^O MAGNETISM. 



II. 



Experiments on the Magneiifni of jlender Iron Wires. 



Bj/ JOHH GOUGH, Efq, 



To Mr. NICHOLSON. 



SIR, Middkjhaiv, January 9, 1805. 



A general maxim JL HE general phenomena of magnetifm have given rife to a 

 ftatedf"^ ' "^ maxim which fliall be here flated in the words of a judicious 

 writer on the fubjed. *' The magnetifm acquired by being 

 placed within the influence or the fphere of activity of a 

 magnet in foft iron, lafts only while the iron continues in that 

 filuation ; and when removed from the vicinity of the magnet, 

 its magnetifm vaniflies immediately ; but with hard iron, and 

 efpeciah'y with fleel, the cafe is quite different ; for the harder 

 the iron or fteel is, the more permanent is the magnetifm, 

 wliich it acquires from the influence of a magnet." Cavallo on 

 Magnetifm, London, 1787, p. 30. 

 llem^jrkson this ; This propofition is of great utility in the fcience, for it explains 

 """""■ a variety ofrelations betwixt the magnet and ferruginous bodies, 



but I have obferved one phenomenon that appears inexplica- 

 ble on the principle, and confequently may be faid to offer 

 one exception to the general propofition. As my experiments 

 on the fubjefl are very eafy, it feems advifeable to deliver 

 the leading circumftances in the form of fo many precepts 

 becaufe this method will affift any one defirous of purfuing 

 the enquiry, to repeat them with eafe. 

 An experiment Experiment 1. Apply either pole of a flrong magnet to one 

 he maxim. ^"^ ^^ ^ "^^^^ horizontal bar ot clean loft iron, and a particle 

 of iron equally foft to the other end. This particle will 

 remain fufpended at the extremity of the bar until the magnet 

 is withdrawn ; but the removal of this power will diffolve the 

 oonneclion fubfifling betwixt the two pieces of iron, and the 

 particle will drop off immediately. 

 An experiment Exp. 2. The preceding experiment confirms the maxim 

 the m'axim"^ ftated above, when conduced according to the foregoing 

 diredions ; but let it be repeated with the following alteration, 

 and it will contradidl the general propofition. In place of the 

 particle of foft iron, fubftitute a piece of iron wire of number 

 32 in the wire drawers fcale, the weight of which may 

 amount to two or three grains. The removal of the magnet 



will 



