8 DR. FARADAY’S EXPERhMENTAL RESEARCHES IN ELECTRICITY. (SERIES XXII.) 
crystals before spoken of (2459. 2468. 2476.). In this manner, also, the diamagnetic 
effect of the bismuth may be neutralized ; for it is easy to build up a prism whose 
breadth and thickness is equal, and this being- hung with the length vertical, points 
well and without any interference of diamagnetic action. 
2484. By placing three equal plates at right angles to each other, a system is ob- 
tained, which has lost all power of pointing under the influenee of the magnet, the 
force being, in every direction, neutralized. This represents the case of finely 
ciystallized or amorphous bismuth. The same result (having the same nature) may 
be obtained by taking a selected uniform mass of crystals (2457.)? melting it in a 
glass tube and resolidifying it ; unless the crystallization is large and distinct, which 
rarely happens, the piece obtained is apparently without magnecrystallic force. A 
like result is also obtained by breaking up the crystal and putting the small frag- 
ments or powder into a tube, and submitting the whole to tlie force of the magnet. 
2485. These experiments on bismuth are not difficult of repetition ; for, except 
those which require the sudden production or cessation of the magnetic force, the 
whole may be repeated with an ordinary horse-shoe magnet. A magnet, with which 
I have wrought considerably, consists of seven bars placed side by side, and being 
fixed in a box with the poles upwards, presents two magnet cheeks, an inch and a 
quarter apart, between which is the magnetic field, having the lines of force in a 
horizontal direction. The poles of the magnet should be covered, each with paper, 
to prevent communication of particles of iron or rust. The best place for the piece 
of bismuth is, of course, between the poles; not level however with their tops, but 
from 0'4 to TO inch lower down (2463.), that the effect of flat-faced poles may be 
obtained. If it be desired to strengthen the lines of magnetic force, this may be done 
by introducing a piece of iron between the poles of the magnet, and so, by virtually 
causing them to approach, lessen the width of the magnetic field between them, 
2486. The magnet I used would sustain 30 lbs. at the keeper ; but employing 
small pieces of bismuth, I have easily obtained the effects with magnets weighing 
themselves not more than 7 ounces, and able to sustain only 22 ounces ; so that the 
experiments are within the reach of every one. 
2487. Whilst the crystal of bismuth is in the magnetic field, it is affected very di- 
stinctly, and even strongly, by the near approximation of soft iron or magnets, and 
after the following manner. Let fig. 1 represent in plan the Fig- T 
position of the two chief magnetic poles, and of a piece of 
crystallized bismuth between them, which, by its magne- 
crystallic condition, points axially. Then, if a piece of soft 
iron be applied against the cheek of the pole, as at e, and 
also near to the bismuth, as at a, it will affect the latter and 
