1903.] 



Some Experiments in Magnetism. 



9 



this way, and quickly, artificial lodestones of some strength, for the 

 products of the (a) experiments were able to pick up small pieces of 

 soft iron. 



Thinking that in these cases part, at any rate, of the polarity might 

 be due to particles of the levigated iron which had escaped combination 

 with either the sulphur or the oxygen, the writer next attempted to 

 make a magnet out of the particles of levigated iron themselves. 

 This was done by half filling a small test tube with solid paraffin, 

 melting it, loosely corking the tube, and placing it in a horizontal 

 position until the paraffin had solidified. The remaining air space, of 

 semicircular section, was then filled with the levigated iron, the tube 

 again corked, and placed horizontally through the bored poles of the 

 electro-magnet ; the current was switched on, and whilst the tube was 

 in position, with the iron uppermost in the tube, the paraffin below it 

 was melted by cautiously heating it with a Bunsen. As the paraffin 

 melted, the tube being gently tapped meanwhile, the iron particles 

 were for the time capable of small movements, arranging themselves 

 along the lines of force. The paraffin was then allowed to solidify 

 and grow cool, the current being maintained the while, the tube 

 removed and the glass gently peeled off, by first cutting it round 

 with a diamond, leaving a bar of soft iron particles embedded in 

 paraffin, which was a magnet, and has remained so ever since, without 

 showing any signs of losing its magnetism, and sufficiently strong to 

 develop tufts at either pole when dipped into a heap of the levigated 

 iron. 



As it still seemed possible that the permanent polarity of this magnet 

 might be due to carbon in it, which it certainly contained, though in 

 very small quantity, it seemed well to try a similar experiment with 

 particles of pure electrolytic iron, and to try it with molecules of the 

 iron instead of assemblages of molecules, already under the influence of 

 forces opposing the development of the magnetic polarity, and these 

 considerations at once suggested that the iron should be deposited 

 electrolytically from the solution of one of its compounds in a powerful 

 magnetic field on some " non-magnetic " substance, such as platinum. 

 The photograph shows the arrangement actually used, and, which it 

 may be stated at once, proved entirely successful. 



The apparatus consisted of the electro-magnet, with two special 

 pole pieces, designed to concentrate the magnetic lines of force into 

 a space of length, the distance between them ; of height, the height 

 of the pole pieces as shown, and of thickness one-eighth of an 

 inch. The poles thus tapered to what may be called a blunt 

 vertical line. Between the poles is the glass cell, in the centre 

 of which hangs the strip of platinum foil, previously proved to 

 have no visible effect upon a magnet, so that its plane is in the para- 

 magnetic position, the platinum approaching close to the sides of the 



