, though not to the same degree as the heavy glass. 



2277. Amongst substances which could not be subjected to 

 the examination by light, phosphorus in the form of a cylin- 

 der presented the phsenomena very well; I think as powerfully 

 as heavy glass, if not more so. A cylinder of sulphur, and a 

 long piece of thick India rubber, neither being magnetic after 

 the ordinary fashion, were well-directed and repelled. 



2278. Crystalline bodies were equally obedient, whether 

 taken from the single or double refracting class (2237.). 

 Prisms of quartz, calcareous spar, nitre and sulphate of soda, 

 all pointed well, and were repelled. I 



2279. I then proceeded to subject a great number of bodies, 

 taken from every class, to the magnetic forces, and will, to 

 illustrate the variety in the nature of the substances, give a 

 comparatively short list of crystalline, amorphous, liquid and 

 organic bodies below. When the bodies were fluids, I in- 

 closed them in thin glass tubes. Flint-glass points equatori- 

 ally, but if the tube be of very thin glass, this effect is found 

 to be small when the tube is experimented with alone; after- 

 wards, when it is filled with liquid and examined, the effect 

 is such that there is no fear of mistaking that due to the glass 

 for that of the fluid. The 



tubes must not be closed 

 with cork, sealing-wax, or 

 any ordinary substance 

 taken at random, for these 

 are generally magnetic 

 (2285.). I have usually 



