Intelligence and Miscellaneous Articles. 555 
The specimen which gave me the most marked effects, is a small 
prism of 21°55 millims. in length by 12°55 millims. in breadth, 
weighing 16°94 grs.: its density is 6°25. I had a great deal of 
trouble in cutting it, in consequence of the slight mutual adherence 
of the lamelle. I found that the action of the magnet upon this 
material was stronger when the cleavages were vertical than when 
they were horizontal. Before annealing, the relation of the forces 
which caused the bar to oscillate was as 1 : 1°16. After annealing, 
this relation was notably weaker: it was no more than 1 : 1°09. 
These numbers are the averages of several determinations made 
with the large magnet at a distance of 24 centimetres. With a 
small straight magnet placed at a distance of 2 centimetres only, 
this relation was always stronger. It was found to be 1: 1°21 
before, and 1 : 1:12 after annealing. 
Another prism produced by the reduction of a compact mineral 
fragment, and aiso compressed, but in which the lamellated structure 
was not apparent, furnished differences of the same nature as the 
preceding, but very slight. 
I also operated upon a specimen in which the iron was inter- 
mixed with lamelle of copper. In consequence of the slight aggre- 
gation of the material, I was compelled, to enable me to work it, to 
render the contact of the particles more intimate, by heating it to a 
high temperature, and submitting it in this state to a powerful 
pressure. In this way I prepared two pieces: the first was heated 
to a welding white heat, when the copper was fused. Its density 
is 7°27. I found no difference in the duration of its oscillations, 
according as the stratification was vertical or horizontal. The second 
piece was only brought to a very bright cherry-red heat. Its density 
is only 6°20; so that the approximation was less intimate than in 
the preceding case. ‘here is also a considerable difference ; the 
relation of the forces in the two cases being as 1 : 1°047. 
It is important to observe, that, at least in accordance with what 
is generally admitted, these results are independent of tie influence 
of the currents induced in the body which oscillates above the mag- 
net. In fact, the fundamental character of the phenomenon dis- 
covered by Arago, of which induction furnishes the explanation, is 
the rapid diminution of the oscillations, without any sensible altera- 
tion of their duration. 
It is also remarkable that the arrangement of the cleavages which, 
in our experiment, developes a more powerful magnetism, is also that 
which, if we pay attention only to the possible currents of induction 
in the moveable mass, would give greater energy to these currents. 
Lastly, to draw the last and most important consequence from the 
fact to which I have just referred, we must observe that this influ- 
ence of the arrangement of the molecules must be intimately con- 
nected with magnetism or diamagnetism itself. We find it, in fact, 
equally sensible with bismuth and iron, although the diamagnetism of 
the former is about 25,000 times weaker than the magnetism of the 
latter. We also find that the same circumstance, namely, the ver- 
tical position of the cleavages, which increases the diamagnetism of 
‘bismuth, also increases the magnetism of iron.—Comptes Rendus, 
October 5, 1857, p. 477. 
