been periodically fubject. The flux, from the haemorrhoids, which has been stopped, particularly, in the cold season, has conftantly been brought on by this regimen, after fix days perfeverance in it; and fometimes, even on the third or fourthday. He relates likewife a few out of many inftances, which he could produce, of the good effects that have enfued from the fame regimen, in Sweden; where the procefs of impregnating water with fixed air, &c. is become familiar in families of all ranks: and he affirms, that the moft obftinate intermittent fevers which raged throughout that whole kingdom, for fome years paft, and which would not yield to the bark, have almost conftantly been removed by the artificial Seltzer water, or other fimilar impregnations of water with fixed air.

Differtation II. On the Analysis of Waters.

This valuable paper contains, within a mall compass, a most excellent fet of obfervations and rules for examining waters; or for difcovering, collecting, and afcertaining the nature of Befides the ufual their various and heterogeneous contents.

methods, and those which have been fuggefted by the numerous difcoveries that have been very lately made in the chemical" branch of experimental philofophy; it contains many others peculiar, we believe, to the Author. Such, we apprehend, is his method of detecting the prefence of fulphur, in certain waters of the foetid kind, by adding a small quantity of con-centrated nitrous acid; by which the foetid fmell is corrected, and finally deftroyed, and the fulphur is precipitated. We fhall only mention another new and curious teft, by which the prefence of calcareous earth in water is detected.

This teft is the acid of fugar, difcovered, we believe, by the Author, and of which we thall 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 fmall cryftal of this acid, no larger than the head of a pin, being dropped into it, will produce ftria and clouds; caufed by a precipitate formed of the calcareous earth, combined with the faccharine acid, and which is infoluble in water. Scarce any water, the Author observes, is perfectly free from calcareous earth. Even with respect to that which is reputed the pureft, this teft is fo fenfible, that when' the water has stood twenty-four hours after it has been dropped into it, it will prefent fome appearance, though perhaps a faint one, of this peculiar precipitate. A combination of the faccha-' rine acid, with an alcaline falt, produces the fame effect, still more fenfibly, in confequence of a double affinity. No acid,

The Swedith Cantharus, as we are told in a noté, confifts of eight quadranter; each of which contains 12 cubic Swedish inches.

alcaline,

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alcaline, or earthy body whatever, is capable of decompound-' ing the compound thus formed of the faccharine acid, and calcarous earth

Differtations III. and IV. On the Waters at Upfal: 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, furnish useful exemplifications and illuftrations of the rules contained in the preceding. differtation

Differtation 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, feveral glass bottles filled with fea; water, drawn up from very great depths, in the latitude of the Canary Iflands. We fhall not take any further notice of this Analyfis, than just to obferve, that the water was perfectly in-. odorous, and though not grateful to the taste, it did not excite a naufea, like that which is taken from the furface of the fea.

M. Bergman accounts for this laft circumstance, by observing, that the immense number of fishes who die in the fea, rife up to the furface, in confequence of the inflation attending putrefaction; fo that the water, at great depths, is not contaminated by them. When there is a scarcity of water, in a fhip, he thinks much fresh water might be faxed, by boiling the hip's victuals in an equal quantity of this purer, fea water. Differtation VIe On the Method of imitating the Cold medicated Waters

By the cold medicated waters, the Author means those whofe faline, metallic, or earthy ingredients, are held in folution by' fixed air fuch as thofe of Pyrmont, Spa, Seltzer, &c. After giving an exact analysis of the contents of four of the principal of thefe natural waters; he teaches the method of preparing each of them by art, or by fynthefts From the late difcoveries relative to this fubject, no doubt can be entertained that art, in this one inftance at leaft, is capable of excelling nature. whatever the mayor and burgeffes of Spa or Pyrmont may allege, to the contrary, In this, and the following Diflertation, the; Author, appears in the light of a good patriot as well as chemift: 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 faved, by fubftituting the artificial waters in their place. We fhall not dwell on this fubject, but fhall attend to, the next differtation, which contains matters lefs known. Differtation VII. On the Method of imitating the Hot medicated Waters.

It appears extremely fingular to us, that the curious process defcribed in this differtation, by which the warm or fulphureous,

waters,

waters, fuch as thofe of Aix-la-Chapelle, &c. are perfectly imitated, fhould have been fo 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 fpecies of air that arifes from this mixture; in the fame manner as when water is impregnated with the fixed air, arifing from the mixture of that or any other acid with chalk. This hepatic air +, as the Author calls it, is very readily abforbed by water; to which it gives the smell, tafte, and all the other fenfible qualities of the fulphureous waters. A Swedish cantharus of diftilled water, will abforb about fixty. cubic inches of this hepatic air; and on dropping into it the nitrous acid, as we have mentioned under the fecond differtation, it will appear, that a real fulphuris contained, in a ftate of perfect folution, 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 fcarce need to obferve, that the faline, or other contents peculiar to it, are to be added to the artificial hepatic water Instead oft the liver of fulphur, the operator may ufe a mixture of three-parts of filings of iron, and two-parts of fulphur melted together .

It may perhaps be thought that water thus prepared does not differ from that in which a portion of the hepar fulphuris has been diffolved: but to us it appears evidently to differ from it in this material circumftance;that in the folution of hepar fulphuris, the fulphur is held in folution by the water, through the means of the alcali combined with it: whereas, in M. Bergman's procefs, it does not appear probable that the hepar fulphu Fis riles fubftantially, in the form of air; for, in that cafe, its prefence in the hepatic water might be detected by means of the weakeft of the acids (even the mephitic), which would precipitate the fulphur from it. Nor can it be fuppofed that any por rion, or conftituent part, of the alcali ittelf (except a part of: its remaining fixed air) can come over. The water therefore muft owe its impregnation to the fulphur, raised," in fome pecu-. liar manner, into the ftate of an elaftic vapour; permanent, when the experiment is made in quickfilver; but condenfible in water, and rendered foluble in that fluid through the means of fome unknown principle combined with it, and which the Author fuppofes to be the matter of heat, combined with it through the medium of phlogiston.

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Part of this air, as we have found, is fixed air, proceeding, fot. falt of tartar.

In this cafe, there appears to us, to be very little abforption the hepatic air, or vapour, feeming to be diffolved, or fufpended in inflammable air.

In our account of Dr. Priestley's laft volume of Experiments, &c. M. R. June 1779, P. 444, &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 prefent procefs not only clearly explains, the manner in which thefe waters become impregnated with ful phur, but likewife 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 quaItty in a fufficiently 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, feizes the phlogistic principle which kept the fulphur diffolved in the water; and thus, in time, are formed thofe fulphureous crufts, which, as well as even the pres fence of actual fulphur in thefe waters, have been the fubjects of fo much controverly among the chemifts..

Differtation VIII. On the Acid of Sugar.

In this ingenious Differtation, M. Bergman communicates the difcovery of a new acid; the method of producing it, and its chemical properties and affinities with respect to various other fubftances. The process for procuring it is briefly this: To one! aunce of the finest fugar are added three ounces of the strongest fpirit 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 boil gently, till it acquires a brown or chefnut-colour; 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 difappeared. The liquor remaining in the retort is now to be put into a broad veffel; and, on cooling, quadrilateral prifmatic crystals will be formed, which, after being dried on a bibus lous paper, will weigh about a drachm and and 19 grains.

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The remaining liquor, in which the cryftals were formed, is! to be treated in the fame manner, with two ounces more of fpirit of nitre; and will furnish half a drachm and 13 grains of fresh cryftals. To the glutinous fluid, now remaining, two more ounces of nitrous acid are to be added in small 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. Thefe different products mixed together are purified by repeated folution and cryftallifation.

The cryftals thus procured are the acid of fugar;-the laft difcovered, and the dearest of the acids; for to produce one

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ounce of it (from three, ounces of fugar) thirty ounces of ftrong fpirit of nitre must be employed. Sugar, however, is not the only fubftance from which it is to be procured. It may be extracted not only from honey, and other faccharine juices, but likewife from gum arabic, and even the most highly rectified Spirit of wine.

M. Bergman relates, in detail, the various combinations of this new acid with faline, earthy, and metallic fubftances. From a combination of it with fpirit of wine; he procured a kind of ether; inferior, however, to the vitriolic and other æthers in inflammability. The fixity and ftrength of this acid are very confiderable; fo that, as we have indeed already hinted, it expels even the vitriolic acid from gypfum and felenite. On being exposed to heat in clofe veffeis, the water of its cryftallifation is first partly expelled; and a great part of the falt is fublimed in a purer ftate: a very great quantity of air, or elaftic vapour rifing during the diftillation. From half an ounce of the cryftals, near 100 cubic inches of air were produced; half of which confifted of fixed air, capable of being abforbed by lime water; in the other portion, a candle burned, and with a blue flame.

Confidering the large quantity of fpirit of nitre employed in producing this acid; it might be fufpected that it is only a modification of that acid; efpecially as the Athor has not yet been able to procure it by any other means; fuch as fimple diftillation, detonation with nitre, digeftion and decoction with the vitriolic, and dephlogisticated marine acids, &c. It is certain, however, that it has properties not only different from, but likewife contrary to, thofe of the nitrous acid; which, in most cafes, it expels from its bafes. Befides, it is allowed that fugar, as an effential falt, contains an acid; though enveloped in, and combined with, various faponaceous and phlogistic matters. M. Bergman's idea is, that the nitrous acid, in confequence of the peculiar avidity with which it combines with phlogifton, breaks the union of thefe matters with the faccharine acid, and leaves the latter difengaged. Be this as it may, the difcovery of an acid, differing in its qualities fo much as this does from the nitrous and other acids, is certainly no small acquifition to the art of chemistry.

We have extended this article to fuch a length that, at pre fent at least, we shall only obferve, that there remain three other differtations, which, like the former, exhibit many-proofs of the chemical fkill, genids, and induftry of the Author. Thefe are, Differ. IX. On Alum, and its Preparation: Differ. X. On the Combinations of Antimony with Tartar, and the Tartarecus Acid: and Difler. XI. On Magnefia. In a late foreign publication, we have feen with pleafure a fecond volume of this collection of Dif fertations advertifed, as being then in the prefs, of which, when it appears, we shall not fail to give an account. MONTHLY