XVII. An Account of a new medicinal Well, lately discovered near Moffat, in Annandale, in the County of Dumfries. By Mr. John Walker, of Borgue-House, near Kirkudbright, in Scotland.
Read Feb. 10, & Mar. 3, 1757.
THIS mineral spring was found out by one Mr Williamson, a few years ago, when he was overseeing a mine, which was at that time carrying on in its neighbourhood. It is situate about four miles distant from Moffat, in the bottom of a deep scar, which is on the west side of a large mountain called Hartfell, from which it has acquired the name of Hartfell-spaw. This scar is a part of the mountain, thro' which a small stream of water has worn its way to a considerable depth; by which it has laid open, and exposed to view, the strata of the earth on each side: and in the bottom of this scar, and near to the brink of this small brook, the mineral water springs up.
When I saw it, it consisted of two springs, which were very well ordered by Mr. Williamson, so as to run from two wooden spouts, immediately at their rise out of the earth; which indeed must be of very great advantage to all mineral waters; and I am persuaded there are many, whose medical qualities are greatly impaired by falling into reservoirs, and continuing in them for some time after they spring from the earth. The one of these springs was situate about ten or twelve yards farther up the brook than the other; and they were then distinguished by the names of the upper and lower spring: but I have been since informed, that their situation is now altered. Each of these springs did at that time run nearly the same quantity of water, which, as I thought, was above an English quart in a minute, and that during a season of very dry weather.
As there are many instances of mineral waters springing out of the earth very near each other, which at the same time are impregnated with very different principles; it therefore seemed not at all improbable, that as these waters did appear to run, for some part of their course, in different channels, they might in some respects be different from each other. And this suspicion I found not to be altogether groundless with regard to these springs, as will be shewn afterwards. For which reason it may be observed, that the following trials were all made upon the water of the upper fountain, except where the other is particularly mentioned; and also that they were made within 24 hours after the water was taken from the spring, being carried to Moffat in bottles carefully sealed.
According to what may be inferred from the following experiments, it may be premised, that this water appears to contain in it a large proportion of iron, but in two different forms; and an aluminous salt, which is conjoined with a terrestrial principle.
As the contents of several mineral waters have been the cause of many different opinions, and of great disputes among physicians and chymists; as the inquiry I made into the principles of these waters, which I am now considering, was not performed with that nicety and exactness I could have wished; and as I am persuaded, that to dogmatize in any branch of philosophy can never tend to its advancement; I shall not therefore pretend to determine with certainty in any part of this subject, where the contrary opinion can be admitted with the least degree of probability. These trials are indeed but few and imperfect, and are no-way sufficient to form an exact account of this mineral water; yet I believe they may afford some conclusions, which may be serviceable in compiling a more compleat history of it. They render it pretty evident, that the above-mentioned principles are contained in these waters: and tho' I will not pretend absolutely to exclude all others, yet I must say, that, by what inquiry I made, I could not observe them to be in the least impregnated with any other kind of mineral substance.
After a good deal of observation upon the water of this Spaw; and after many fruitless attempts, which I have at different times made upon several other waters of the chalybeat kind in Scotland, in quest of the volatile spirit, which has been commonly attributed to them; I must own, that I have been induced to think, that there is no such thing exists in these waters at all. What has been generally called the spirit of steel waters, seems to me to be very unintelligible; altho' the existence of it in these waters has been asserted by all the writers on this subject, which I have yet had occasion to see. The spirit of a mixed body is commonly taken to be a subtile, penetrating, light, and volatile substance, more susceptible of motion than any other of its parts, and most easily separable from them by avolation. But that any chalybeat water contains such a substance, I think has never been made evident, unless where the water has been found to be impregnated with some other mineral principles. Some steel waters, I believe, contain a large proportion of air, whose elasticity may occasion it to break forth with an explosive force; some others there are, which contain a volatile and sulphureous halitus; and to one or other of these two causes, or to some other mineral principle, I think most of the phænomena may be referred, which have been attributed to a ferrugineous or vitriolic volatile spirit.
As the first thing observable in a mineral water is its outward form, we must therefore take notice, that the water of this Spaw equals the clearest spring-water in transparency; and is likewise as free of any colour or odour: yet its taste is very strong, and may be discerned to be compounded of a sweet, subacid, and astringent taste. Its sweetness and acidity appear sensibly to arise from alum; and its high styptic and astringent taste does as evidently proceed from that mineral salt, joined with some earthy or ferrugineous parts. I must likewise observe, that when I first compared the taste of these two springs, I could plainly discern, that the water of the lower spring was more acid, and less astringent, than that of the upper one; and, on the contrary, the water of the upper spring seemed more astringent, and less acid. This induced me to think, that the mineral parts, which caused the acid and astringent tastes, were mixed in the waters of these two springs in different proportions. And what I observed of them afterwards still confirmed this conjecture.