CRYSTALS OF BISMUTH IN VARIOUS MEDIA. 
11 
a very useful and important indicator of the direction of the lines of force in a mag- 
netic field, for at the same time that it takes up a position showing their course, it 
does not by its own action tend sensibly to disturb them. 
249/ . Many of these motions are similar to, and have relation with, those described 
by Plucker, Reich, and others, as obtained by the action of iron and magnets on 
bismuth, in its simple diamagnetic condition. These results are by them and others 
considered as indicating that the bismuth, as I had originally supposed (2429, &c.), 
has really in its diamagnetic state, a magnetic condition the reverse of that of iron. 
I am not acquainted with all of them, or with the reasoning thereon (being in the 
German language) ; but such as I am aware of, and have reobtained, seem to me to 
be simple results of the law I formerly laid down (2267. 2418.), namely, that diamag- 
netic bodies tend to proceed from stronger to weaker places of magnetic force : and 
give no additional or other proof of the assumed reverse polarity of bismuth than the 
former cases of action which 1 had given, coming under that law. 
2498. Supposing that the intervening or surrounding matter might, in some 
manner, affect the magnecrystallic action of bismuth and other bodies, I fixed the 
magnetic poles at a given distance (about two inches) asunder, suspended a crystal 
of bismuth in the middle of the magnetic field, and observed its vibrations and set. 
Then, without any other change, I introduced screens of bismuth, being blocks about 
two inches square and 0'7o of an inch in thickness, between the poles and the crystal, 
but I could not perceive that any change in the phenomena was produced by their 
presence. 
2499. The bismuth crystal (2459.) was suspended in water between the magnetic 
poles of the horse-shoe magnet. It set well in accordance with the general law (2479.), 
and it took five revolutions of the torsion index at the upper end of the suspending 
silk filament to displace it, and cause it to turn into the diametral position. This is, 
as well as I could observe the results, the same amount of torsion force required to 
effect its displacement when the crystal was placed in the same position, but sur- 
rounded with air only. 
2500. The same bismuth was then suspended in a saturated solution of proto- 
sulphate of iron (adapted as a magnetic medium), it set as before with apparently no 
change of any kind ; and when the torsion force was put on, it still required five 
turns of the index, as before, to cause the displacement of the crystal, and its passage 
into the diametral position. 
2501. Whether therefore crystals of bismuth be immersed in air, or water, or solu- 
tion of sulphate of iron, or placed between thick masses of bismuth, if they be subject 
to the same magnetic force, the magnecrystallic force exerted by them is the same 
both in nature, direction and amount. 
