produced by Magnetization. 459 



ways, which, however, may be reduced to three essentially di- 

 stinct. It may be supposed — 



1. That two magnetic fluids exist, which are capable of being 

 set in motion independently of the ponderable body in which they 

 reside. 



2. That two magnetic fluids exist, which can only be set in 

 motion in conjunction with the molecules of the ponderable bodies 

 in which they reside, or that there are molecular streams of a 

 permanent character rotating with the molecules, and formed by 

 the two electric fluids. 



3. That there are two electric fluids, which may be set in 

 unresisted motion in certain paths, about the stationary molecules 

 of the ponderable body. 



Of these three hypotheses, Weber felt himself compelled 

 to regard the last as the correct one, in order to bring the 

 fundamental phenomenon of the origin of diamagnetism into 

 agreement with that of the origin of magnetism ; he remarked, 

 however, in the course of his work, that as far as magnetism 

 itself is concerned, experience is in favour of the hypothesis of 

 rotatory molecules*. According to this latter hypothesis, the 

 amount of magnetism which can be induced in a body has a 

 limit when the axes of all the molecular magnets of which it is 

 composed have become parallel ; whereas the existence of such 

 a limit is incompatible with the hypothesis of the presence of 

 an inexhaustible store of a separable neutral magnetic (or electric) 

 fluid. Even, indeed, when the quantity of this fluid is not re- 

 garded as inexhaustible, still, according to the latter hypothesis, 

 the ratio between the amount m of the magnetism induced, 

 and the magnetizing power ja, must remain constant until the 

 whole of the neutral magnetism contained in the molecules of 

 the body is separated ; while, according to the other hypothesis, 

 that ratio must be a variable quantity, continually diminishing 

 according to some fixed law. 



m 



Lenz and Jacobif in their researches found this ratio, — , 



V 

 constant. Joule \ has confirmed this view. J. Miiller§, on the 

 contrary, found the ratio in question variable according to a 

 fixed law. Buff and Zamminer || have thrown a doubt over this 

 conclusion; but W. Weber f, who found it in general corro- 

 borated, expressed an opinion that the difference between these 



* Jbh. d. K. Sachs. Ges. d. Wissensch. 1852, i. p. 556. 

 f Pogg. Ann. vol. xlvii. p. 225. Bull, de VAc. d. St. Pet. vol. iv. p. 337. 

 t Phil. Mag. (4) vol. iii. p. 32. 



§ Pogg. Ann. vol. lxxix. p. 337; lxxxii. p. 181. Miiller, Fortschritte 

 er Phys. p. 502. 

 ** ||Lieb. u. Wohl., Ann. der Pharm. vol. lxxv. p. 83. 

 IT lb. p. 566. 



2H2 



