Philosophical transactions, Vol. L. Part I. For the year 1757. / Giving some account of the present undertakings, studies, and labours, of the ingenious, in many considerable parts of the world.

by Various; Royal Society

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.

Hague, Febr. 15. 1757.

Read Mar. 3, 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.