C 147] 

 XXVIII. Proceedings of Learned Societies. 



ROYAL SOCIETY. 



EXPERIMENTAL Researches in Electricity." By Michael 

 Faraday, Esq., D.C.L., F.R.S. &c. Twentieth Series. Sec- 

 tion 26th. " On New Magnetic Actions ; and on the Magnetic 

 Condition of all Matter." 



The following is the order in which the several divisions of the 

 subject treated of in this section of the author's researches in elec- 

 tricity succeed one another: — 1. Apparatus required. 2. Action 

 of magnets on heavy glass. 3. Action of magnets on other sub- 

 stances acting magnetically on light. 4-. Action of magnets on the 

 metals generally. 5. Action of magnets on the magnetic metals and 

 their compounds. 6. Action of magnets on air and gases. 7. Ge- 

 neral considerations. 



In giving an account of the contents of this paper, any attempt to 

 follow the track of the author in the precise order in which he re- 

 lates the consecutive steps of his progress in this new path of dis- 

 covery, would fail of accomplishing its object : for, by adhering to 

 such a course, it would scarcely be possible to comprise within the 

 requisite limits of an abstract the substance of a memoir extending, 

 as the present one does, to so great a length, and of which so large 

 a portion is occupied with minute and circumstantial details of ex- 

 periments ; or to succeed in conveying any clear and distinct idea of 

 the extraordinary law of nature brought to light by the author, and 

 of the important conclusions which he has deduced. 



One of the simplest forms of experiment in which the operation 

 of this newly-discovered law of magnetic action is manifested, is the 

 following: — A bar of glass, composed of silicated borate of lead, 

 two inches in length, and half an inch in width and in thickness, is 

 suspended at its centre by a long thread, formed of several fibres of 

 silk cocoon, so as to turn freely, by the slightest force, in a hori- 

 zontal plane, and is secured from the agitation of currents of air by 

 being enclosed in a glass jar. The two poles of a powerful electro- 

 magnet are placed 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 position of the bar be such that its axis is in- 

 clined at half a right angle to that line, then, on completing the 

 circuit of the battery so as to bring the magnetic power into opera- 

 tion, the bar will turn so as to take a position 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 pheno- 

 menon, but in a still more marked manner. It is well known that a 

 bar of iron, placed in the same circumstances, takes a position co- 

 incident with the direction of the magnetic forces ; and therefore at 

 right angles with the position taken by the bar of bismuth subjected 

 to the same influence. These two directions are termed by the au- 

 thor axial and equatorial; the former being that taken by the iron, 

 the latter that taken by the bismuth. 



