TRANSACTIONS OF THE SECTIONS. 
33 
On the absence of Magnetism in Cast Iron when in fusion. 
R. W. Fox. 
In the course of some magnetic experiments, it appeared to the 
author desirable to ascertain whether a magnetic needle is acted 
upon by cast iron in a state of fusion. For this purpose he had a 
horizontal mould made in sand, about five feet long and two inches 
square, in the direction of the magnetic meridian; and at a very 
small distance from its northern extremity, and parallel to it, he 
placed the south pole of a delicately poised magnetic needle, the 
north pole of which extended beyond the mould. The latter was 
then filled with very fluid melted iron, but not the slightest effect 
was produced on the needle till after the metal had become fixed 
and cooled down to a cherry-red colour. The needle was then very 
suddenly attracted with great energy. Sand and a copper plate 
were employed to protect it from the hot iron. 
This experiment may perhaps be considered by those who advo¬ 
cate the existence of a high temperature in the interior of the earth, 
as tending to strengthen the arguments in favour of the agency of 
electricity in producing terrestrial magnetism, seeing that intense 
heat and fixed magnetism, in the ordinary acceptation of the term, 
cannot, apparently, exist together.* 
On Electric Currents 'passing through Platinum Wire. By William 
Barker, M.D. 
When the large deflagrating battery was used on two occasions 
in the Chemical School of Trinity College, Dr. Barker observed that 
on passing the current of electricity through a piece of platina wire, 
about three feet in length, and igniting it, there were dark portions 
of the w r ire of about ^ or 4- an inch in length at intervals of from 
three to four inches in its whole length, the same parts of the w r ire 
being in the same condition during the time that the wire remained 
ignited. The author was unable at the time, owing to the number 
of experiments to be tried with the battery, to take any measure¬ 
ments or to examine whether wires of different diameters w'ere dif¬ 
ferently affected. The fact was stated for the consideration of the 
Section, reserving for further examination the law by which the di¬ 
stances and dimensions of these unignited portions of the electrified 
wire are governed, whether their distances are constant, or vary ac¬ 
cording to the size and material of the wire employed or the quan¬ 
tity or intensity of the galvanic currents. 
* [Mr. Peter Barlow had shown, many years since, that all magnetic ac¬ 
tion was lost by iron when raised to a white heat. See Phil. Trans. 1822, or 
Phil. Mag., first series, vol. Ix. p. 345.] 
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