348 M. Elias on a simple Method of Magnetizing Steel Bars. 



after the able experiments and inferences of Dr. Faradaj' and 

 Mr. Armstrong, I should attribute the electricity to the fric- 

 tion of the water against the sides of the boiler, caused by 

 rapid currents of steam passing from the bottom, aided by im- 

 mense pressure and heat. If it were the steam carrying water, 

 surely the greatest electrical force should be at the exit, and 

 not at the sides ; the steam may be a carrier and give shock. 

 To show the conducting power of steam, at- 

 tach a pith-ball by a silk thread and wax to 

 an excited glass tube. On bringing this 

 near a lighted candle the electricity is dissi- 

 pated. The celebrated philosopher, M. 

 Arago, states that this is occasioned by the 

 conical blaze, whereas it arises from the va- 

 pour of the candle. 



In my next communication to your valuable Journal I shall 

 make known some perfectly new, and I hope interesting, ex- 

 periments on the pyro-electricity of the glass cover of tlie bi- 

 nacle compass produced by the solar rays, giving a new view 

 of that deflection of the needle which was attributed to local 

 attraction. Humanity makes this a subject of great interest, 

 and therefore 1 shall give the experiments much attention. 



LIX. Description of a Simple Method of Magnetizing Steel 



Bars. By P. Elias of Haarlem^. 

 \ T the present day, when the possession of powerful steel 

 ■^^ magnets must be desirable to experimentalists, it will 

 perhaps not be without interest to many to become acquainted 

 with the method by which the smallest needle as well as the 

 heaviest steel bar can be instantly magnetized to saturation 

 with the greatest facility. 



The method hitherto employed is that of the double passing, 

 discovered by Knight and improved by Duhameland Mitchell. 

 Several persons have proposed the employment of electro- 

 magnets for this purpose, others suspending the steel bar to be 

 magnetized at a red heat to the pole of an electro-magnet, and 

 allowing it to cool in that position. The first method is in- 

 convenient, as it is not possible to move electro-magnets about 

 so freely as steel magnets ; the latter, as every one knows, is 

 without effect ; consequently the old method has been retained. 

 This however has the inconvenience, that in the first place it 

 is necessary to be well acquainted with the manipulation of 

 magnetizing; and secondly, that you must already possess that 



* From Poggendorff's Annalen, vol. Ixii. p. 249 j communicated by W. 

 Francis, Ph.D. 



