200 Dr. E. Bouty on the Magnetization of Steel by Currents. 



in which A x and A 2 , & and /3 2 have the characteristic values 

 of the temporary and the permanent magnetization to satura- 

 tion ; moreover'^! and c 2 are determined by the following con- 

 ditions: — 



(1) The first term, containing the temporary coefficients, 

 represents the total temporary moment which the bar innocent 

 of magnetization would receive from a first application of the 

 magnetizing force F employed. 



(2) The second term is the difference between the perma- 

 nent moment of saturation and the permanent moment which 

 the force F is capable of producing. Thus, let a x and « 2 be 

 the temporary and permanent capacities of the bar for the force 

 F, we have 



CiAi=«i, | ^ 



c 2 A 2 =A 2 — « 2 - * 



Applying Biot's method of reasoning, we shall be led to re- 

 present the distribution of the magnetism, in the bars consi- 

 dered, by the formula 



<?2-fg2 e 2-J-£2 



The magnetic distribution is the superposition of two distri- 

 butions: — the one short (temporary), equal to that which a 

 first application of the force F would produce ; the other long 

 (permanent), equal to the residue of the primitive distribution 

 diminished in quantity by the portion of permanent magnetism 

 corresponding to F. The curious part of the matter is, that 

 the totality of the short distribution is not borrowed from the 

 primitive permanent distribution: new magnetism is called up 

 from the molecular depths to form the difference u x — a 2 ; while 

 a portion (often very considerable) A 2 — # 2 of the primitive 

 magnetization remains distributed after the permanent fashion 

 (long distribution), as if insensible to the action of the mag- 

 netizing force. This fact seems to me highly important in 

 regard to the theory of magnetism. 



In the following Tables examples are given of the applica- 

 tion of formulae (3) and (4). They refer to bars of 1 centim. 

 diameter. 



