Bodies are repelled from the Poles of a Magnet. "** 159 



and even on the question whether it is magnetic, hke iron, or 

 diamagnetic, Uke bismuth, differences of opinion appear to 

 prevail. Such differences are to be referred to the extreme 

 feebleness of the force proper to the wood itself, and its con- 

 sequent liability to be masked by extraneous impurity. In 

 handling the substance intended for experiment the fingers must 

 be kept perfectly clean, and frequent washing is absolutely 

 necessary. After reducing the substance to a regular shape, so 

 as to annul the influence of exterior form, its outer surface must 

 be carefully removed by glass, and the body afterwards sus- 

 pended by a very fine fibre between the poles of a strong electro- 

 magnet. 



The first step in the present inquiry was to ascertain whether 

 the substance examined was paramagnetic* or diamagnetic. 

 It is well known, that, in experiments of this kind, moveable 

 masses of soft iron are placed upon the ends of the electro- 

 magnet, the distance between the masses being varied to suit 

 the experiment. In front of a pointed mass of iron of this kind, 

 a cube of wood was suspended, and if, on exciting the magnet, 

 the cube was repelled by the point, it was regarded as diamag- 

 netic; if attracted, it was con- 

 sidered to be paramagnetic. The Fig- !■ 

 force was considerably intensified 

 by placing the two moveable 

 poles as in fig. 1, and suspending / 

 the cube at a on the same level / 

 with the points; a diamagnetic 

 body placed there is, on the de- 

 velopment of the magnetic force, 

 forcibly driven from the line 



which unites the points, while a magnetic body is forcibly drawn 

 in between them. 



Having thus observed the deportment of the mass, the cube 

 was next suspended between the flat ends of the poles sketched 

 in fig. 1. The parallel faces were about three-quarters of an 

 inch apart, and in each case the fibre of the suspended wood 

 was horizontal. The specimen first examined was Beef- wood : 

 suspended in the position a, fig. 1, the mass was repelled : sus- 

 pended between the flat poles, on exciting the magnet, the cube, 

 if in an oblique position, turned and set its fibre equatorial. 



* The effects exhibited by iron and by bismuth come properly under 

 the general designation of mar/netic pluenomena : to render their subdivision 

 more distinct Mr. Faraday has recently introduced the word paramagnetio 

 to denote the old magnetic effects, of which the action of iron is an example. 

 Wherever the word magnetic occurs, without the prefix, it is always the 

 old action that is referred to. 



