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222 S A L T S P R IN G S .
only 1 *50 of salt. I was told that there is
a deep and nearly inaccessible chasm in the
rock behind the springs, which is supposed
to have some connection with them. Beside
common salt, the water contains in
small proportions, sulphat of lime, sulphat
of soda, and sulphat and muriate of magnesia,
together with oxyd of iron. Much
of the gypsum in this part of the Tarentaise
being intermixed with rock salt, we may
well conceive whence the water derives its
saline impregnation ; but I am inclined to
believe that the high temperature of these
springs, as well as of all the thermal waters
in Savoy, is occasioned by an intermixture
of boiling water, which rises from immense
depths, being heated and forced up by
subterranean fife, like the hot springs in
countries undoubtedly volcanic. During
the great earthquake that destroyed Lisbon
in 1756, the salines at Moutiers ceased to
flow for forty-eight hours, and when they
flowed again, their quantity was increased,
but the saline impregnation was weaker. A
similar effect was produced at the same time
at the hot springs of Toplitz, in Bohemia.
It may seem extraordinary that the
waters at Moutiers, which have only half
S A L T S P R IN G S . 223
the strength of sea-water, should repay the
expence of evaporation ; but the process by
which it is effected is both simple and ingenious,
and might be introduced with great
advantage on many parts of our own coast,
should the salt duty be entirely removed.
The salt works at Bex, in the Pay de Vaud,
are nearly similar to those at Moutiers,
but not on so extensive a scale ; and a very
useful part of the process at Moutier is not
adopted at Bex. Having never seen an
intelligible account of the process of evaporation
by faggots, I shall endeavour to
give such a description as will enable any
person to imitate it in this country ; indeed,
so little is known of this mode of evaporation
by faggots, that it has been often
stated by English writers, and has recently
been again gravely repeated, that it
consisted in throwing salt water upon burning
faggots, and gathering the salt that remained.
This would be a mode of making
salt, as wise and practicable, as the nursery
method of catching birds by putting salt
on their tails.
It is obvious that water so weakly impregnated
with salt as to contain only one
pound and a half in every thirteen gallons.
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