Prof. E. Bouty's Studies on Magnetism. 



93 



then interrupted; and then the needle is withdrawn (disruptive 

 discharge). 



The repetition of each of these processes furnishes an incre- 

 ment of magnetism to the needle; and, provided that all the 

 operations effected are of the same sort and the conditions iden- 

 tical, the results of the experiments are well represented by a 

 hyperbolic formula such as formula (1). The limit A appears 

 to be the same for the passages and the interruptions, but less 

 for the establishments. 



Table IV. — Needle 2 millims. in diameter, magnetized by 

 I Grove's element. 



Number of 

 establishments. 



Magnetic moment. 



Difference. 



Observed. 



Calculated. 



1 

 2 

 3 

 4 

 5 

 6 

 10 



5056 

 52-81 

 53 50 

 53 83 

 54-25 

 54-18 

 5475 



50-56 

 52-81 

 5356 

 53-93 

 54- 16 

 54-31 

 54-61 



000 

 0-00 

 -006 

 -0-10 

 +0-09 

 -013 

 +014 



A=5506, B=4-50. 



After the tenth passage, interruptions having been produced 

 unawares, the moment of the needle suddenly rose to 55*96, and 

 was not carried beyond that limit by 50 establishments. Ten 

 passages with the spiral then raised the magnetic moment to 

 57*56, and twenty more passages to 57*88. 



Table V. — Needle 2 millims. in diameter, magnetized by 

 1 Grove's element. 



Number of 

 interruptions. 



Magnetic moment. 



Difference. 



Observed. 



Calculated. 



1 



2 



32 



5315 

 55-93 

 5873 



5315 

 55 93 

 58-55 



000 



000 



+0-18 



that the permanent magnetism produced by a current A becomes more 

 considerable when the needle, after magnetization, has been submitted to 

 the action of a current B, feebler and in the opposite direction. If B is 

 made to tend to 0, the phenomenon still continues ; and this is not at all 

 surprising, since partial demagnetization (corresponding to loss of the tem- 

 porary magnetism) is the consequence of the cessation of the current A. 



