magnetic phenomena produced by electricity. 13 
ought to become magnetic; and this I found was actually 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 op- 
posite 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 ^ to ^ in thickness, so mag- 
netic, as to enable them to attract small pieces of steel wire 
or needles ; and the effect was communicated to a distance of 
five inches above or below or laterally from the wire, through 
water or thick plates of glass or metal electrically insulated. 
The facility with which experiments were made with the 
common Leyden battery, enabled me to ascertain several 
circumstances which were easy to imagine, such as that a 
tube filled with sulphuric acid of ~ of an inch in diameter, 
did not transmit sufficient electricity to render steel magnetic ; 
that a needle placed transverse to the explosion through air, 
was less magnetized than when the electricity was passed 
through wire ; that steel bars exhibited no polarity (at least 
at their extremities) when the discharge was made through 
them as part of the circuit, or when they were placed parallel 
to the discharging wire ; that two bars of steel fastened 
together, and having the discharging wire placed through 
their common centre of gravity, showed little or no signs of 
magnetism after the discharge till they were separated, when 
they exhibited their north and south poles opposite to eacn 
other, according to the law of position. 
