390 Foreign Literature and Science. 



placed above the same spiral, the needle took the opposite 

 direction. 



A platina wire which formed part of the voltaic circuit, 

 strongly attracted iron filings, (as Mr. Arago had observed 

 with respect to copper.) A tin wire did the same, but mel- 

 ted almost instantly. 



The following experiment was made with the common 

 electric machine : — 



A needle was placed within an iron spiral, and the Leyden 

 bottle was discharged through the latter. The needle was 

 magnetized but not the spiral. This was repeated many 

 times with the same results. 



M. A. Van Beck, of the Philosophical Society of 

 Utrecht in Holland, also states the results of an experiment 

 with a single combination of copper and zinc. The zinc 

 plate was 3600 centimetres, (about 1440 inches,) square, 

 and the plates of copper were, as in the Florence machine, 

 formed into a trough which contained the fluid, consisting of 

 sixty parts water, one part sulphuric acid, and one part 

 nitric. 



The galvanic current being disposed in a direction paral- 

 lel to the magnetic meridian, caused a needle eight inches 

 long to decline 70° to the E. and to the VV. according as it 

 was placed above or below the conductor ; whilst with a 

 very small and susceptible needle, the galvanic current 

 seemed to prevail entirely over the teri'estrial magnetism, in 

 giving it a declination of 90^. 



The conjunctive wire, in this instrument, also attracted 

 iron filings very forcibly. The filings remained attached to 

 it as long as the poles were united, but fell off immediately 

 on the cessation of the current. 



A small bar of steel was perfectly magnetised, by M. Van 

 Beck, in five minutes, by placing it in a tube of glass sur- 

 rounded spirally by a brass wire which formed the connec- 

 tion. The north pole is formed on the negative side when 

 the spiral is wound from the right, and on the positive, 

 when it is wound from the left. He also proved that steel 

 may be magnetised in the same manner with great facility 

 by the common electric machine, by a discharge of the bat- 

 tery through the brass spiral, or even that of a Leyden bot- 



