200 Prof. A. Stoletow on the Magnetization- Functions 



Differentiating this last equation, we get = c dd + \c 2 d(f> } or 

 d6 __ \c q 

 dcf) c l 



42. Assuming that c l and c 2 are positive quantities in the 

 expressions for u, v, iv in art. 41, it will be seen that those values 

 were formed so that 6 and (/> each decrease with the motion. 



Hence —will be positive, and \ must be a negative quan- 

 tity. According to the supposed directions of the decrements, 

 the spiral motion will be dextrorsum. If the motion were 

 assumed to be such that dd and dcf) had different signs, the 

 spiral motion would be sinistrorsum, and we might by the same 

 reasoning as before obtain C = c l + \'c 2 <j) t c Y and c 2 being still 



positive. In that case -=rr = - = a negative quantity, and A/ 



is consequently positive. As the factors X and A/ are wholly 

 arbitrary, we have thus shown that, as far as hydrodynamics is 

 concerned, the galvanic current might be either dextrorsum or 

 sinistrorsum. 



Having in the preliminary part of this communication dis- 

 cussed the action of a large magnet on a small one, and having 

 now ascertained the exact form of a galvanic current along a cir- 

 cular wire, I propose in a second Part to investigate the action 

 of a galvanic? coil on a small magnet, and to show why it agrees 

 approximately with that of a magnet, and in what respect espe- 

 cially the two actions differ. In the course of the investigation 

 the facts on which Ampere's theory rests will be accounted for 

 by the hydrodynamical theory, for the purpose of fully establish- 

 ing the claim of the latter to be considered a strictly a priori 

 theory. 



Cambridge, August 10, 1874. 



XXX. On the Magnetization-Functions of various Iron Bodies. 

 By Professor A. Stoletow*. 



IN my work on the magnetization of ironf I have taken 

 Neumann's coefficient k as a measure of the magnetizability. 

 This, as is well known, expresses the ratio in which the magnetic 

 moment, referred to the unit of volume, stands to the quantity 

 of the magnetizing force, presupposing that the iron forms an 



* Translated from a separate impression communicated by the Author, 

 from the Bulletin de la Societe Imp. des Naturalistes de Moscou, 18/3, 

 No. 4. 



t Pogg. Ann. vol. cxliv. p. 439; Phil. Mag. S. 4. vol. xlv. p. 40 ; more 

 fully as a separate brochure in Russian, Moscow, 18/2. 



