The Sun.
London, England, 1864-09-15 00:00:00

green line, was discovered in 1861 by Mr. Crookes ;

and a fourth metal, named indium, from its indigo-

coloured band, was detected by Professor Richter, of
Freiberg, in Saxony, in a zinc ore of the Hartz. It
is impossible not to suspect that the wonderful effi-
cacy of some mineral springs, both cold and thermal,
in curing diseases, which no artificially prepared
waters have as yet been able to rival may be connected
with the presence of one or more of those elementary
bodies previously unknown ; and some newly-found
ingredients, when procured in larger quantities, may

furnish medical science with means of combating

diseases which have hitherto baffled all human skill.

While I was pursuing my inquiries respecting the
Bath waters, I learned casually that a hot spring
had been discovered at a great depth in a copper
mine near Redruth, in Cornwall, having about as

high a temperature as that of the Bath waters, and
of which, strange to say, no account has yet been
published. IC seems that, in the year 1839, a level
was driven from an old shaft, so as to intersect a

rich copper mine at the depth of 1,350 feet from the
surface. Through the contents of the lode a power.
ful spring of hot water was observed to rise, which

has continued to flow with undiminished strength

ever since. At my request, Mr Horton Davey, of
Redruth, had the kindness to send up to London
many gallons of this water, which had been ana-
lysed by Professor Wm. Allen Miller, F.R.S., who
finds that the quantity of solid matter is so great as
to exceed by more than four times the proportion of
that yielded by the Bath waters. Its composition
is also in many respects very different ; for it con•
tains but little sulphate of lime, and is almost from
the salts of magnesium. It is rich in the chlorides
of calcium and sodium, and it contains one of the
new metals—caesium, never before detected in any
mineral spring in England ; but its peculiar charac.
teristic is the extraordinary abundance of lithium,
of which a mere trace had been found by Professor
Roscoe in the Bath waters, whereas in this Cornish
hot spring this metal constitutes no less than a 26th
part of the whole of the solid contents, which, as
before stated, are so voluminous. Lithium was first
made known in 1817 by Arfvedsen, who extracted
it from petalite ; and it was believed to be extremely
rare until Bunsen and Kirchhoff, in 1860, by means
of spectrum analysis, showed that it was a most
widely .diffused substance, existing in minute quan-

titles in almost all mineral waters and in the sea,
as well as in milk, human blood, and the ashes of
some plants. It has already been used in medi-
cine, and we may therefore hope that, now that
it is obtainable in large quantities, and at
a much cheaper rate than before the Wheal
Clifford hot spring was analysed, it may become
of high value. When we compare the temperature
of the Bath springs, which issue at a level of less
than 100 feet above the sea, with the Wheal Clif-
ford spring, found at a depth of 1,350 feet from the
surface, we must of course make allowance for the
increase of heat always experienced when we de-

scend into the interior of the earth. The difference
would amount to 20 deg. Fahr., if we adopt the
estimate deduced by Mr Hopkins from an accurate
series of observations made in the Monkwearmouth
shaft, near Durham, and in the Dukiufield shaft,
near Manchester, each of them 2,000 feet in depth.

Hot springs are for the most part charged with
alkaline and other highly soluble substances, and as
a rule are barren of the precious metals, gold,eilver,
and copper, as well as of tin, platinum, lead, and
many others, a slight trace of copper in the Bath
waters being exceptional. But there are other
characters in the structure of the earth's crust more
mysterious in their nature than the phenomena of
metalliferous veins,on which the study of hot springs
has thrown light—l allude to the metamorphism of
sedimentary rocks. Strata of various ages, many of
them once full of organic remains, have been ren-

dered partially or wholly crystalline. It is admitted
on all hands that heat has been instrumental in
bringing about this re-arrangement of particles,
which when the metamorphism has been carried out
to its fullest extent, obliterates all trace of the im-

bedded fossils. But as mountain masses many miles
in length and breadth, and several thousands of feet
in height, have undergone such alteration, it has
always been difficult to explain in what manner an
amount of heat capable of so entirely changing the
molecu!ar condition of sedimentary masses could
have come into play without utterly annihilating
every sign of stratification as well as of organic
structure. Various experiments have led to the con-
c;usion that the minerals which enter most largely
into the composition of the metamphoric rocks have
not been formed by crystallising from a state of
fusion or in the dry way, but that they have been
derived from liquid solutions in the wet way—a pro-
cess requiring a far less intense degree of heat. The
changes which Daubree has shown to have been pro-
duced by the alkaline waters of Plombieres, in the
Vosges, are more especially instructive. These thermal
waters have a temperature of 160 deg Fahr., and were con-
veyed by the Itomens to baths through long conduits or
aqueducts. The foundations of some of their works con-
sisted of a bed of concrete made of lime, fragments of brick,
and sandstone. Through this and other masonry the hot
waters have been percolating for centuries, and have given
rise to various zeolites—apophyllite and chabazite among
others; also to calcareous spar, arragonite, an; fluor spar,
together with siliceous minerals, such as opal, all found in
the interspaces of the bricks and mortar, or constituting
part of their re-arranged materials. The quantity of heat
brought into action in this instance in the course of 2,000
years has no doubt been enormous, although the intensity of
it developed at any one moment has been always inconsider-
able. The study of late years of the constituent parts of gra-
nite has in like manner led to the conclusion that their con•
solidation has taken place at temperatures far below those
formerly supposed to be indispensable. Gustav Rose has
pointed out that the qaartk of granite has the specific gra•
vity of 2.6, which characterises silica when it is precipitated
from a liquid solvent, and not that inferior density, namely
2'3, which balonga to it when it cools and solidifies in the
dry way from a state of fusion. But some geologists, when
made aware of the intervention on a large scale of water in
the formation of the component minerals of the granitic and
volcanic rocks, appear of late years to have been too much
disposed to dispense with intense heat when accounting for
the formation of the crystalline and unstratified rocks. As
water in a state of solid combination enters largely into the
aluminous and some other minerals, and therefore plays no
small part in the composition of the earth's crust, it follows
that when rocks are melted water must be present, inde-
pendently of the supplies of rain water and sea water which
find their way into the regions of subterranean heat. But
the existence of water under great pressure affords
no argument against our atlibuting an excessively
high temperature to the mass with which it is
mixed up; Still less does the point to which the melted
matter must be cooled down before it consolidates or
crystallises into lava or granite afford any test of the
degree of heat which the same matter must have acquired
when it was melted and made to form lakes and seas in the
interior of the earth's crust. We learn from Bunsen's ex-
periments on the Great Geyser in Iceland, that at the depth
of only seventy-four feet, at the bottom of the tube, a column
o water may be in a state of rest, and yet possess a heat of
120 deg. Centigrade, or 24 deg. Fahrenheit. What, then,
may not the temperature of such water be at the depth of a
few thousand feet ? It might soon attain a white heat under
pressure ; and as to lava, those who have beheld it issue, as
I did in 1858, from the south-western flanks of Vesuvius,
with a surface white and glowing like that of the sun, and
who have felt the scorching heat which it radiates, will form
a high conception of the intense temperature of the same
lava at the bottom of a vertical column several miles high,
and communicating with a great reservoir of fused matter,
which, if it were to begin at once to cool down, and were
never to receive future accessions of heat, might require a
whole geological period before it solidified. Of such slow
refrigeration hot springs may be among the most effective
instrunients, abstracting slowly from the subterranean mol-
ten mass that heat which clouds of vapour arc seen to carry
off in a latent form from a volcanic crater during an erup •
tion, or from a lava stream during its solidification. I hinted
at the beginning of this address, that the hot springs of
Bath may be of no high antiquity, geologically speaking—
not that I can establish this opinion by any positive proofs,
but I infer it from the mighty changes which this region has
undergone since the time when the British seas, rivers, and
lakes were inhabited by the existing species of Testacea. It
is already more than a quarter or a century since Sir Rode-
rick Murchison first spoke of the ]Malvern Straits, meaning
03ereby a channel of the sea ve.iich once separated Wales
from England, That such marine straits really extended,
at a modern period, between what are now the
estuaries of the Severn and the Dee, has been
lately confirmed in a satisfactory manner by the dis-
covery of marine shells of recent species of drift
covering the water-sheds which divides those estuaries.
At the time when these shells were living, the Cotswold
Hills, at the foot of which this city is built, formed one of
the numerous islands of an archipelago into which Eng-
land, Ireland, and Scotland were then divided. The amount
of vertical movement which would be necessary to restore
such a state of the surface as prevailed when the position of
land and sea were so different would be very great. No-
where in the world, according to our present information,
is the evidence of upheaval, as manifested by upraised
marine shells, so striking as in Wales. The whole fauna
bears testimony to a climate colder than that now wiped-