1881.] 



Molecular Magnetism. 



219 



travels in spirals around a longitudinal magnet, and that the direction 

 of this spiral is entirely due to which pole of an electric current enters 

 the north or south pole. I propose soon, however, to show that under 

 certain conditions these effects are entirely reversed. 



If through this magnetised wire I pass a constant current of two 

 bichromate cells, and at the same time an intermittent one, the spiral 

 is increased to 15°, but the direction of the intermittent current 

 entirely depends on that of the constant current. Thus, if the positive 

 of the constant current enters the north pole, the intermittent positive 

 slightly increases the spiral to 17°, and the negative to 13°, both 

 being right-handed ; the two zeros of the constant battery are, how- 

 ever, as we might expect from the preceding experiment, on opposite 

 sides of and at equal distances from the true zero ; but if we 

 magnetise the wire whilst a constant current is passing through it, a 

 very great molecular disturbance takes place ; loud sounds are heard 

 in the telephone, and it requires for each current a movement of the 

 coil of 40°, or a total for the two currents of 80°. This, however, is 

 not the only change that has taken place, as we now find that both 

 constant currents have* a right-handed spiral; the positive under 

 which it was magnetised, a right-handed spiral of 95° ; the negative, 

 a right- handed spiral of 15°, and the true central or zero point of the 

 true currents indicates a permanent spiral of: 55°. 



This wire was magnetised in the usual way, by drawing the 

 north pole of my magnet from the centre to one extremity, the south 

 from the centre to the other, and this was repeated until its maxi- 

 mum effects were obtained. In this state I found, sliding the coil 

 at different portions, that the spiral currents Were equal, and in the 

 same direction throughout. 



It now occurred to me to try the effect of using a single pole of 

 the magnet ; this was done whilst a constant current was passing 

 through the wire, commencing at the extremity where the positive 

 joined, drawing the north pole through the length of the wire, from 

 positive towards the negative ; the effect was most remarkable, as the 

 steel wire now gave out as loud tones as a piece of iron, and the 

 degree on the coil showed 200°. The constant and intermittent 

 currents now showed for either polarity a remarkably strong right- 

 handed twist; the positive 200 right, and the negative 150 right- 

 handed spirals. The molecular strain on the wire from the reaction of 

 the electric current upon the molecular magnetism was so great, that 

 no perfect zero would be obtained at any point, a fact already observed 

 when a wire was under an intense strain, producing tertiary currents 

 that superposed themselves upon the secondary. In order to compare 

 these spiral currents with those obtained from a known helix, I found 

 that taking a copper wire of similar diameter (0*5 millim.), and 

 winding it closely upon the steel wire ten turns to each centimetre, 



