757 
were kept at some distance above the level of the liquids, andas a 
further precaution, the portions not in contact with the ore were 
coated with sealing-wax. ‘The liquids in both branches were at the 
same level, and corks were inserted to retain the pyrites in the same 
positions. This apparatus ‘remained undisturbed for: three days, 
when the column of the solution of sulphate of copper was found to 
have increased in height at the expense of the water in the other 
branch, the difference being about one-tenth of an inch.. On the 
copper pyrites in the solution of sulphate of copper being examined, 
it was found to be partly coated with metallic copper. . j 
Both these effects were, therefore, produced, Mr. Fox observes, 
solely by means known to exist in the earth, and the experiments, 
he adds, seem, therefore, to have a direct and unequivocal bearing, not 
only on the decomposition of metallic salts under the surface, but on 
the causes which affect the different levels of subterranean springs, 
and the purification of water from bodies which it may hold in solu- 
tion. 
A memoir “ On the Elevation and Denudation of the District of 
the Lakes of Cumberland and Westmoreland.” By William Hop- 
kins, Esq-, F.G.S., was then laid before the Society. 
The general structure of this district has been long known to 
geologists through the labours of Professor Sedgwick and other 
geologists. The object uf this paper is to afford theoretical expla- 
nations of the observed phenomena of elevation and. denudation. 
The general boundary of tract may be considered as sufficiently 
defined on the north by the band of mountain limestone which runs 
from Kirkby Stephen by Heskel, on the west by the coast, and on 
the south by the discontinuous and irregular band of limestone, 
which again nearly meets the great mountain limestone ridge of 
Yorkshire, by which, and the great fault along its base, the district 
is bounded on the east. The general strike of the limestone beds 
at any point, as well as that of the new red sandstone reposing upon 
them, coincides with the direction of the boundary at. that point, 
except on the east, where the boundary is the great fault just men- 
tioned. Consequently the dip is nearly perpendicular to the bound- 
ary, and round the western side is divergent from the extremity of 
the axis of the district, which may be considered to extend from 
near Scaw Fell over Kirkstone and Howgile Fells. On the west 
the dip frequently amounts to between 20° and 30°; and it should 
be remarked, that it appears to be very nearly as great in the new 
red sandstone beds as’ in those of the subjacent. limestone. The 
mountain limestone reposes unconformably on the older formations 
which, within the limestone band, occupy the surface. The gene- 
ral strike appears to be somewhat north of N.E. and.south of S.W. 
The surface of junction of the mountain limestone and the older 
formations beneath can be well examined in many places, and the 
author concludes that the surface on which the limestone was de- 
posited must have been an even surface in, the same sense in which 
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