46 On the magnetic Pheenomena 
inches, the effect was sensible; and it increased with the quan- 
tity of immersion. Two arrangements of this kind acted more 
powerfully than one; but when the two were combined so as to 
make the zine and copper-plates but parts of one combination, 
the effect was very much greater. This was shown still more 
distinctly in the following experiment. Sixty zine plates with 
double copper-plates were arranged in alternate order, and the 
quantity of iron filings which a wire of a determinate thickness 
took up observed: the wire remaining the same, they were ar- 
ranged so as to make a series of thirty; the magnetic effect ap- 
peared more than twice as great; that is, the wire raised more 
than double the quantity of iron filings. 
The magnetism produced by Voltaic electricity seems (the wire 
transmitting it remaining the same) exactly in the same ratio as 
the heat; and however great the heat of a wire, its magnetic 
powers were not impaired. This was distinctly shown in trans- 
mitting the electricity of twelve batteries of ten plates each of 
zinc, with double copper arranged as three, through fine pla- 
tinum wire, which, when so intensely ignited as to be near the 
point of fusion, exhibited the strongest magnetic effects, and at- 
tracted large quantities of iron filings and even small steel needles 
from a considerable distance. 
As the discharge of a considerable quantity of electricity through 
a wire seemed necessary to produce magnetism, it appeared pro- 
bable, that a wire electrified by the common machine would not. 
occasion a sensible effect; and this I found was the case, on 
placing very small needles across a fine wire connected with a 
prime conductor of a powerful machine and the earth. Butasa 
momentary exposure in a powerful electrical circuit was suffi- 
cient to give permanent polarity to steel, it appeared equally 
obvious that needles placed transversely to a wire at the time 
that the electricity of a common Leyden battery was discharged 
through it, ought to become magnetic; and this I found was ac- 
tually the case, and according to precisely the same laws as in 
the Voltaic circuit ; the needle under the wire, the positive con- 
ductor being on the right hand, offering its north pole to the 
face of the operator, and the needle above, exhibiting the opposite 
polarity. 
So powerful was the magnetism produced by the discharge of 
an electrical battery of 17 square feet highly charged, through a 
silver wire of = of an inch, that it rendered bars of steel of two 
inches long and from 1, to =; in thickness, so magnetic, as to 
enable them to attract small pieces of steel wire or needles ; 
and the effect was communicated to adistance of five inches above 
or below or laterally from the wire, through water or thick plates 
of glass or metal electrically insulated, 
The 
