422 Scientific Intelligence. 
One of the simplest forms of experiment in which the operation of 
this newly discovered law of magnetic action is manifested, is the fol- 
lowing :—A bar of glass, composed of silicated borate of lead, two 
inches in length and half an inch in width and in thickness, is suspend- 
ed at its centre by a long thread, formed of several fibres of silk-co- 
coon, so as to turn freely, by the slightest force, in a horizontal plane, 
and is secured from the agitation of currents of air by being enclosed 
ina glass jar. The two poles of a powerful electro-magnet are pla- 
ced one on each side of the glass bar, so that the centre of the bar 
shall be in the line connecting the poles, which is the line of magnetic 
force. If, previous to the establishment of the magnetic action, the po- 
sition of the bar be such that its axis is inclined at half a right angle to 
that line, then, on completing the circuit of the battery so as to bring 
the magnetic power into operation, the bar will turn so as to take a po- 
sition at right angles to the same line ; and, if disturbed, will return to 
that position. A bar of bismuth, substituted for the glass bar, exhibits 
the same phenomenon, bit in a still more marked manner. It is well 
known that a bar of iron; placed in the same circumstances, takes a po- 
sition coincident with the direction of the magnetic forces; and there- 
fore at right angles with the position taken by the bar of bismuth. sub- 
jected to the same influence. These two directions are termed by the 
author azial and equatorial; the former being that taken by the iron, 
the latter that taken by the bismuth. : 
Thus it appears that different bodies are acted upon by the magnetic 
forces in two different and opposite modes; and they may accordingly 
be arranged in two classes: the one, of which iron is the type, consti- 
tuting those usually denominated magnetics ; the other, of which bis- 
muth may be taken as the type, obeying a contrary law, and therefore 
coming under the generic appellation of diamagnetics. The author 
has examined a vast variety of substances, both simple and compound, 
and in-a solid, liquid, or gaseous form, with a view to ascertain their 
respective places and relative order with reference to this classification. 
e number of simple bodies which belong to the class of magnetics 
is extremely limited, consisting only of iron, which possesses the mag- 
netic property in an eminent degree, nickel, cobalt, manganese, chro- 
mium, cerium, titanium, palladium, platinum and osmium. All other 
bodies, when either solid or liquid, are diamagnetic ; that is, obey the 
same law, with regard to magnetic action, as bismuth, but with various 
degrees of intensity: arsenic is one of those that give the feeblest in- 
dications of possessing this property. The following exhibit it in in- 
creasing degrees, according to the order in which they are here enu- 
merated ; namely, ether, alcohol, gold, water, mercury, flint glass, tin, 
lead, zinc, antimony, phosphorus, bismuth. On the other hand, no gas- 
