34 DR. FARADAY’S EXPERIMENTAL RESEARCHES IN ELECTRICITY. (SERIES XX.) 
then have been considered as a peculiar and isolated effect, was the consequence of 
a general property, which is now shown to belong to all matter*. 
2309. I now turn to the consideration of some peculiar phenomena which are pre- 
sented by copper and several of the metals when they are subjected to the action of 
magnetic forces, and which so tend to mask effects of the kind already described, that 
if not known to the inquirer they would lead to much confusion and doubt. These 
I will first describe as to their appearances, and then proceed to consider their origin. 
2310. If instead of a bar of bismuth (2296.) a bar of copper of the same size be 
suspended between the poles (2247.)> and magnetic power be developed whilst the 
bar is in a position oblique to the axial and equatorial lines, the experimenter will 
perceive the bar to be affected, but this will not be manifest by any tendency of the 
bar to go to the equatorial line; on the contrary, it will advance towards the axial 
position as if it were magnetic. It will not, however, continue its course until in 
that position, but, unlike any effect produced by magnetism, will stop short, and 
making no vibration beyond or about a given point, will remain there coming at 
once to a dead rest : and this it will do even though the bar by the effect of torsion 
or momentum was previously moving with a force that would have caused it to make 
several gyrations. This effect is in striking contrast with that which occurs when 
antimony, bismuth, heavy glass, or other such bodies are employed, and it is equally 
removed from an ordinary magnetic effect. 
2311. The position which the bar has taken up it retains with a considerable de- 
gree of tenacity, provided the magnetic force be continued. If pushed out of it, it 
does not return into it, but takes up its new position in the same manner, and holds 
it with the same stiffness ; a push however, which would make the bar spin round 
several times if no magnetism were present, will now not move it through more than 
20° or 30°. This is not the case with bismuth or heavy glass ; they vibrate freely in 
the magnetic field, and always return to the equatorial position. 
2312. The position taken up by the bar may be any position. The bar is moved 
a little at the instant of superinducing the magnetism, but allowing and providing 
for that, it may be finally fixed in any position required. Even when swinging with 
considerable power by torsion or momentum, it may be caught and retained in any 
place the experimenter wishes. 
2313. There are two positions in which the bar may be placed at the beginning of 
* M. de la Rive has this day referred me to the Bibliotheque Universelle for 1829, tome xl. p. 82, where 
it will he found that the experiment spoken of above is due to M. la Bajllif of Paris. M. la Baillif showed 
sixteen years ago that both bismuth and antimony repelled the magnetic needle. It is astonishing that such an 
experiment has remained so long without further results. I rejoice that I am able to insert this reference before 
the present series of these researches goes to press. Those who read my papers will see here, as on many other 
occasions, the results of a memory which becomes continually weaker ; I only hope that they will be excused, 
and that omissions and errors of that nature will be considered as involuntary. — M. F. December 30, 1845. 
