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ftance refembling fnow; which, as appears from experiments made with it, that we need not here repeat, evidently contains mercury and iron, in a faline form, intimately united with each other. Paffing the liquor through a filtre, this fnowy fubftance being left upon it, and there wafhed, and afterwards dried, prefents the appearance of a filver like mafs, made by the union of innumerable chryftals in the form of thin plates. It has no degree of acidity, and is perfectly free from acrimony.

It is very fingular that, on putting fome of this fnow-like falt (Sel Neigeux) into a folution of mineral alcali, though a brifk effervefcence is immediately excited, and the metallic falt undergoes fame change; yet it is not decompounded, but the liquor is ftill found to contain the combined metals, although the alcali fhould be made fenfibly to predominate. This fiagular phenomenon, which is not however an Unique, affords an exception to the established law of chemical affinities; as, in the prefent cafe, the acid will not quit either of the two metallic bodies with which it is united, though even a pure alcali is prefented to ita ftrong proof, as the Author obferves, of the intimate combination of the principles that conftitute this metallic falt.

The Author fuppofes that Keifar's celebrated pills are pro bably formed by a procefs not very different from that above given; if they really confift of a combination of mercury and iron with a vegetable acid, as was judged by the commiffaries of the Academy who analyfed them.

Though the Author had ufed many of thefe mercurio-martial preparations with fuccefs, in feveral chronic diforders; he was defirous of difcovering a mild but active preparation of mercury, in which it is not combined with acids; all of which, not excepting even the vegetable, render the compound too acrimonious, in particular cafes, or in fome delicate conftitutions. The latter part of this memoir contains an account of his fuccefs in discovering a method of rendering mercury foluble in water, without the affiance of an acid.

He was led to this difcovery, by reflecting that even gold was rendered foluble in water, by means of the liver of fulphur ; and did not doubt but that this powerful folvent would produce the fame effect on mercury, if the heat requifite for the completion of the procefs did not diffipate this volatile femi-metal. To avoid this inconvenience, he at first thought it neceffary to proceed by the Via humida, as it is called; mixing two drachms of the lixivium tartari with an equal quantity of the flowers of fulphur, in a mall matrafs placed in a fand bath. After boiling the ingredients fome time, and then adding water to them, he poured in two drachms of mercury. On agitating the mixture, the mercury was fpeedily, and almoft wholly, united with


the hepar into a black mafs; to which three or four ounces of water being added, and made to boil a few minutes, it was evident, from fubfequent experiments, that a fenfible portion of the mercury was taken up into the water, and retained in it, in a ftate of folution.

The Author afterwards fucceeded in forming a combination of the fame kind, in the dry way. He is of opinion that in thefe proceffes the mercury is combined with phlogilon; and that being likewife incorporated with the alcali, a faponaceous compound is formed, which has the property of rendering mercury foluble in water, in the fame manner as it does gold, and a variety of other fubftances. He recommends this milá mercurial preparation, as extremely penetrating, and well adapted to the cure of thofe diforders in which mercury is ufually employed; and has himself ufed it with confiderable fuccefs in various inveterate diforders of the fkin, as well as in the moft obftinate fcrophulous difcafes. He adds however no particulars concerning its dofe, or mode of operation. Memoir 111. Experiments on the Decompofition of vitriolated Tartar, by the Nitrous Acid alone. By M. Baumé.

Stahl's celebrated problem, in which he propofed to the che mifts to decompound vitriolated tartar, or to feparate the vitriolic acid from it fpeedily and in the palm of the hand, is here folved in a more fimple and unexpected manner, than by any of the procefles which had before been invented by Geoffroy and others; in which the folution of it was generally effected by means of a double elective attraction. The Author's experiments exhibit likewife a fingular and new exception to the common table of chemical affinities.

It is well known that the vitriolic acid fpeedily decompofes nitre; expelling its acid, and uniting with its fixed alcali, with which it forms vitriolated tartar. M. Baumé however has difcovered, and fhews in the prefent memoir, that if vitriolated tartar be diffolved in water, and fome spirit of nitre be added, the latter will in its turn diflodge the vitriolic acid, take poffeffion of the alcali with which it was united, and form with it a real nitre.

Other remarkable phenomena attend this experiment. If the veflel in which thefe fubftances are contained be expofed for a confiderable time to the open air, the nitre will in its turn be decompounded by the vitriolic acid remaining in the vessel, and which had before been expelled from the alcali by the nitrous acid. At the beginning of this decompofition the nitrous chryftals exhibit the appearance of many beautiful ramifications: the vitriolic acid rifes up through the capillary tubes of these branches, and at length takes entire poffeffion of the alcali: while the nitrous acid, thus difengaged, is, after a confiderable


time, almost entirely diffipated, in confequence of its volatility; leaving behind it a vitriolated tartar, capable of being again decompounded as before.

These are the most curious articles relating to chemistry, contained in this collection. The remaining papers are, Obfervations on the Chryftallifation of Neutral Salts, by M. Baumé: A minute and laborious Analysis of the Mineral Waters of Saint Remy,' by M. Marigues; and an account of fome experiments made by M. de Coffigni, relative to the method formerly propofed by Dr. Hales, of preventing the water provided for drinking on board of ships from becoming putrid, by adding to it a fmall quantity of the vitriolic acid.


The papers reducible to this clafs are, fome observations on the formation of Stalactites, in the neighbourhood of Rome, by the Abbé Mazeas; and three other memoirs containing various details relating to the natural history of the mineral waters at Montmorenci and Bagneres; and particularly a full account of some experiments, made at the latter place by M. Marcorelli, to ascertain the specific gravity and heat of the various sources of the baths.


In the fingle memoir which occurs relative to the first of these claffes, M. Gerard undertakes to diftinguish the different fpecies of the caucalis, which have hitherto been defcribed by botanifts with much ambiguity. In two fucceeding memoirs, M. le Prefident de Joubert defcribes a species of shell fish, called poulettes, lately discovered in the Mediterranean, which seem to be analagous to the foffil fhells defigned by naturalifts under the title of concha anomia.

Some curious particulars relating to the organs of hearing, in fishes, are contained in a following article; in which M. Camper not only fhews that fishes are endowed with this fenfation, but likewise describes the organs adapted to this purpose, in some particular species; illuftrating his anatomical defcription of them with three plates.

That water is at leaft capable of receiving and tranfmitting, to the animals contained in it, thofe peculiar impreffions that conftitute found, feems to have been completely evinced by the late Abbé Nollet, who dived under water on purpose in order to ascertain this fact, which had before been doubted of. account of the experiments which he made for this purpose may be feen in the Mem. de l'Acad. Année 1743, p. 279, Amfterdam edition.


A fubfequent memoir contains an account of an epidemical diforder, fatal among the dogs, in the year 1764, and of the obfervations made on diffection by M. Brafdor, at the com


mand of the Duke of Orleans, on those who died of this diftemper. In the greateft part of thofe which he diffected, one or more worms, fometimes three or four inches long, were found in the cavity of the noftrils. The Author confidering thefe infects as the probable caufe of the diforder, recommends the exhibition of injections and fumigations.

In the remaining memoir of this clafs, M. Muller defcribes with minuteness a non-defcript butterfly, and gives the history of its difcovery. We could almoft envy this fortunate naturalift the pleasurable emotions he appears to have felt on this event; to which he gives a certain degree of dignity by the air of circumstance and folemnity with which he relates it.

'Taking a walk,' fays he, on the 28th of June, to feek fome amusement in the productions of nature, I perceived a butterfly quietly fitting on a branch of the plant named epilobium montanum.'-But what butterfly can elude the discriminating ken of the fagacious hunter and collector, if it has the misfortune to differ from other butterflies? I feized it,' continues he, with precaution, and having no other method of fecuring it, I pierced it with a pin, and thus made an addition to my cellection of infects. Its wings gave me reafon to think that it was of a new species; but on returning home, and examining it more accurately, what was my furprise to find that it had no antennæ, &c.?'-In fhort, the happy discoverer of this butterfly proceeds to inform us, that its head differed from that of every other butterfly, and perfectly resembled that of a caterpillar.

During the space of a week,-for either through defign or accident, the pin had not touched any vital part of the anomalous ftraggler,-it layed feveral eggs, of a green colour, and then died-but in a virgin ftate, for time fhewed that thefe eggs had not been fecundated: accordingly, it may still remain problematical, whether the pfeudo-phalena, as it is here denominated, is an individual of a new and regular fpecies, or a monster; or whether this unique might not owe its uncommon head-piece, to its having neglected to leave its old head behind it, on its hafty transformation from the ftate of a chryfalis to that of a butterfly.


Of five obfervations prefented by M. Marcorelli, the first contains an account of an involuntary abftinence, during the fpace of eighteen days, fuftained by a young man who fell into a well, and had no other fuftenance than water. Among the fymptoms occafioned by this long abftinence, the principal and moft fingular was the total lofs of his understanding, which was not completely restored till fome time after his bodily health had been re-established.-The fecond contains the history of a fin


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gular tympany; and the third, that of a compound fracture of the arm. In the fourth, is related the cafe of a man who lived twelve years without being able to swallow the least particle of folid nourishment. On diffection, the diforder was found to have been caufed by a cartilaginous and nearly folid ring, which almost entirely ftopped up the paffage of the cofophagus. The fifth contains a fingularity found on the diffection of a body, in which two ureters were found on the right fide, perfectly distinct from each other, from their origin in the kidneys to their entrance into the bladder.


The two first articles, relating to this fubject, which occur in this volume, contain obfervations on a remarkable aurera borealis. In the first of them, M. Meffier makes a remark which, we believe, has hitherto efcaped the most attentive obfervers of this phenomenon. He declares, that the flashes which parted from the horizon, toward the latter part of the appearances here defcribed, were followed by a dull murmuring found. The calmness of the air, and the ftillness of the płace where he made the obfervation, as well as the particular attention that he paid to this circumftance, as foon as he firft perceived it, left him not the leaft room to doubt that the found proceeded from the flashes; and he could not compare it more aptly than to that which is produced by the effect of electricity;' by which we fuppofe he means that of the atmosphere, or thunder.

The third article contains a fet of meteorological obfervations, regularly kept at Pekin, by Father Amiot, a Jefuit, dur ing the space of fix years. On looking over this journal, we are furprised to find the cold fo much more intense and conftant at Pekin, during the winter, than it is with us; though that city is at leaft eleven degrees to the fouthward of London. In four years out of the fix, the thermometer has repeatedly funk to eight and even fix degrees, of Fahrenheit's fcale *. During feveral months he obferved the mercury to have been almoft conftantly below the freezing point. In one year, for inftance, we find only four days, in the interval between November and the end of the following March, in which the thermometer ever flood higher than that point; and on these days it rofe only four or five degrees above it.

None of the articles on thefe fubjects will admit of abridg-
Under the firft of thefe claffes are comprehended, two


The Author's obfervations are faid to have been made with a mercurial thermometer graduated according to Reaumur's fcale; but we have reduced the numbers to Fahrenheit's graduation.


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