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 ace

nal shape of our hills and valleys, are they 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 flanks in the course of the last, 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 " fsulted," 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
effect a linear arrangement, their position seeming
_ _ _

;o 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 indicato that the internal

fires have b€come dormant in comparatively recent
times. If there be exceptions to this rule, it is
where hot springs are met with in the Alps and Pr

renees that have been violently convulsed by earth-

quake'. The thermal waterslof Bath are fir from
being conspicuous among European hot springs,
for the quintity of mineral matter contained in them
in proportion to the water which acts as a solvent ;
yet Professor Ramsey has calculated that if the
sulphates of lime and soda, and the chlorides of
sodium and magnesium, and the other mineral in.
gradients 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 in vibible 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
intermittant, so that ten 'or twenty years should
elapse between the peri.-Als 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 obj et of comparison with the intermittant
outpourings of a ♦olcano. Dr. Daubeny, after de-
voting a month to the analysis of the Bath waters,
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 net 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 EOM° 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 tied 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, wi

continue to rank,ms heretofore, as the most influentia
causes of such movements. The temperature of the
Bath waters varies in the different springs from 11'7
deg. to 120 deg. Fahrenheit. Tnis, 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—viz., 135 deg.
Fahrenheit—but they ate situated within 40 miles
of those cones and lava streams of the Eire' which,
though they may have spent their force ages before
the earliest records of history, belong neverthelss
to the most 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 Fracce and Germany were the theatres
of frequent convulsione, we may well suppose that
Eogtand was often more rudely shaken than now
—and such shocks as that of October,last, 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 tuns the deoxidation of
atmospheric air carried down by rain-water, we
may imagine the supply of this water to be fare
nished by some mountainous region, possibly a disc
tent 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 gypsons
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 ehowa
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 watere, and has dis-
covered in them three metals which they were not
previons:y known to cantain—namely, copper,
strontium, and lithium ; but he has searched in vain
fa cap dam 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-
trum analysis. Professor Bunsen, of Heidelberg,
led the way in 1860, in the application of this new
test to the hot waters of Badereßaden and of Dark-
heim in the Pal itir ate. He observed is the spectram
some coloured lines of which he coald not inter'ret
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 ..hree millions. He named
the first cte )um, from the bluish-grey lines which
it presented in the spectrum ; and the second rubi-
dium, from iTs two red lines. Since these successful
experiments was made, thallium, to called from its