163 



Article V. 



On the Connexion of Diamagnetism with Magnetism and 

 Electricity. By M. W. Weber. 



[From PoggendorfF's Annalen, vol. Ixxxvii. p. 145.] 

 Extracted from the Memoirs of the Royal Society of Sciences of Saxony, 

 p. 483 to 578 ; also in a separate work, " Memoirs on Electro-dynamic 

 Measurements,*' by M. Weber. Leipzig : Wiedemann, 1852. 



I. Theory, 



IN treating of magnetism, a distinction is made between per- 

 manent and variable magnets ; we regard, for example, a magnet 

 of hard steel as a permanent magnet, and a magnet of soft iron 

 as a variable one. Were the antithesis between both classes 

 perfect (which, however, is as little the case as that between 

 conductors and insulators in electricity), the magnetism of the 

 permanent magnet could only be investigated through its effects, 

 while that of the variable magnet might be investigated through 

 its causes as well as through its effects. At all events, even 

 though the antithesis be not perfect, the variable magnet is 

 more favourable to a complete examination of the nature of 

 magnetism than the permanent one. 



In the same manner, in treating of diamagnetism, it might be 

 attempted to classify diamagnets under the two heads permanent 

 and variable ; but then we should have no mark by which a per- 

 manent magnet could be distinguished from a permanent dia- 

 magnet, and thus the classification would lose all practical 

 significance. In the investigation of diamagnetism, therefore, 

 variable diamagnets only are to be considered, which permit of 

 examination partly through their causes and partly through 

 their effects. 



Now it is known that the investigation of the magnetism of a 

 magnet through its effects (produced on other bodies) leads us to 

 the knowledge of the ideal distribution of the magnetic fluid on the 

 surface of a magnet, regarding which Gauss has proved, that as 

 far as the explanation of phaenomena is concerned, it answers 



