Intelligence and Miscellaneous- Articles. 255 



of the bar, it is seen to pass through a maximum, of which the 

 temperature varies with the nature of the steel, but is always below 

 the temperature of magnetization ; if the heating is continued, the 

 magnetism definitively vanishes. On leaving the temperature 

 below that corresponding to the maximum, and letting the bar cool 

 and then reheating it, the second maximum is found to be below 

 the first, and so on. This property belongs solely to magnetism 

 received at a high temperature and lost in consequence of cooling. 

 When a bar which has received partial magnetization by contact 

 with a magnet, or conserved after heating, is heated, the magnet- 

 ism is seen to diminish more or less rapidly, but without there 

 being any augmentation. 



We have studied bars of divers compositions and different sec- 

 tions. Varying also the manner of heating, the quantities of 

 magnetism conserved at the same temperatures have shown them- 

 selves to be different; but we have constantly observed these three 

 phenomena : — 



(1) The conservation of the magnetism at any temperature 

 when that temperature is maintained constant ; 



(2) The diminution, at first slow, of the magnetism, becoming 

 very rapid after a time variable with the temperature of magneti- 

 zation ; 



(3) The augmentation of the quantity of magnetism remaining 

 after cooling when the magnet is reheated. 



The operations were performed in the laboratory of the Sor- 

 bonne. — Comptes Bendus de VAcademie des Sciences, Jan. 24, 1876, 

 vol. lxxxii. pp. 276-278. 



ON THE PHENOMENA OF INDUCTION. BY M. MOUTON. 



The experiments which have been made and the theories formed 

 in regard to induction-phenomena have generally referred to an 

 induced wire included in a circuit ; the electricity set in motion 

 passed from one extremity to the other, either through the wire 

 of a galvanometer or a magnetizing spiral, or through the air under 

 the complex form of the spark. But we may ask, into what rela- 

 tive electric condition does the phenomenon of induction bring the 

 two extremities of the wire of an induction-coil when no metallic 

 communication is established between them, and when they are 

 kept at too great a distance for the spark to clear it ? 



For the purpose of solving this problem, I made use of a Thom- 

 son's dial electrometer of large size ; the needle was maintained 

 charged by its communication with one of the poles of an open 

 pile ; and the two pairs of dials were, at a suitable time, connected 

 with the ends of the wire by the intermedium of a condenser with 

 a stratum of air. If, limiting ourselves to the case of the rupture 

 of the inducing current, we suppose a commutator putting, at the 

 same time that it produces that rupture, the ends of the induced 

 wire, in communication with the dials of the electrometer, the fol- 

 lowing is what will be observed. 



