Dec. 184-5.] Action of Magnets on Diamagnetic Bodies. 405 



difficult to perceive that comparatively large masses would 

 point as readily as small ones, because in larger masses more 

 lines of magnetic force would bear in their action on the body, 

 and this was proved to be the case. Neither was it long be- 

 fore it evidently appeared that the form of a plate or a ring 

 was quite as good as that of a cylinder or a prism ; and in 

 practice it was found that plates and flat rings of wood, sper- 

 maceti, sulphur, &c, if suspended in the right direction, took 

 up the equatorial position very well. If a plate or ring of 

 heavy glass could be floated in water, so as to be free to move 

 in every direction, and were in that condition subject to mag- 

 netic forces diminishing in intensity, it would immediately set 

 itself equatorially, and if its centre coincided with the^axis of 

 magnetic power, would remain there ; but if its centre were 

 out of this line, it would then, perhaps, gradually pass off' 

 from this axis in the plane of the equator, and go out from 

 between the poles. 



2283. I do not find that division of the substance has any 

 distinct influence on the effects. A piece of Iceland spar was 

 observed, as to the degree of force with which it set equa- 

 torially ; it was then broken into six or eight fragments, put 

 into a glass tube and tried again ; as well as I could ascertain, 

 the effect was the same. By a second operation, the calca- 

 reous spar was reduced into coarse particles ; afterwards to a 

 coarse powder, and ultimately to a fine powder: being exa- 

 mined as to the equatorial set each time, I could perceive no 

 difference in the effect, until the very last, when I thought 

 there might be a slight diminution of the tendency, but if so, 

 it was almost insensible. I made the same experiment on si- 

 lica with the same result, of no diminution of power. In re- 

 ference to this point I may observe, that starch and other bo- 

 dies in fine powder exhibited the effect very well. 



2284-. It would require very nice experiments and great 

 care to ascertain the specific degree of this power of magnetic 

 action possessed by different bodies, and I have made very 

 little progress in that part of the subject. Heavy glass stands 

 above flint-glass, and the latter above plate-glass. Water is 

 beneath all these, and I think alcohol is below water, and 

 aether below alcohol. The borate of lead is I think as high 

 as heavy glass, if not above it, and phosphorus is probably at 

 the head of all the substances just named. I verified the 

 equatorial set of phosphorus between the poles of a common 

 magnet (2273.). 



2285. I was much impressed by the fact that blood was 

 not magnetic (2280.), nor any of the specimens tried of red 

 muscular fibre of beef or mutton. This was the more striking, 



