1881.] 



Molecular Magnetism. 



221 



the experiments upon the same wire. If these experiments are 

 repeated upon an iron wire, the effects are far greater in the first 

 instance, so great that they were thrown out of the range of my 

 measurements ; it was only after a few seconds of successive reversals 

 that the zero of the wire was brought within range, and although these 

 rapidly decreased, exactly similar effects were observed as in the steel. 

 And as with all moderate ranges, I could bring the iron at once to a 

 complete zero by torsion, and as torsion alone would produce this com- 

 plete zero, I believe we have here effects from causes identical with 

 those related in the first chapter. 



Having noticed in my previous papers the increased molecular 

 activity caused by the approach of a powerful permanent magnet, 

 and believing that the permanent spirality above mentioned was due 

 to this alone, and not to an increased polarity, I magnetised strongly 

 an iron wire giving as usual a reversed spiral for different currents of 

 but 10°. I now heated the wire by a spirit flame to a dull red heat, 

 whilst the current was passing through it, and on cooling I found 

 a similar but stronger permanent torsion of 250° ; both currents, 

 as in the previous experiments, having a right-handed spiral. 

 Thus a current of electricity passing through a wire nearly red hot 

 determines a molecular arrangement, or path, which on cooling forces 

 currents of either direction to follow the path which had been deter- 

 mined under the influence of heat. 



3. Molecular Sounds. 



The passage of an intermittent current though iron or other wire 

 gives rise to sounds of a very peculiar and characteristic nature. Page, 

 in 1837, first noticed these sounds on the magnetisation of wires in a 

 coil. De la Rive published a chapter in his " Treatise on Electricity " 

 (1853) on this subject, and he proved that not only were sounds 

 produced by the magnetisation of an iron wire in an inducing coil, 

 but that sounds were equally obtained by the passage direct of the 

 current through the wire. Gassiot, 1844, and Du. Moncel, 1878-81, 

 have both maintained the molecular character of these sounds. Beis 

 made use of them in his, the first electric telephone invented, and 

 these sounds, since the apparition of Bell's telephone, have been often 

 brought forward as embodying a new form of telephone. These 

 sounds, however, for a feeble source of electricity, are far too weak for 

 any applied purposes, but they are most useful and interesting where 

 we wish to observe the molecular action which takes place in a 

 conducting wire. I have thus made use of these sounds as an inde- 

 pendent method of research, and by their means verify any point 

 left doubtful by other methods, some of which I have already de- 

 scribed. 



The apparatus was the same as that described in the last section, 



