WITH MAGNETISM AND ELECTRICITY. 177 



by reference to an ideal distribution of magnetic fluids upon the 

 surface ; then, for the true interior condition of the body, four 

 different possibihties may be thought of, and thus four different 

 cases distinguished, which have been above stated and dis- 

 cussed. Two of these cases rested on the assumption that two 

 magnetic fluids exist, either in the rotatory molecules of the 

 body, immoveable, but in constant separation ; or in non-rota- 

 tory molecules, moveable, and in variable separation. The two 

 other cases, on the contrary, rested on the assumption that the 

 two electric fluids existed either in a definite circuit round each 

 rotatory molecule of the body in constant motion, or round each 

 non-rotatory molecule in variable motion. These four cases do 

 not by any means reciprocally exclude each other ; for it is easy 

 to see that a portion of the magnetic fluids may remain con- 

 stantly separated in rotatory molecules, while the separation of 

 another portion is variable ; and in the same way a portion of 

 the electric flux in given circular paths round rotatory mole- 

 cules may be constant, while another portion in circular paths 

 round non-rotatory molecules varies in intensity. In the latter 

 respect, indeed, when we consider the numerous electromotive 

 forces present, the existence of a constant flux without a variable 

 portion is perfectly inconceivable ; for the electric fluids, \ifree 

 to move in definite paths, as the existence of constant currents 

 proves, must necessarily obey the impulsion of the electromotive 

 forces decomposed in the direction of these paths. Neverthe- 

 less the above four cases may be combined pair- wise to two 

 principal cases, each of which, if actually established, would 

 leave the other in the position of a quite superfluous hypothesis, 

 namely, — 1st, that magnetic fluids exist, which with the mole- 

 cules, or in them, are capable of motion ; 2ndly, that the elec- 

 tric fluids, which, according to the doctrine of electricity, are 

 everywhere present, move without resistance in definite circular 

 paths around the molecules. 



For each of these two principal cases a theory may be deve- 

 loped, and each of these theories may be divided into two por- 

 tions, in one of which the results of both theories coincide, and 

 in the other of which they contradict each other; for these 

 theories are similarly circumstanced to the theories of emission 

 and of undulation in optics, which likewise in many respects 



