326 B. Posing on the Participation of Matter 



dF ^F 



dpi dp\ 



whence, by comparing this equation with (28), we have 

 BF BF 



^ F J „ *V* JL.rr ^Pfi 4. X 



dpi dpi 



or, more simply, taking ^— = P a , _ =p ft . .-. .. 



BF _. f #q ^ 1 



BP " I a 3 log P a + %Hog P^ + ' ' ' ' / •=««*-> " ( d °> 



where is the absolute temperature, and P«, P^, . . . . are 

 supposed for simplicity to be only functions of this tempe- 

 rature and of the coordinates p a , p p , .... respectively. 



It is by this equation, in conjunction with equations (25), 

 (27), and (29), that the process of magnetization is completely 

 defined. -N-p 



First of all, it is to be seen from equation (30) that ^- 



is a positive quantity, as ,, ^ a p ? ,, ,p , . . . are, in general. 



greater than nil. it 



Therefore, as shown by equation (29), -yy is for a para- 



■magnetic substance always larger than k if only 



BF v 3 



dJ 2 ^ 2k . (2 



c-o 



When ^-p = o To \' ZE* S m ^ n ^ te ^ g rea t> and, lastly, 



if with increasing of H, and therefore of J 2 , ^-^ becomes 



v 3 . a^ 



> n To r? the equation cannot give real solutions, and 



statical magnetization is impossible. 



[In the latter case, as is easily proved, the process of mag- 

 netization represents a kind of free motion at a constant mag- 

 netic force. Nevertheless, the equations of this process are 



