31. The same solution, being mixed with syrup of violets, became of a
reddish colour.
32. Saccharum Saturni being added to the solution, precipitated a thick
lactescent cloud.
33. Ol. tart. p.d. being also added to this solution, it caused no
visible effervescence, yet raised some bubbles of air, and caused a
coagulation of many small brown terrene nubeculæ in the water; which,
after standing some time, subsided to the bottom, and left the water
clear.
These experiments do plainly evince, that this water contains an
aluminous salt, conjoined with a fine terrene substance, which is
probably a part of the matrix, from whence the salt has been formed.
This salt gives no signs of any alkaline principle; but, on the
contrary, of an acidity, as its solution reddens with syrup of violets.
With this salt there are also intimately conjoined some very subtile
chalybeat parts, which are not separable from it by elixation or
evaporation.
Alum is distinguishable from all other mineral salts, by liquifying
and bubbling upon a red-hot iron, and turning into a white calx. But
this could not be well expected from this aluminous salt, which we
had extracted from the water, because it was extremely foul, by being
combined with so large a proportion of earth; which earthy parts were
the occasion of turning the salt of a blackish colour upon the iron.
However, we see it turns white by a further degree of heat. But if the
salt had been dissolved, filtrated, and crystallized, till it had been
purified and freed from this terrene matter, it would then certainly
have had the same appearance upon the red-hot iron, as a pure aluminous
salt. Again, as it is peculiar to an aluminous salt to liquify in some
degree with fire, so we see, that this was evidently the case of this
salt. Its eliquation indeed could not be so remarkable, as in pure
alum, because of its being mixed with so much earth; but that it did
liquify in some degree is plain, because the whole mass of salt and
earth, even when reduced to a powder, ran all together like a cinder.
The experiment upon the solution of this salt with ol. tart. p.d.
is also a further proof of what we have already asserted: for tho’
there was no visible effervescence, yet the bubbles of air shew, that
there was an intestine conflict of the oil with the acid principle
in the solution; which being absorbed by the alkali, the earth was
precipitated, to which it formerly adhered.
The two next experiments were made in order to discover, whether an
acid or alkaline principle prevailed in the water.
_Exp._ 34. Forty gutts of the syrup of violets being added to an ounce
of the water, the mixture became of a bright sea-green colour.
35. A quantity of water being kept boiling for five minutes, and
afterwards allowed to stand till it became clear, was carefully
filtrated from its ochrous sediment: after which, upon its mixture with
syrup of violets, it turned of a faint reddish colour.
From these experiments we infer, that this mineral water contains
both an alkaline and an acid principle; the former consisting of the
ochrous and ferrugineous parts, which are separated from the water by
elixation; and the latter of the aluminous salt, which remains in the
water after elixation.
The following trials were made in order to know what effects are
produced in the water by being exposed to the air; and in what respects
the waters of the two springs differed from each other.
_Exp._ 37. An English quart of the water of each of the springs being
fully exposed to the air in two China bowls, the next day that of the
under spring was neither altered in its taste, colour, or transparency,
nor in any other shape whatever; but that of the upper spring appeared
of a yellowish colour, altho’ it was clear and transparent as the other.
On the second day the taste of the waters scarcely appeared to be any
way diminished. No sensible change could be observed in the lower
water; but the upper water was become more yellow than it was the day
before, yet without any loss of its transparency. They both tinged of a
deep blue colour with galls; which tinctures appeared equally deep and
strong, as they did before the waters were exposed to the air.
The third day the lower water appeared clear and colourless as before,
only its surface was covered with a few small spots of cremor. The
upper water appeared more yellowish than formerly, and its surface
was almost wholly covered over with the cremor. They both afforded a
tincture with galls, which was not sensibly different from what they
gave before their exposure.
On the fourteenth day the water of the under well had precipitated
a yellow ochrous sediment, but the other water a more considerable
quantity. A large quantity of cremor continued also to swim upon the
surface of the upper water, but there was very little separated from
the water of the under well. Both waters being now tried with galls,
instead of the deep blue colour, which they did formerly exhibit, they
now became only of a deep purple colour.
On the twentieth day the visible appearance of both waters was the same
as when last observed.
On the thirty-eighth day they both afforded as deep a purple colour
with galls, as they did three weeks before; and during that time also
they had not precipitated any more of their ochrous parts, nor suffered
any other sensible alteration.
The water of the upper well being filtrated from all the ferrugineous
matter, which it had separated during these thirty-eight days, was
rendered almost as limpid and clear as when newly taken from the
well: but, being boiled for some time, it became of a turbid yellow
colour; and being allowed to stand, it again precipitated abundance
of an ochrous sediment; and being filtrated, and mixed with galls, it
received a faint purple colour of a blueish hue.
38. A bottle of the water of each of these springs, being carefully
sealed, carried to Moffat, and kept for two months, suffered not the
least alteration during that time, but was as fresh as when immediately
taken from the fountain. And I am informed, that after it is carried
to Edinburgh, and to places at a greater distance, it will keep a much
longer time without being any way spoiled.
I believe it will appear from these observations, that this mineral
water continues longer intire, and particularly that it retains the
quality of tinging with galls longer, than most others of the chalybeat
kind: at least, of a great number, which I have seen described, I do
not remember one, that retains it near so long, when exposed to the
open air. Many of them lose this quality intirely in a few hours; and
it is greatly impaired in the same time, even in those which retain
it longest. But this water, we see, remains exposed to the open air
for days, without almost any alteration. This may perhaps be owing
either to the larger proportion of ferrugineous parts, with which it is
impregnated; to their being attenuated to a greater degree; or to their
more perfect commixture with the water, by means of the aluminous salt.
The longer time, that any mineral water does remain intire, without
any separation of its mineral parts; or the longer it retains the same
form, which it has when newly taken from the spring; the more perfect
is the commixture of these parts with their fluid vehicle: and I
believe, upon that account, will be more effectual for medicinal uses:
for which reason, I suppose, these waters may prove a more beneficial
medicine, than any others of the ferrugineous kind, whose mineral
contents are not so intimately commixed with the aqueous fluid.
As these waters are so long in separating their mineral contents, they
appear particularly well adapted for being transported to distant
places: for by this quality they are fitted to undergo a long carriage,
and to be kept a considerable time, without any diminution of their
medicinal virtues. It must also be noticed, that the water of the under
well is by much the best of the two for carriage, or for being long
kept, as it is longer in separating its mineral contents than the upper
one.
From these experiments it is evident, that there is a considerable
difference betwixt the waters of the two springs. The upper one
contains a much larger quantity of ochrous earth, and metalline cremor,
than the under one; which is the reason, why it yields a deeper colour
with galls, as may be observed in the first experiment. I suspected,
on the other hand, that the under water contained a greater proportion
of alum, than the water of the upper spring; but this I cannot affirm,
as I find I had neglected to make the experiment, which would have
determined whether it be so or not. Tho’ the mineral contents of these
two waters be similar, yet, if they be thus mixed in them in different
proportions, this must certainly create a difference between them,
which deserves to be attended to, as it may be sufficient to disallow
of their being used promiscuously, since their medicinal effects may be
thereby different.
But now, to sum up the evidence, which these experiments, taken all
together, do afford, concerning the mineral ingredients of this Spaw; I
think they determine, with some degree of certainty, that it contains
two different principles of iron, both of which are fixed. The one,
which is the ochrous earth, is a true _minera ferri_, and, altho’ it
be a crude mineral, exists in the water in a very fine and subtile
form; the other, which is the cremor or pellicle, whose parts are
also extremely attenuated in the water, appears to be iron, not in
its mineral, but in its metalline form, and, when thrown up upon the
surface of the water, shews itself like an extreme thin _lamina_ of
that metal. There seems also to be some small proportion of sulphur
joined with the metalline cremor. The other mineral ingredient, which
enters into the composition of this Spaw, is a considerable proportion
of an aluminous salt, which is conjoined with a small quantity of a
light brown-coloured earth (probably a part of the matrix whence the
salt is formed), and still more intimately connected with some of the
chalybeat parts of the water, which are not separable from it either
by elixation or evaporation. Whether these be saline or terrestrial, I
cannot determine.
Having thus endeavoured to discover, by some plain and simple
experiments, the mineral principles, with which this medicinal water
is impregnated; I shall now only add some observations, with respect
to the origin of steel waters, and particularly of this Spaw, whose
origin, I think, is thereby discovered and ascertained in a very
obvious manner.
Among several things, that are still deficient in the history of
mineral waters; an exact knowlege of their origin seems to be the
chief; that is, from what fossils, and in what manner, these waters do
acquire the mineral substances, with which they are impregnated. As
this happens in the bowels of the earth, and is therefore far removed
from our view, it is not surprising, that there has been so little
discovered concerning it; tho’ indeed there have been many elaborate
hypotheses framed in order to account for it.
The writers on mineral waters have been of very different and opposite
opinions concerning their origin. They have disagreed widely amongst
themselves; and I very much suspect, that the accounts, which most of
them give of this matter, are not agreeable to truth: particularly
with respect to chalybeat waters, I have seen none, who have given a
satisfactory account of their origin. They have all agreed, that iron,
or the vitriol of that metal, does exist in mineral waters; but they
have never yet agreed, how they came to exist in them, or in what
manner mineral waters come to be imbued with these fossils.
Some of the more ancient writers cannot comprehend, how simple water
should be intimately impregnated with so many different kinds of
minerals, except by the means of some powerful agent. And as they
thought nothing more proper for communicating and mixing mineral
substances with water, than violent heat, they therefore termed all
mineral waters, of whatever kind, by the name of _thermæ_. They saw
some spring from the earth extremely hot, others moderately hot, others
tepid, others excessively cold: they concluded from this, that all
such various degrees of heat in these waters were owing either to the
different degree of subterranean fire, which they had undergone; or
else to the great distance, which some of them had run in the earth,
after they had been sufficiently heated. They therefore maintained,
that those waters particularly termed _acidulæ_ (the greatest part of
which are impregnated with iron), or those, which, tho’ intensely cold,
contained a large proportion of mineral matter, had in some part of the
earth been impregnated with it, by means of an intense heat, which they
had been gradually deprived of by a long passage thro’ the colder parts
of the earth.
Some naturalists again, of a later date, having exploded the former
notion as chimerical, have thought, that a vapour rising from vitriolic
minerals, and mixed with the neighbouring streams of water in the
bowels of the earth, has imbued them with some of the parts, and with
the properties, of vitriol.
Others are of opinion, that the exhalations of vitriolic minerals,
passing thro’ the cavities of the earth, are there condensed by the
subterraneous cold into a limpid fluid, containing the very finest
parts of that mineral salt: which fluid, mixing with the præterlabent
streams of water, and issuing out of the earth with them, produce those
mineral springs called vitriolic.
The last opinion I shall mention on this subject, and which indeed
appears the most plausible, is of those, who think, that the iron is
corroded and dissolved in these waters by means of an acid: for, as
they imagine simple water incapable of doing this, they suppose, that
it is first imbued with an acid in the bowels of the earth; and then,
by the corrosion of the chalybeat minerals, thro’ which it runs, it
comes to be impregnated with them. I once received this opinion, as
the most probable I could then observe, concerning the origin of these
springs: yet not as being satisfactory; for there are many objections
against it, which it is difficult either to elude or to answer.
The supposition of an acidity in ferrugineous waters, I thought but
ill confirmed, because, upon trial, they discover no vestiges of it,
but rather appear to be alkaline. Besides, in considering the causes
of mineral waters, it seems more probable, that whatever minerals they
contain, they must be such, as can be received or extracted by common
water in its passage thro’ the earth, by solution, abrasion, or the
like simple operations; and in this way alone I think we may come to
account not only for the commixtion of the saline and terrene minerals,
which are found in medical waters, but likewise of those, that are
metalline or sulphureous; for which simple water, at first sight, may
perhaps seem to be an insufficient solvent.
It was this notion, that first induced me to make trial upon various
mineral and metallic bodies, in order to know how far they could
communicate their virtues to common water by infusion. I thought this
might throw some light upon the origin of mineral waters; yet, tho’
I made a great many experiments of this sort, and particularly upon
several kinds of native chalybeat minerals, I was as little satisfied
concerning their origin as before. I at length, however, met, by
accident, with what I had inquired after with so little success.
As I happened to be at a gentleman’s house near Edinburgh, in whose
estate there was a great deal of coal, and who was at that time working
a level or adit, in order to drain off the water, I observed, that
the current of water, which flowed from this level, separated a great
quantity of ochre, and, emptying itself into a river soon after it came
from the entry of the level, tinged all the stones and the channel of
the river, for a good way, of an ochrous colour. The taste of this
water was exactly like that of a common steel Spaw; and it afforded a
purple colour with galls[55]. As I knew, that this water flowed off a
great body of coal, I often infused that fossil, taken from the pits
near this level, in common water; but the infusions never yielded any
tincture with galls. I tried in the same way another mineral, that
the miners call _blaes_; which is a cliffery stratum of a blueish
colour, that often lies both above and below the coal: also another
fossil of a brown colour, which is very ponderous, and is called by
the miners _dogger_; a thin seam of which often lies in the midst of
the coal. However, neither of these would afford an infusion, that
would tinge with galls. At last I got another mineral out of these
coal-pits, which is sometimes found amongst the coal, but is not so
frequent as any of the former; and this fully answered my expectation.
It is found either in round or broad pieces, is exceeding ponderous,
and of a shining yellow colour, and is called by the miners _brass
lumps_. When I infused this mineral for a short time in common water,
it communicated to it all the properties of a steel Spaw; its taste
was exactly the same; and it received a tincture from galls, which was
of a more diluted or intense purple, according to the proportion of
the mineral added to the water, or to the time of the infusion. This
simple experiment does therefore clearly discover to us the origin of
steel waters, and the manner, in which they are impregnated with their
mineral contents in the bowels of the earth.
This observation, which I had made concerning the origin of steel
waters, led me, when I first visited Hartfell-Spaw, to inquire into the
adjacent fossils: which was the more easily done, as the strata of the
earth about the well, for a considerable depth, are exposed to view.
After some search among these, I found a stratum of cliffery rock,
about three or four feet thick, of a grey colour, and, I think, about
twenty paces from the spring. In some of the hollow places of this
rock, where the rain and wind did not reach, I observed a white saline
efflorescence on its surface, which when I had taken off and tasted, I
concluded, from its styptic and chalybeat taste, that it was a native
vitriolum Martis, notwithstanding its white colour; but I found it,
upon trial, to be alum, having some fine attenuated parts of iron
conjoined with it, and the same salt with that contained in the Spaw
water.
Having taken some pieces of this rock, which were quite free from
the saline effervescence, and infused them in common spring-water
for some hours, this water did thereby acquire the true taste of the
Hartfell-Spaw. It likewise in the same manner received a deep blue
tincture with galls, and contained all the other qualities of that
mineral water, without the least difference, that I could observe:
which, I think, ascertains the true origin of this mineral spring in
the most obvious and undeniable manner.
I am persuaded, that this plain and easy method of investigating the
origin of mineral springs is not only superior to the most learned
discussions and elaborate theories, but will be found to be the surest,
yea, the only way of extending and compleating our knowlege concerning
them. As I have not yet had the opportunity of making the experiments,
which I designed, upon the two fossils, that we find to be the cause
of the above mineral waters, and which will be necessary to elucidate
and compleat these observations, which we have made concerning their
origin; I shall now only add one thing, and recommend it to the
observation of others: “_Whether or not, from such a knowlege of the
origin of mineral waters, we may not acquire artificial ones of as
great, or perhaps of greater, medicinal use, than those, which are
naturally produced?_”
XVIII. _An Account of the State of the Thermometer at the_ Hague _on
the 9th of_ January 1757. _Extracted from a Letter of Mr._ Abraham
Trembley, _F.R.S to_ Tho. Birch, _D.D. Secret. R.S._
[Read Mar. 3, 1757.]
Hague, Febr. 15. 1757.
I Carefully observed the thermometer during the cold days, which we
have had this winter. I made use of the same thermometer, with which
I made my observations in 1740, and for that purpose fixed it in the
same place, where it was that year, _viz._ in a window directly exposed
to the north, and open to a large square. In 1740 I saw Fahrenheit’s
thermometer at two degrees below 0. This year, on the 9th day of
January in the morning, it was at three degrees above 0; that is, only
five degrees higher than in 1740.
XIX. _Experimental Examination of_ Platina. _By_ William Lewis, _M.B.
F.R.S._
[Read Mar. 17, 1757.]