Short memoirs for the natural experimental history of mineral waters addressed by way of letter to a friend / by Robert Boyle.

Notes on the Twenty sixth Title.

XXVI. 1. Divers wayes may be propounded to discover which of the Qualities, mention'd in this Arti∣cle, is predominant in the Salt to be examin'd; but I confess I somewhat doubt, whether these waies of Tryal be so certain, as many will be forward to think them. 2. If Acidity be guess'd to be predominant in the Salt propos'd it will probably appear by such waies as these. By the Tast, odour, or both: By working upon Coral or Crabs eyes finely powder'd: By curdling of Milk; By making Syrup of violets reddish: By the power of destroying the blew colour of the Infusion of Lignum Nephriticum: By not being Precipita∣ble by Potent Acid Liquors as Oyl of Vitriol, Spirit of Salt; and by being Precipitable by Oyl of Tartar per de∣liquium, as also by strong Spirit of Urine, and other volatile Alcaly's, as they are call'd. But, as I was noting above, I doubt whether these proofs be

absolutely certain; for, if I mistake not, I found some Purging Mineral Waters that would not give even so slight a proof of acidity, as to destroy the blewness of the Nephritic Tin∣cture: Which yet would curdle Milk, and turn it to a kind of Posset; and, on the contrary, I found that some Ger∣man Spaw Water would not curdle Milk, & yet would readily deprive the newly mention'd Tincture of its ce∣ruleous colour; which yet I did not find that some of our English Fer∣ruginous Waters were, at least when brought me to London, able to do. 3. The predominancy of an Alcaly, in the Salt of a Mineral Water, may be probably discover'd by such waies as these. By the Lixiviate Tast, Smell, or both; the former of which may be observ'd in the true Niter of the Ancients, (which I have had brought me from Aegypt, and a neighbouring Country, whose name I do not now remember:) By the turning of Sy∣rup of violets green: By the Precipi∣tation

of solution of sublimate made in Spring-Water: By an effervescence or conflict with some potent Acid, as Aqua fortis, or well dephlegm'd Sp∣rit of Salt: By heightning the red Tincture of Logwood or Brazil, drawn with common Water, to which, may be added a Nicer way or two that I have elsewhere mention'd. But I propose these waies but as ap∣pearing rational, upon the score of my having successfully try'd them with other Saline Bodies that were Alca∣lisate. For as to those Mineral Wa∣ters, I have had occasion to examine, I do not remember I have yet met with any, wherein an Alcaly was pre∣dominant. 4. But perhaps farther Inquiry will discover to others here in England, what I have not yet met with: And I doubt not but that there are, in divers places of the Earth, Salts of an Alcalisate nature. And I pre∣sume that, if the Egyptians were any thing curious of such things, they would find, among their Springs or Wells, divers Waters impregnated

with them. For I found by Tryals, purposely made upon Latron, as some knowing men call the true Egyptian Niter, presented me by an inquisitive Ambassador who came out of the East, that the native Salt exhibited di∣vers of the same Phaenomena that other factitious Alcali's do. And some Salt, afforded by the famous Waters of Bourbon in France, being brought me thence, with a desire that I would examine it, I found it to be evidently Alcalisate; insomuch that it would make a conflict with Acids, and pre∣sently turn Syrup of violets green. 5. If we suspect Vitriol to be much predominant in the Saline part of a Mineral Water, we may endeavour to discover it by such wayes as these. By its blackning a Solution of Galls: By its vomitive operation upon the Drinkers, thô this may sometimes be an uncertain way especially because an invisible permixture of Arsenic, or or perhaps Arsenical Fumes, may give the Water they impregnate an Emetic Quality: By putting Alcali's

to a strong solution of the suppos'd Vitriol, and observing whether it will afford a yellow or yellowish Precipi∣tate, if Salt of Tartar or Spirit of Urine be dropt into it. By taking notice, whether a Sulphureous Spirit, espe∣cially▪ such an one as I formerly told I had made thô not here describ'd, will make a blackish or a very dark colour with it, as I first guess'd, and then found it would do with several vitriolate Liquors, and even with one, to make which we had dissolv'd but one grain of a Natural Vitriolate sub∣stance in above four or five thousand times its weight of Syrup or Water. But in the parts about London I re∣member not that, in any of the Waters I have made Tryals on, I have found Vitriol to be predominant, or to be so much as a manifest Ingredient: Which seem'd to me the more re∣markable, because several parts about this City are not destitute of Marca∣sites, the Parents or Wombs of Vitriol. Since the writing of these Papers, being casually visited by a discerning

Stranger, who had a particular occa∣sion to take notice of the Residences of many of the Mineral Waters of France, his native Country; he an∣swer'd me that he never met with any that was manifestly Vitriolate; and he seem'd to be of opinion, that no Vi∣triolate Spring had yet been disco∣ver'd, among the many Mineral ones that are known to be in that Country. 7. Since we so rarely meet with either manifestly Acid, or evidently Alcalisate, Salts in our English Mine∣ral Waters, it may deserve a serious Inquiry, what other Salts they may be impregnated with; and especially from what Salts, the Purgative ver∣tue, that is found to belong to many of them, as Epsom, Barnet, Acton, &c. do's proceed? Common Salt indeed, as is already noted, I have found to∣kens of in the German Spaw Water; and in all the English Mineral Waters, I had occasion to try, not one that I remember excepted. But I did not find that common Salt was so copi∣ous in any of them, as to disclose it

self by Chrystallizing in Cubical grains. And the way, I made use of, to examine the Saltness of the Water without Crystallization, is not equal∣ly certain in all sorts of them. And because I had not store enough of these Liquors, to evaporate them in large quantities, thô I could not discern, in the clear Salts they afforded, either Vitriol, or Salt Peter, or Allom, or even common Salt, by their peculiar and genuine Figures; yet I dare not confidently say, that none of our Eng∣lish Mineral Springs abounds with any of those Salts. But as far as I can guess, by the Tryals that I have hitherto had opportunity to make, I am apt to think that the Salt, that is found in our Purgative Waters, and and in some of them copiously e∣nough, dos not belong to any one known sort of Salts, but is either of a sort, for which as for many other Minerals, we have yet no name: or, which seems more probable, is a Salt of a compounded Nature, made up by the coalitions of some or all of

the Salts above mention'd, and per∣haps of some other, as yet nameless, Subterraneal Salt that the Spring inssolves in its passage, That two Bodies, which are neither of them Cathartic, may, by a change of Tex∣ture, wrought in one another, com∣pose a third Body, that is briskly purgative, I have shewn in another Paper. Besides having formerly had occasion, in order to the resolution of a certain doubt I had entertain'd, to burn Salt of Tartar with about a double weight of common Sulphur, I thence obtain'd, as I expected, a Neutral Salt, that had peculiar Qua∣lities differing from those of the Bo∣dies imploy'd to make it up: And talking of this Salt with an ingenious Empyrick, he told me it had a Qua∣lity I had not mention'd, and that a very useful one, since in the dose of half a dram, or in some Bodies, being taken in Wine or Broth, it would con∣siderably, and yet gently and without gripings, purge. And without the help of Salt of Tartar have sometimes

made out of common Sulphur, a Chrystalline Salt of a somewhat Vi∣triolate Tast, the like to which might possibly be made under ground, where there are Subterraneal fires, tho per∣haps not observed nor suspected, since we made this Salt without adding any thing to the Sulphur, on∣ly by the help of Fire and common Water. And I remember that a great Virtuoso, several years ago, brought me, in order to an Examen he desir'd I should make of it, a certain Salt af∣forded by a Spring in or near his land, which I remember was in the West of England, tho I have forgot the name of the County: Which Salt no Body knew what to make of, but I quickly told him, I took it to be of the na∣ture of the Sal mirabile Glauberi, and predicted that in such Tryals it would afford such and such Phaenomena, which accordingly came to pass. And I thought that, if opportunity had not been wanting this Salt would have appear'd Purgative, as some factitious Salts that resemble it in

transparency, colourlesness, and Fi∣gure have been observ'd to be.