Chemical Science. ae’ 
in the galvanometer just as a magnetic needle would be, and a 
Wollaston’s pile of 10 pair of plates connected with the wires of the 
instrument. 
A needle of soft iron instantly placed itself parallel to the axis of 
the spirals, the arrangement of magnetism in it being similar to that 
of a common bar magnet. 
Deutoxide of iron enclosed in asmall paper cartridge 0.157 of inch 
in diameter, and properly suspended, was rapidly drawn into the 
plane of the apparatus, and took a position perpendicular to the axis 
of the spirals; but soft iron filings similarly circumstanced acted just 
like the iron needle. 
The difference exhibited in this way between these two sub- 
stances does not exist in Coulomb’s manner.of making the experi- 
ment, and hence a difference of action would seem to be indicated 
between the electro-magnetic wire and magnetic poles. 
Needles of copper, wood, or gum Jac, were affected like the 
deutoxide of iron, but in a smaller degree; but great caution is re- 
quisite in making these experiments to avoid currents of air; this is 
best done by closing the extremities of the galyanometer in glass. 
Needles thus affected by the electric current were then examined 
as to their action on a feeble magnet. The iron needle was found 
to act like a regular magnet, and it is to be presumed that the car- 
tridge of iron filings did so also ; but the parcel of deutoxide of iron, 
when examined, was found to act with one pole of the bar in the 
same manner at every point situated towards one side of the galvano- 
meter, and inversely when the pole was changed, so that the north 
Magnelism was on one side of the needle, and the south on the 
other. It is, however, possible to distribute the magnetism as in the 
common needle, which is done by retaining the cartridge for some 
time parallel to the axis of the instrument; but when left to itself, 
it returns gradually to the state described. ‘The action of the magnet 
on the other needles, when in the galvanometer, gave no certain 
results. 
A needle of wood about 1 inch in length, and .04 of an inch 
in diameter, had fixed at each extremity a square plate of steel or 
soft iron .08 of an inch in the side, and .008 of an inch in thickness, 
when placed in the spiral it was rapidly drawn into a position pa- 
rallel to the plane of the spirals, the distribution being as in the car- 
tridge of deutoxide. Two pieces of iron wire 0.04 of an inch in 
length were then put in place of the plates, and now the needle 
stood in the instrument at an angle of 45° with the plane of the 
spirals, or with its axis; as the length of the ends of iron wire was 
increased the needle tended more to parallelism with the axis, 
and when these extremities were 0,4 of an inch long, the needle stood 
parallel to the axis of the instrument.—Ann. de Chim. xxv. 269. 
3. On Electro-motive Actions produced by the contact of Metals and 
