1851.] OF THE ROYAL INSTITUTION. 3 
scribed as the centre of magnetic force,) a glass tube drawn to a 
point (as in the apparatus used for blowing the delicate soap-bubbles,) 
and filled with water ; by slowly withdrawing the water, the air could 
be drawn into the tube from any desired spot and tested. This was 
done; and it was found that even when the magnetic action was 
most intense, the proportions of the magnetic oxygen and of the non- 
magnetic nitrogen were undisturbed. —The following experiment 
proved that no condensation was produced on oxygen by the magne- 
tic power, 7. e. that it is not aggregated, as happens with iron filings 
when under the influence of the magnet. The flat-faced poles of 
the magnet were separated the 60th of an inch by a copper plate 
with an aperture in the middle, so that when the whole was clamped 
together a chamber was formed. By gauges attached to this chamber 
it was found that no trace of condensation occurred, however great 
was the magnetical force brought to bear on the oxygen. 
The loss of magnetical power occasioned by heat was then 
noticed. This was shown first in the case of iron heated to redness ; 
then in that of nickel raised to the temperature of boiling oil; and 
lastly, in the case of the air (7. e. of the oxygen in this air) by the 
following experiment :— Two conical poles a little separated were 
employed ; above was placed a piece of phosphorus on paper, and below 
a helix of platinum wire heated to redness by a small Grove’s battery 
independent of that used to excite the electro-magnet. The heated 
air, rising upwards from the helix, speedily inflamed the phosphorus 
above it whilst the electro-magnet was unexcited ; but when rendered 
active, the oxygen in the heated air becoming less magnetic, was dis- 
placed by the current of colder (and consequently more magnetical) 
oxygen, and the phosphorus in consequence remained unaffected by 
the mass which glowed beneath it, until the electro-magnet was 
deprived of its power; and then the natural laws of specific gravity 
came again into operation, the heated air rose, and the phosphorus 
was lighted. 
In conclusion, Mr. Faraday announced his intention of applying, on 
a future evening, the reasoning deducible from these and other experi- 
ments, to the variation of magnetic lines on the earth’s surface. His 
purpose then will be to compare the records of this varying force with 
the variations of temperature occasioned by the annual revolution of 
the earth, the varying pressure of the atmosphere, storms, &c. with 
the hope of supplying a true theory of the cause of the annual and 
diurnal, and many of the irregular variations of the terrestrial mag- 
netic power. 
For the papers in which these results are described more at large, 
see Philosophical Magazine, 1847, Vol. : xxx1, p. 401; and Philoso- 
phical Transactions for 1851, p. 1. 
Among the objects exhibited in the Library, were —a water-worn 
Lump of Gold, (weight 219 oz. 8 dwt. 12 gr.; value about £826,) 
from Carson’s creek, California [by the Governor of the Bank of 
? B2 
