10 DR. FARADAY’S EXPERIMENTAL RESEARCHES IN ELECTRICITY. (SERIES XXII.) 
passing through the bismuth. The same results were obtained with the crystal 
(2487.) under similar circumstances, and corresponding results were obtained when 
the soft iron rod was applied betvveen the S cheek of the magnet and the bismuth. 
The like effects were also obtained with plates of arsenic and antimony. 
2491. When a magnet is used instead of soft iron, corresponding effects are pro- 
duced ; only, it must be remembered, that if the chief magnet be very powerful, it 
may often neutralize, and even change, the magnetism of the small approximated 
magnet ; and this can happen with the latter (as to external influence) whilst 
in the magnetic field, even though when withdrawn it may appear to remain un- 
altered. 
2492. Thus, when the plate of bismuth was suspenfled between the cheeks of the 
horse-shoe magnet (2485.), fig. 2, and the north pole of a small magnet (the blade of 
a pocket-knife) was placed at a or 6, it caused recession of the part of the bismuth 
near it, and precisely for the same reasons as those that existed when the soft iron 
was there. When the extra pole was placed at c or d, the action was more feeble 
than in the former case, and consisted in 'an approximation of that part of the bismuth 
to the pole. As this position of the subordinate pole would terminate and neutralize 
certain of the lines of magnetic force proceeding from the south pole of the horse-shoe 
magnet, so the resultant of the lines of force passing through the bismuth would be 
changed in direction, being rendered oblique to their former course, and precisely 
in the manner represented by the motion of the bismuth, in its tendency to place its 
line of force parallel with them in their new position. 
2493. An approximated south pole caused motions in the contrary direction. 
2494. When the subordinate pole was applied to the edge of the plate, the little 
magnet being in the equatorial position (fig. 3), then instead of being neutral, as the 
iron was, it caused the plate to move in a tangential direction, either to the right or 
the left, according as it was either a south or a north pole, just indeed as the iron did 
when, by inclining it, the approximated end became a pole (2490.). This effect was 
shown in a still more striking degree by using the crystal of bismuth (2487-), because, 
from its form and position the magnetic curves most affected by the extra pole were 
more included in the bismuth than when the plate was used. 
2495. Innumerable variations of these motions may be caused, and appearances 
of attraction or repulsion, or tangential action be obtained at pleasure by the use of 
crystals having the magnecrystallic axis corresponding with their length, or plates 
where it accords with their thickness ; and either permanent or temporary subsidiary 
magnetic poles. By making the moveable pole travel slowly round the bismuth 
from the neutral point m to the other neutral point 7i, fig. 3, a summary of the whole 
can be obtained, and it is found that they all resolve themselves into the general 
law before expressed (2479.) : the magnecrystallic axis and the resultant of magnetic 
force passing through the bismuth, tending to become parallel. 
2496. Hence a small crystal or plate of bismuth (or arsenic (2532.)) may become 
