24 DR. FARADAY’S EXPERIMENTAL RESEARCHES IN ELECTRICITY. (SERIES XXII.) 
2556. When the crystal was made to stand between the flat- Fig. 4. 
faced poles (2463.) obliquely, as in fi^. 4, the moment the magnet 
was excited it moved, tending to stand with its length equatorial 
or its magnecrystallic axis parallel to the lines of magnetic force. 
When the N pole was removed, and the experiment repeated, the 
same effect took place, but not as strongly as before ; and when, finally, the pole S 
was brought as near to the crystal as it could be, without touching it, the same result 
occurred, and with more strength than in the last case. 
2557. In the two latter experiments, therefore, the crystal of sulphate of iron, though 
a magnetic body and strongly attracted by such a magnet as that used, actually re- 
ceded from the pole of the magnet under the infiuence of the magnecrystallic condition. 
2558. If the pole S be removed and that marked N be retained for action on 
the crystal, then the latter approaches the pole, urged by both the magnetic and 
magnecrystallic forces ; but if the crystal be revolved 90° to the left, or 180° to the 
right, round the silken axis, so as to come into the contrary or opposite position, 
then this pole repels or rather causes the removal to a distance of the crystal, just as 
the former did. The experiment requires care, and I find that conical poles are not 
good ; but Avith attention I could obtain the results with the uttnost readiness. 
2559. The sulphate of iron was then replaced by a crystalline plate (2480.) of 
bismuth, placed as before on one side of the silk suspender, and with its magnecry- 
stallic axis horizontal. Making the position the same as that which the crystal had 
in relation to the N pole in the former experiment (2556.), so that to place its axis 
parallel to the lines of magnetic force it must approach this magnetic pole, and then 
throwing the magnet into an active state, the bismuth moved accordingly, and did 
approach the pole, against its diamagnetic tendency, but under the infiuence of the 
magnecrystallic force. The effect was small but distinct. 
2560. Anticipating, for a short time, the result of the reasoning to be given further 
on (26O7.), I will describe a corresponding effect obtained with the red ferro-prussiate 
of potassa. A crystal of this salt had its acute linear angles ground away, so as to 
convert it into a plate with faces parallel to the plane of the optic axis, and was then 
made to replace the plate of bismuth. Being in the position before represented 
(2556.), and the magnet rendered active, it moved, placing the plane of the optic axes 
eqnatorially, as Plucker describes. When the pole N was removed and S brought 
up to the crystal, the same motion occurred, the crystal retreating from the pole ; 
and when S pole was removed and N brought towards the crystal, it moved as be- 
fore, the whole body now approaching towards the pole. On inclining the crystal 
the other way, i. e. making its place on the other side of the equatorial line, the S 
pole caused it to approach and the N pole to recede. So that the same pole seemed 
able either to attract or repel the same side of the crystal ; and either pole could be 
made to show this apparent attractive and repulsive force. 
2561. Hence a proof that neither attraction nor repulsion causes the set, or 
