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

ancient in reference to the earth's history, or,
like the course of the present rivers and the acs
tual shape of our hills and valleys, are ti,ey only
of high antiquity when contrasted with the brief
space of human annals ? May they not be like
Vesuvius and Etna, which, although they have been
adding to their finks in the course of the lase 2,000
years many a stream of lava and shower of ashes,
were still mountains very much the same as they
now are in height and dimensions from the earliest
times to which we can trace back their existence ?
Yet although their foundations are tens of thou•
sands of years old, they were laid at an era when
the Mediterranean was already inhabited by the
same species of marine shells as those with which
it is now peopled; so that these volcanoes must be
regarded as things of yesterday in the geological
calendar. It has been ascertained that the hot
springs of the Pyrenees, the Alps, and many other
regions, are situated in lines along which the rocks
have been rent, and usually where they have been
displaced or " faulted," Similar dislocations in the
solid crust of the earth are generally supposed to
have determined the spots where active and extinct
volcanoes have burst forth, for several of these often
affect a linear arrangement, their position seeming
to have been determined by great lines of fissure.
Another connecting link between the volcano and
the hot spring is recognisable in the great abun-
dance of hot springs in regions where volcanic
eruptions still occur, It is also in the same districts
that the waters occasionally attain the boiling tem•
perature, while some of the associated stufas emit
steam considerably above boiling point. But in
proportion as we recede from the great centres of
igneous activity we find the thermal waters de-
creasing in frequency and in their average heat,
while at the same time they are most conspicuous
in those territories where, as in Central France or
the Eifel in Germany, there are cones and craters
still so perfect in their form, and streams of lava
bearing such a relation to the depth and shape of
existing valleys, as to indicate that the internal
fires have become dormant in comparatively recent
times. If there be exceptions to this rule, it is
where hot springs are met with in the Alps and Py-
renees that have been violently convulsed by earth-
quakes. The thermal waters:of Bath are far from
being conspicuous among European hot springs,
for the quantity of mineral matter contained in them
in proportion to the water which acts as a solvent ;
yet Professor Ramsey has calculated that if the
eulphates of lime and soda, and the chlorides of
sodium and magnesium, and the other mineral ins
gredients they contain, were solidified, they would
form in one year a square column 9 feet in diameter
and no less than 140 feet in height. All this matter
is now quickly conveyed by a stream of limpid
water, in an invisible form, to the Avon, and by the
Avon into the sea; but if, instead of being thus re-
moved, it were deposited round the orifice of erup-
tion, like the siliceous layers which encrust the
circular basin of an Icelandic geyser, we should soon
see a considerable cone built up, with a crater in
the middle ; and if the action of the spring were
intermittent, so that ten or twenty years should
elapse between the periods when solid matter was
emitted, or (say) an interval of three centuries, as
in the case of Vesuvius between 1306 and 1631, the
discharge would be on so grand a scale as to afford
no mean object of comparison with the intermittent
outpourings of a volcano. Dr. Daubeny, after de-
voting a month to the analysis of the Bath watera,
in 1833, ascertained that the daily evolution of
nitrogen gas amounted to no less than 250 cubic
feet in volume. This gas, he remarks, is not only
characteristic of hot springs but is largely disen-
gaged from volcanic craters during eruptions. It
will, however, of course be admitted, as Professor
Bischoff has pointed out, that in some places organic
matter has supplied a large part of the nitrogen
evolved. Carbonic acid gas is another of the
volatilised substances discharged by the Bath
waters. The calculations made by the eminent
German chemist (Dr. Gustav Bischoff) of the exact
amount of distension which the origin of new
mineral products may cause, by adding to the vo-
lume of the rock, deserve the attention of geologists,
as affording them aid in explaining those reiterated
oscillations of level—those risings and sinkings
of land—which have occurred on so grand a
scale at successive periods of the past.
There are, very probably, many distinct
causes of such upward, downward, and la-
teral movements, and any new suggestion on this
head is most welcome; but I believe the expan-
sion and contraction of solid rocks, when they
are alternately heated and cooled, and the fusion
and subsequent consolidation of mineral masses, will
continue to rank,eis heretofore, as the most influential
causes of such movements. The temperature of the
Bath waters varies in the different springs from 117
deg. to 120 deg. Fahrenheit. This, as before stated,
is exceptionally high, when we daly allow for the
great distance of Bath from the nearest region of
active or recently extinct volcanoes and of violent
earthquakes. The hot springs of Aix-la-Chapelle
have a much higher temperature—via., 135 deg.
Fahrenheit—but they are situated within 40 miles
of those cones and lava streams of the EVel which,
though they may have spent their force ages before
the earliest records of history, belong neverthelss
to the moat modern geological period. Bath is about
400 miles distant from the same part of Germany,
and 440 from Auvergne—another volcanic region—
the latest eruptions of which were geologically
coeval with those of Eifel. When these twe re-
gions in France and Germany were the theatres
of frequent convulsions, we may well suppose that
England was often more rudely shaken than now
—and such shocks as that of Octoberalast, the sound
and rocking motion of which caused so great a sen-
sation as it traversed the southern part of the
island, and seems to have been particularly violent
in Herefordshire, may be only a languid reminder
to us of a force of which the energy has been gra-
dually dying out. I have little doubt that the
Bath springs, like most other thermal waters,mark
the site of some great convulsion and fracture
which took place in the crust of the earth at some
former period—perhaps not a very remote one,
geologically speaking. If we adopt the theory that
the nitrogen is derived from the deoxidation of
atmospheric air carried down by rain-water, we
may imagine the supply of this water to be fur-
nished by some mountainous region, possibly a dis-
tant one, and that it descends through rents or
porous rocks till it encounters some mass of heated
matter by which it is thus converted into steam,
and then driven upwards through a fissure. In its
downward passage the water may derive its sul-
phate of lime,' chloride of calcium, and other sub-
stances from the decomposition of the gypsous
calcareous, and other constituents of the rocks
which it permeates. The greater part of the ingre-
dients are common to sea-water, and might suggest
the theory of a marine origin; but the analysis of
the Bath springs by Merch and Galloway shows
that the relative proportion of the solid matter is far
from agreeing with that of the sea. That some
mineral springs, however, may derive
an inexhaus-
tible supply, through rents and porous rocks, from
the leaky bed of the ocean, is by no means an un-
reasonable theory, especially if we believe that the
contiguity of nearly all the active volcanoes to the
sea is connected with the access of salt water to the
subterranean foci of volcanic heat. Professor Roscoe,
of Manchester, has been lately engaged in making
a careful analysis of the Bath waters, and has dis-
covered in them three metals which they were not
previously known to contain—namely, copper,
strontium, and lithium ; but he has searched in vain
for caesium and rubidium, those new metals, the
existence of which has been revealed to us in the
course of the last few years by what is called spec-
ruPr Professor Bunsen, of Heidelberg,
d
in the application of this new
led the
h e way analysis.
in 1860,
test to the hot waters of Baden-Baden and of Durk-
heim in the Palatinate. He observed is the spectrum
some coloured lines of which he could not interpret
the meaning, and was determined not to rest till he
had found out what they meant. This was no easy
task, for it was necessary to evaporate 50 tons of
water to obtain 200 grains of what proved to be two
new metals. Taken together, their proportion to the
water was only as one to three millions. He named
the first caesium, from the bluish-grey lines which
it presented in the spectrum; and the second rubt-
dium,.from its two red lines. Since these successful
experiments was made, thallium, so called from its

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. It 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 cons
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—CtO3iUM, never before detected in any
mineral spring in England; but its peculiar characs
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
widelysdiffased substance, existing in minute quan-
tities 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.
tine, 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 Dukinfield 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,silver,
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 lea•
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
molecul-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-
clusion 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 pros
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 Fehr., and were con-
veyed by the Romans 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, and 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 quartz 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 belongs 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
altimihous and some other minerals, and therefore plays no
small part in the composition of the earth's crust, is 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 groat pressure affords
no argument against our at,ributing 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 cf 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
of 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 1853, 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
instruments, abstracting slowly from the subterranean mol-
ten mass that heat which clouds of vapour are 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,
bot I infer it from the mighty changes which this region has
und,'rgone since the time when the British seas, rivers, and
lakes N‘'ere inhabited by the existing species of Testacea. It
is already' more than a quarter of a century since Sir Rode-
rick Murchison first spoke of the Malvern Straits, meaning
thereby a channel
of the sea which once separated Wales
from England, That
.Ruch marine straits really extended,
at a modern period, between what are LJW the
estuaries of the Severn• and the Dee, has been
lately confirmed in a satisfacCU manner by the dis-
covery of marine shells of ,'tent species of drift
covering the water-sheds which di .'ides those estuaries.
At the time when these shells were the Cotswold
Hills, at the foot of which this city is built,Ormed one of
the numerous islands of an archipelai to into 1440 h Eng-
land, Ireland, and Scotland were then divided. The agtotoun
of vertical movement which would be nsvesisarY
t4attio_
such a state of the surface as prevailed when in
the to re n
oref
land and sea were so different would be very great. Ao.
where in the world, according to our present information,
is the evidence of upheaval, as raanifer.ed by upraised
marine shells, so striking as in Wales. The whole fauna
bears testimony to a climate colder that, that 13 Ny experi-