150 ANNUAL OF SCIE^'TIFIC DISCOVERYi 



nishcs a method for the determination of the nature of the salts 

 contained in the solution. 



MAGNETISM. 



M. Treve, in pursuing his researches on magnetism, has con- 

 ceived the design of submitting cast iron to an electro-magnetic 

 inlluonce. 



In the axis of a powerful bobbin, he lias placed a mould with 

 sand, which receives the jet of melted iron ; then he made an en- 

 ergetic current from 12 couples of Buusen's pass through it ; he 

 placed, at some distance from that, a small cylinder of the same 

 melted iron, withdrawn from all magnetic inlluence. As soon as 

 the cooling process was complete, he took the moulds, broke the 

 cylinders, and examined the grain of each of them. MM. Dou- 

 zel, iron-founders, have immediately studied it, and have found 

 no diflerence in crystallization. Two smaller patterns have been 

 exactly measured by M. Deleuil, which have only shown the 

 trilling difference of 3 milligrammes in tlieir weight. An impor- 

 tant fact is, however, revealed by these first attemj^ts. The pres- 

 ence of a powerful magnetism in the casting, from its liquid state 

 answered to 1,300 degrees, until the cooling was complete. The 

 cylinder of cast iron, hardly cold, attracted very strongly a largo 

 bar of iron. It has remained magnetized since its solidification, 

 magnetizing feebly, it is true, but, in short, characterized by its 

 two poles. It is proved, then, that no incompatibility exists be- 

 tween heat and magnetism, that is to sa3% that iron can be mag- 

 netized at any temperature, when the action is constant, as in 

 the experiment written above. M. Faye, in the session of the IGth 

 of August, 18G5, had shown a remarkable result, which is not 

 without analog}^ to that which we have just shown. 



After having dissolved in an acid some soft iron, destitute of 

 restraining force, and having deposited it in a thin layer upon the 

 surface of a sheet of copper, the illustrious academician estab- 

 lished in this iron, chemically pure (but rough and broken), a re- 

 straining faculty so energetic, that it has been able to heat a plate 

 thus prepared to the point of fusion of red copper itself, without 

 making the magnetism disappear that it had first communicated 

 to it. This plate has preserved its magnetism to this day. . . . 

 If now, as these analogous results tend to show, temperature 

 high or low is not incompatible with the existence of magnetism, 

 ichcn the first cause is persistent, as in the case of the earth, i)erpet- 

 ually submitted to the action of the currents which envelop it 

 from east to west, there would be some reason to accord more of 

 probability to the hypothesis of central magnetism, which ex- 

 plains more completely the variation and the inclination of the 

 magnetic needle, or, indeed, the ctuitre might be magnetic, what- 

 ever the temperature, might it not be this i)erpetual magnetism in 

 rotation from west to east, which determines in the surroimding 

 atmosphere the currents from east to west, which hayo been 

 established by AmpSre? — Comptes liendus, Feb. 1, 18G9, 



