Mr. W. Sturgeon on Electro-Magnets. 195 



by exercising them on soft iron than on hard steel, my experi- 

 ments were fimited to small masses, generally to a few inches 

 of rod iron about half an inch in diameter. Some ot those 

 pieces were employed whilst straight, and others were bent 

 into the form of a horse-shoe magnet, each piece being en- 

 compassed by a spiral conductor of copper wire*. The mag- 

 netic energies developed by these simple arrangements are 

 of a very distinguished and exalted character, as is conspicu- 

 ously manifested by the suspension of a considerable weight 

 at the poles during the period of excitation by the electric in- 

 fluence. . . • 1 T 



An unparalleled transiliency of magnetic action is also dis- 

 played in soft iron, by an instantaneous transition from a 

 state of total inactivity to that of vigorous polarity, and also 

 by a simultaneous reciprocity of polarity in the extremities ot 

 the bar;— versatilities in this branch of physics to which sott 

 iron is preeminently prone, and which by the agency of elec- 

 tricity become demonstrable with the celerity of thought, and 

 illustrated by experiments the most splendid in magnetics. _ 

 It is, moreover, abundantly manifested by ample experi- 

 ments, that galvanic electricity exercises a superlative degree 

 of excitation on the latent magnetism of soft iron, and calls 

 forth its recondite powers with astonishing promptitude, to an 

 intensity of action far surpassing anything which can be ac- 

 complished by any known application of the most vigorous 

 permanent magnet, or by any other mode of experimenting 

 hitherto discovered. It has been observed, however, by ex- 

 perimenting on different pieces selected from various sources, 

 that notwithstanding the greatest care be observed in prepar- 

 ino- them of an uniform figure and dimensions, there appears 

 a Considerable difference in the susceptibility which they in- 

 dividually possess of developing the magnetic powers ; much 

 of which depends upon the manner of treatment at the forge, 

 as well as upon the natural character of the iron itselff. _ 

 The superlative intensity of electro-magnets, and the faci- 

 lity and promptitude with which their energies can be brought 

 into play, are qualifications admirably adapted for their mtro- 

 duction into a variety of arrangements in which powerful 

 magnets so essentially operate, and perform a distinguished 



* The [)ieces of soft iron whicii were first m!i-;netizcd in this way are 

 members of an electro-magnetic apparatus, which I had the honour to pre- 

 sent to the "Society of Arts, &c." in the spring of lSii5; for which the 

 Society presented me with their large silver medal, and a purse ol tnirty 

 (guineas. . . , 



t 1 have made a nimibcr c.f experiments on small pieces, Irom the rc- 



bults of which it aiipeans that viucli /lammaing is iw^Uy detrimental to 



2 C a ^ne 



