1822.] of Magnetism to Iron in different Positions. Sjj 



magnetism. It app6ars from Mr. Scoresby's experiments, th^ 

 there are various modes by which this effect may be accelerated^ 

 such as torsion, bending, filing, scowering, &c. I have founa 

 that a piece of iron may be placed near the poles of a magnet,' 

 ^nd remain for some time, without receiving any magnetism , 

 but if, while in this position, any of the above operations b6f 

 performed on it, it immediately becomes magnetic. I have alsOr 

 found that if a piece of iron wire be bent or twisted into any 

 figure, and in this state be magnetized, and then bent back inta 

 an opposite direction, or even simply straitened, its magnetism 

 is either wholly, or very nearly, destroyed. The same thing also 

 occurs if the wire be magnetized when straight, and then bent/ 

 Hence I think we may infer, that an intestine friction of thfe' 

 particles of iron makes it capable of imbibing magnetism ; and* 

 a similar friction in an opposite direction made after the former 

 produces a contrary effect. What connexion these facts may 

 have with M. Ampere's idea of the spiral currents may be ati 

 interesting subject of investigation. At present I will conclude 

 by remarking, that the apparatus used by Mr. Scoresby in his 

 experiments appears, from the description, to be well adapted 

 for experiments of the kind I have described. I, therefore, con- 

 ceive it not improbable that my ideas may have occurred to him 

 also ; but till any more accurate examination of them is mad4 

 pujplic, I think the present memoir may not be unacceptable to 

 those who are interested in the improvement of this branch of 

 science, which, owing in a great measure to the labours of Mr. 

 Barlow and Professor Hansteen, and the universal interest in it 

 excited of late, both in a theoretical and practical point of view, 

 seems to be advancing with unexampled rapidity ; and to pro-i- 

 mise a rich harvest of discovery, both in application to practical 

 purposes, and in opening new connexions with other depart- 

 ments of science. I am. Sir, yours, &c. 



Baden Powell* 



I 



Article V. 



On the Separation of Iron from other Metals, 

 By J. F. W. Herschel, Esq. FRS.* 



An easy and exact method of separating iron from the other 

 metals with which it may happen to be mixed, has always been 

 a desideratum in chemistry. Every one conversant with the 

 analysis of minerals is aware of the difficulty of the problem^ 

 which indeed is such that, in experiments conducted on any thing , 



* From the Philosophical Transactions, for 1821, Part II. 



