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been periodically subject. The Aux, from the hoemorrhoids, which has been stopped, particularly, in the cold season, bas conftantly been brought on by this regimen, after fix days perseverance in it; and sometimes,' even on the third or fourthday. He relates likewise a few out of many instances, which he could produce, of the good effects that have enfued from the fame regimen, in Sweden; where the process of impregnating water with fixed air, &c. is become familiar in families of all ranks: and he affirms, that the most obftinate intermittent fevers' which raged throughout that whole kingdom, for some years paft, and which would not yield to the bark, have almolt conItantly been removed by the artificial Seltzer water, or other similar impregnations of water with fixed air,

Differtation II. On the Analysis of I'uters. · This valuable paper contains, within a imall compass, a most excellent fet of observation's and rules for examining waters; or for discovering, collecting, and ascertaining the nature of their various and heterogeneous contents.

Besides the usual methods, and those which have been fuggefted by the numerous discoveries that have been very lately made in the chemical branch of experimental philosophy; it contains many others peculiar, we believe, to the Author. Such, we apprehend, is his method of detecting the presence of fulphur, in certain waters of the fatid kind, by adding a small quantity of concentrated nitrous acid; by which the fatid smell is corrected, and finally. deftroyed, and the fulplour is precipitated. We Hall only mention another new and curious test, by which the presence of calcareous earth in water is detected.

This test is the acid of sugar, discovered, we believe, by the Author, and of which we ihall have occasion to speak presently.. If the smallest portion of calcareous earth, combined in any manner whatever, be contained, even in a very large quantity of water [ Cantharo' *), a small cryftal of this acid, no larger than the head of a pin, being dropped into it, will produce fria and clouds; caused by a precipitate formed of the calcareous earth, combined with the faccharine acid, and which is insoluble in water. Scarce any water, the Author observes, is' perfectly free from calcareous earth. Even with respect to that which is reputed the purest, this teft is so fenfible, that when the water has stood twenty-four hours after it has been dropped' into it, it will present some appearance, though perhaps a faint one, of this peculiar precipitate." A combination of the faccharine acid; with an alcaline salt, produces the same effect, still more sensibly, in consequence of a double affinity. No acid;

The Swedilha Canibarus, as we are told in a noté, conats of eight quadrantes; each of which contains 12, cubic Swedish inches.


alcaline, or earthy body, whatever, is capable of decompounding the compound thus formed of the faccharine acid, and calcarous earth Differtations III. and IV. On the Waters at Upsal: and on the

Acidulous Waters in the Parish of Danemarks, These two articles, independent of the immediate or local purposes for which they were drawn up, furnih useful exemplifications and illustrations of the rules contained in the preceding differtation,

Dissertation V. On Sea Water.... Dr. Sparrman, who joined Dr. Forster in the last expedition to the South Seas, brought home with him, and gave to the Author for his examination, several glass bottles filled with sea water, drawn up from very great depths, in the latitude of the Canary Iflands. We shall not take any further notice of this Analysis, than just to observe, that the water was perfe&ly inodorous, and though not grateful to the taste, it did not excite a naufea, like that which is taken from the surface of the sea.

M. Bergman accounts for this last circumstance, by observing, that the immense number of fishes who die in the sea, rise up to the surface, in consequence of the inflation attending pucre fac-. tion; so that the water, at great depths, is not contaminated by them. When there is a scarcity of water, in a ship, he chinks: much fresh water might be faxed, by boiling the ship's victuals in an equal quantity of this purer, sea water. Differtation Vic On the Metbød of imitating the Cold medicated ada

Waters. :) By the cold medicated waters, the Author means those whose saline, metallic, or earthy ingredients, are held in folution by fixed air; such as those of Pyrmont, Spa, Seltzer, &c. After giving an exact analysis of the contents of four of the principal of these natural waters; he teaches the method of preparing each of them by ært, or by fynthesis. From the late discoveries relative to this subject, no doubt can be entertained that art, in this one instance at least, is capable of excelling nature whatever the mayor and burgesles of Spa or Pyrmont may allege to the contrary. In this, and the following Differtation, the Author appears in the light of a good patriot as well as chemist : exhibiting, in a note, the fums paid by Sweden for the natural waters imported into that kingdom in 1773 and 1774 ; which, may now be laved, by subftituting the artificial waters in their place. We shall not dwell on this subject, but thall attend to the next dissertation, which contains matters less known. Differtation VII. On the Method of imitating the Het medicated

Waters. It appears extremely singular to us, that the curious process described in this differtation, by which the warm or fulphurcoys,


waters, such as those of Aix-la-Chapelle, &c. are perfectly imitated, thould have been so long overlooked : at least, this is the first notice that we have received of it. It confifts fimply in adding the vitriolic acid to hepar fulphuris, and impregnating water with the peculiar species of air that arises from this mixture; in the fame manner as when water is impregnated with the fixed air, arising from the mixture of that or any other acid with chalk. This hepatic air t, as the Author calls it, is very readily absorbed by water ; to which it gives the smell, taste, and all the other fenfible qualities of the fulphureous waters. A Swedish cantharus of distilled water, will absorb about fixty cubic inches of this hepatic air; and 'on dropping into it the nitrous acid, as we have mentioned under the second differtation, it will appear, that a real fulphurris contained, in a state of perfect solution, in this water, to the quantity of eight grains. It does not appear that any other acid, except what the Author calls the Dephlogisticated Marine Acid, will produce this effect. -When any particular fulphureous water is to be imitated, we scarce need to observe, that the saline, or other contents peculiar to it, are to be added to the artificial hepatic water!" Instead of the liver of sulphur, the operator may use a mixture of three-parts of filings of iron, and two-parts of fulphur melted together f.

il may perhaps be thought that water thus prepared does not differ from that in which a portion of the hepar sulphuris has been dissolved: but to us it appears evidently to differ from 'it in this material circumstance; that in the solution of hepar fulphuris, the sulphur is held in solution by the water, through the means of the alcali combined with it: whereas, in M. Bergman's process, it does not appear probable that the bepar fulphufis rises substantially, in the form of air; for, in that case, its presence in the hepatic water might be detected by means of the weakest of the acids (even the mephitic), which would precipitate te sulphur 'from-it. Nor can it be supposed that any por tion, or conftituent part, of the alcali ittelf (except' a part of: its remaining fixed air) can come over. The water therefore must owe its impregnation to the fulphur, raised, in some pecu-Jiar-manner; into the state of an elastic vapour; permanent, when the experiment is made in quicksilver; but condensible in water, and rendered soluble in that fluid through the means of fome unknotun principle combined with it, and which the Au-' tor fuppofes' to be the matter of heat, combined with it through the medium of phlogifion.

t Part of this air, as we have found, is fixed air, proceeding, from the salt of tartar.

I In this case, there appears to us, to be very little absorption : thë beparic air, or vapour, fceming to be diffolved, or solpended in infiammable air.

In our account of Dr. Priestley's last volume of Experiments, &c. {M. R. June 1779, p. 4+4&c.] we took notice of one of the ways, indicated by one of his experiments, by which the fulphur is produced that is found in the vaults and aqueducts at Aix la Chapelle. The present process not only clearly explains the manner in which these waters become impregnated with fulphur ; but likewise the cause of the appearance of the crude: fulphur above mentioned. It appears, from the Author's experiments, that air, as well as the nitrous acid, has the property of decompounding this water:--even that small quantity of atmoSpherical air, that is contained in common water, has this qua. Tity in a sufficiently fenfible degree, when the latter is employed in the process, instead of fresh diftilled water, or water that has been lately boiled.

When the natural fulphureous waters, therefore, come in contact with the external air;, the latter, according to the Author, seizes the phlogistic principle which kept the fulphur diffolved in the water; and thus, in time, are formed chofe fulphureous crujls, which, as well as even the prefence of actual sulphur in these waters, have been the subjects on so much controversy among the chemists.

Differtation VIII. On the Acid of. Sugar. In this ingenious Differtation, M. Bergman communicates, the discovery of a netu acid:: the method of producing its and its chemical properties and affinities with respect to various other fubftances. The process for procuring it is briefly this: To one qunce of the finest sugar are added three ounces of the strongesti spirit of nitre, in a tubulated retort. After the most phlogisticated part of the nitrous acid has exhaled, a receiver is to be adapted to the neck of the retort, and the folution made to boik gently, till it acquires a brown or chesnut-colours when three more ounces of nitrous acid are to be added, and the ebullition is to be continued till the tinged and smoking acid has nearly disappeared. The liquor remaining in the retort is now to be put into a broad vessel; and, on cooling, quadrilateral prismaa tic crystals will be formed, which, after being dried on a bibusi Jous paper, will weigh about a drachm and 1 and 19 grains.

The remaining liquor, in which the crystals were formed, is to be treated in the same manner, with two ounces more of fpirit of nitre; and will furnish half a drachm and 13 grains of fresh crystals. To the glutinous fluid, now remaining, two more ounces of nitrous acid are to be added in Imall portions; at different times; and the whole is to be evaporated to drynels: when a faline mafs is left, which, when dry, weighs about half a drachm. These different products mixed together are purified by repeated solution and cryftallisation.

The crystals thus procured are the acid of sugar;-ché laft, discovered, and the dearest of the acids ; for io produce cna


ounce of it (from three, ounces of sugar) thirty ounces of strong fpirit of nitre must be employed. Sugar, however, is not the only substance from which it is co be procured. It may be extracted not only from honey, and other faccharine juices, but likewise from gum arabic, and even the most highly rectificd Spirit of wine.

M. Bergman relates, in detail, the various combinations of this new acid with faline, earthy, and metallic substances. From a combination of it with spiric of wine; he procured a kind of ether; inferior, however, to the vitriolic and other æthers in inflammability. The fixity and strength of this acid are very considerable; so that, as we have indeed already hinted, it ex. pels even the vitriolic acid from gypsum and selenite. On being exposed to heat in clofe velleis, the water of its cryftallifation is firit partly expelled; and a great part of the falt is fublimed in a purer state: a very great quantity of air, or elastic vapour rifing during the distillation. From half an ounce of the crystals, near ico cubic inch:s of air were produced; half of which confifted of fixed air, capable of being absorbed by line water ; in the other portion, a candle burned, and with a blue flame.

Considering the large quantity of spirit of nitre employed in producing this acid; it might be suspected that it is only a modification of that acid; especially as the Author has not yet been able to procure it by any other means; such as simple difillation, detonation with nitre, digestion and decoction with the vitriolic, and dephlogisticated marine acids, &c. It is certain, however, that it has properties not only different from, but likewise contrary to those of the nitrous acid; which, in most cases, it expels from its bases. Besides, it is allowed that sugar, as an essential salt, contains an acid ; though enveloped in, and combined with, various faponaceous and phlogistic matters. M. Bergman's idea is, that the nitrous acid, in consequence of the peculiar avidity with which it combines with phlogiston, breaks the union of these matters with the faccharine acid, and leaves the latter disengaged. Be this as it may, the discovery of an acid, differing in its qualities so much as this does from the nitrous and other acids, is certainly no small acquisition to the art of chemistry.

We have extended this article to such a length that, at prefent at least, we shall only obferve, that there remain three other differtations, which, like the former, exhibit many-proofs of the chemical skill, genids, and industry of the Author. These are, Differ. IX. On Alum, ånd its Preparation : Differ. X. On 'the Combinations of Antimeny. with Tartar, and the Tartareuus Aud: and D fler. Xi. On Magnesia. In a lare foreign publication, we have seen with pleasure a second volume of this collection of DIL, sertations advertised, as being then in the preis, of which, when it appears, we faali sot fail to give an account.


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