whence the flone is extracted is not known: fome have faid it is taken from the bladder; and M. Prouft seems to have feen bezoars taken from the ignuana, a fpecies of edible lizard, which differs greatly from the bezears of the Pacos, or the Peruvian fheep. The laft letter contains an account of the change which happens to filver from a kind of ruft; it is of a violet hue, and is contracted by the air, but particularly that air which is derived from, or has been in contact with, living bodies. The calx is a fulphurated filver. In the neighbourhood of the volcanos in South America, where the hepatic odour is infupportable, and much fulphur is conftantly formed, horses are faid to fatten very quickly.

Dr. Hoepfner has found the ponderous fpar in a granite in Switzerland; and by this circumftance, completed the difcovery of the five primitive fimple earths in granite; and perhaps afcertained the true earthy nature of barytes. Dr. Girtanner confirms his former obfervations, and fhows that iron is really foluble in pure water, when it is not affected by the Pruffian alkali, till fome acid is added. The fame obfervation has, it 1eems, been made by the chevalier Landriani, and it is of great importance in the analyfis of mineral waters. Dr. Dolfufs has added a new muriatic oxygenated neutral to those described by Berthollet, by fhowing us how to combine the dephlogisticated fpirit of falt with magnefia. He calls it murias oxygenatus magnefiæ liquidus, because it cannot be obtained in a concrete form. Mr. Wiegleb's analysis of the green granite fhow's it to contain nearly equal proportions of flint, lime, and iron.

Phofphorus, Dr. Bonz tells us, is commonly black when mixed with a little of the acid; and he purifies it by boiling it with a little ammonia, and afterwards, two different times in fpirit of wine.-M. Adel informs us, that a pofthumous volume of Bergman's works is published, containing two analyfes of indigo, his treatife on geoponic earths, &c. M. Crell's mifcellaneous letter, which follows, we have formerly noticed.

M. Berthollet defcribes fome changes in the colours of aftringent vegetables, by the addition of iron, which depend on employing that metal in a state of calx, a circumftance indifpenfibly neceffary to the production of fome of the colours. We cannot now follow him particularly, but we purpose to refume the fubject when he performs his promife of continuing his en quiries; it is of great importance in the art of dying.

M. de Morveau's obfervations on the dilatability of the air and different gaffes are extremely valuable, fince in the more rigorous modern chemistry, the refults muft coincide with the ingredients, and the gaffes muit be meafured in many inftances, The degree of dilatability is an object alfo of greater importance, as it appears to follow no general rule: our author has examined the changes by the gradual increase of heat, and the refult is comprised in a table; but even this we have not room to trafffcribe, and it is of less confequence, fince it is published

by

M.

by Mr. Nicholfon in his excellent elementary treatise. Marquart's effays, of which fome account follows, we hope to notice more particularly. The volume concludes with an account of M. Gmelin's memoir on the combination of manganese with copper. Manganefe whitens copper, and M. Gmelin expects, from thefe trials, to be able to produce a white metal which will be elegant and ufeful.

Since four volumes of this work, which is in its nature temporary, and ought to have been examined as foon as they appeared, are already published, we must beg leave to extend this article a little farther, that we may, by diligence, compenfate for our delay, and that we may give more attention to the important articles, we fhall omit mentioning those which are more trivial, which we have, or fhall in future, notice. M. Coulumb's memoirs are of this kind; they have in part occurred in p. 217. of this volume, and the reft are in the volume of the French memoirs, now under our confideration.

M. Fourcroy, in his analyfis of a green ore of lead, tells us that it confifts in a great degree of arfenicated lead, and contains a little more than a quarter part of phosphorated lead, the reft is phofphorated iron and water. The baron Dietrich's work on the ftrata of minerals, &c. we shall return to as a feparate artiticle when the work is concluded.

M. Berthollet gives us the continuation of his experiments on the fulphureous (the phlogifticated vitriolic) acid; the for mer experiments may be found in the Memoirs of the Royal Academy for 1782. The acid, he obferves, is best phlogisticated by diftilling it from fugar; and when the neutrals are formed of the proper proportions, they are not deliquefcent as was reprefented in the former memoir. The vital air is not fo intimately combined in this phlogisticated acid as in the common fpirit of vitriol; and on this account, it is of ufe to deftroy fome colours; but its powers in this refpect are very limited, and are greater in its aeriform flate. The dephlogisticated, nitrous, and muriatic acid render filks and most animal fubftances yellow, a hue owing to the vital air. This the fulphureous acid destroys, a fact well known to the manufacturers in filk and in woollen, who use it in the ftate of gas. The dephlogifticated marine acid, in particular circumstances, feems to refemble the nitrous gas and fulphureous acid; this connection, firft pointed out in the Turin Tranfactions, is elucidated at fome length in the memoir before us, which is concluded by fome miscellaneous remarks on vital air, and its degrees of affinity in different proportions.

M. Chaptal in the next memoir describes the substances of which his pottery, manufactured at Montpelier, is made, with the varnifies. In all these refpects his works are greatly inferior to thofe of the English artifis, an inferiority which does not wholly depend on the imperfection of his materials. He manufactures a coarfe pottery and different chemical veffels. This

author's

author's obfervations on fome phenomena which occur in the combuftion of tulphur, are more important: he finds that, in proportion to the rapidity of the flame, flowers of fulphur, foft fulphur, fulphureous acid, and oil of vitriol are procured. The laft occurs only when the heat is very gentle, and the air has time to combine with the fulphur. The faltpetre ufually added to the fulphur, we perceive is not only of fervice in facilitating the combustion, but in furnishing the oxygen. Without this addition the acid is fulphureous, and in the fate of gas; with it, or, as we fufpect, with too great a proportion of it, a quantity of nitrous gas is formed, which corrodes the chamber, formed of, or lined with, lead. The calx in this way procured, is used as white lead. If M. Chaptal's is the most improved procefs employed in France, we are no longer furprised that the manufacture is now carried on to fo great an extent in this metropolis.

The influence of light on cryftallization is well known. M, Dorthes, in his confideration on the effects of light on different bodies, purfues the fubject farther. He found that light, thrown on one fide of a phial containing camphor, facilitated the cryftallization of the vapour. Other vapours appear to condense more eafily on the enlightened fide, and this attraction, our author thinks, draws the branches of confined vegetables towards the part where the light is admitted. The perfpiration of animals has the fame tendency, and animals which are colourlefs in their ufual fequeftered, winter, haunts, acquire fome colour as well as plants, when kept in the light.

M. Weftrumb's chemical analysis of the pretended cubic quartz, or the magnesio-calcareous borat, we mentioned in our account of Mr. Nicholfon's work, when the time of our being able to examine thefe volumes was uncertain and at a diftance. We may now add, that M. Hyer, in a different tract, confirms the refult.

M. Weftrumb, in his new experiments on crude fal ammoniac (the ammoniacal muriat) and on magnefia, fhows that it is neither an alkali or calcareous earth, which mixed, or accidentally united with mild magnefia, decompofes the ammoniacal muriat, for that it is alone capable of producing this effect, as well as the calcined magnefia, if the quantity of pure earth employed in the decompofition be double that of the acid in the neutral. On the contrary, mild volatile alkali will decompofe the muriat of magnefia; and in general, this alkali will precipitate magnefia from its folutions, while the earth is foon again diffolved, and alkaline air efcapes. The muriat of magnelia is very cauftic, fo that the acid is in a very concentrated state in this composition, and it is not easily feparated by heat alone; yet if feparated while fome fubftance capable of combining with it were in the receiver, we might obt in new products hitherto undifcovered, or probably find out its radical.

The properties of the dephlogisticated muriatic acid have been already employed in the bleaching of cloths and threads.

A de

A defcription of the process is given by M. Berthollet, with an account of fome other properties of this fluid. This process is a most important improvement in the arts; and it is, we find, practifed with fuccefs in many manufactories in Great Britain. The oxygenated acid is employed in a fluid state; for in that of gas it does not act equably or regularly: it is, however, impoffi ble to abridge our author's defcription, or the steps which led him to the most improved method. It is not one of the least advantages, that the natron which remains from the process will greatly leffen the expence of it. This part of the process, we apprehend, is not generally known; and we could with that for this purpose it were poffible to remit the duty on falt. Bleaching in this manner would then be fo common and fo advantageous, as to fupply barilla in a great degree for the other manufactories. This peculiar acid is alfo employed to deffroy the red ground of figured linens. After linens are ftamped, the colours do not fully appear till they are dipped in a folution of madder, which, uniting with the other dyes, forms the beautiful figures obferved on the printed linens and cottons. This dye must be afterwards deftroyed. When united with an alkali, the oxygenated acid brightens the red colour of the cottons imported from the Levant : it blanches also the yellow wax, and, in a great degree, the green vegetable wax. This fluid may be employed to judge of the durability of colours; and in any cloth, the application of the dephlogifticated acid, followed by immerfion in a diluted vitriolic acid, will deftroy every colour.

Another analysis of a green ore of lead, confifting in a great measure of phofphorated lead, by M. de Fourcroy, is fubjoined, and an account of a memoir by the fame author, on the recipro cal action of metallic calces and volatile alkali follows. In the fulmination of gold and filver, it is now well known that there is a mutual decompofition of the alkali and the calx. M. Fourcroy enquires into the refult of a fimilar union with manganefe, mercury, iron, and other metallic fubftances. The three me. tals mentioned, decompose the alkali and recover fome of their phlogiston; in other words, lofe fome of their vital air. Li tharge and fal ammoniac decompofe each other only in part. Arfenic, the molybdenic and tungflenic acids, feem to lose the portion of oxygen which they poffeffed, and return to the flate of calces. Zinc, antimony, bifmuth, and cobalt, were found unalterable, the caufe of which is to be explained in another memoir.

M. Van Marum writes to M. Berthollet, that fixed air, prepared with the greatest care, fo as to be perfectly dry, when electrified by Teyler's great machine, produced inflammable air, a proof of its containing water. We cannot enlarge on this experiment, but if the electrical fluid did not decompofe the conducting iron, or the mercury which confined the air, the aerial acid, with its affiftance, probably produced this effect. In fact, it seems a very inconclufive trial.

M. de Fourcroy has furniflied a memoir on the precipitation

of Epfom falt, by the three mild alkalis; and on the properties of aerated magnefia cryftallifed. He finds that aerated alkali will not precipitate magnefia, though it feparates this earth, becaufe the air diffolves it again; and that the alkali is in too great proportion when added in equal parts. If the aerated magnelia feparated without precipitation be fuffered to remain, it will cryftallife; but the cryitals are not pure. This is lefs confpicuous with the foda, not because it contains lefs air, but because the vitriolic acid attracts it more powerfully from this alkali; with the ammonia the precipitation is not procured without long. boiling, and the air efcapes in great quantities. In a high de gree of heat, vitriolic ammoniac will, in turn, decompofe aerated magnefia, on account of the volatility of the alkali and the air. The properties of cryftallifed magnelia are not of importance, and from its nature are fufficiently obvious.

This volume concludes with mifcellaneous extracts from the fecond volume of M. Crell. We may fhortly mention, that a defcription and plate are to be published of the great mine of falt-petre, which has been vifited by M. M. Zimmerman and Hawkins it is found at Molfeta, near the Adriatic fea. The falt found in the Alps is, we are told by M. Morel, a native foda, mixed with a fulphurated foda, a fulphurated magnefia, and a very beautiful fluor fpar: all thefe are marks of the Alps being once covered by the fea. M. Heyer complains that no ufe has been made of the property which the falt of wood-forrel has to precipitate magnefia; and he wishes that it fhould be enquired, why alum is fometimes precipitated like a gum, refembling precipitates of flint, as it forms a jelly which acids attack with difficulty. The crystals which form in the extract of the aconitus napellus, after a long keeping, feem to M. Thuten phosphorated lime.

FOREIGN LITERARY INTELLIGENCE.

IN

N returning to the foreign communications on natural hiftory, which we have for a long time neglected, it will be convenient and useful to confider, firft, what has been faid relating to the more perfect animals, and to continue the feries down to the mineral kingdom, through a chain varying only by fhades in its different links; though the difcoveries will not be fo numerous as to enable us to proceed with very much regularity and uniformity. Whether the human race really form one ipecies, varied only by climate, cuftoms, or incidental cir cumftances, we need not now enquire. In ftating the facts on this fubject, we have hefitated, and felt it difficult to decide. M. Arthaud feems convinced that the black inhabitants which extend on the coast of Africa, from 18° north latitude to 18o fouth, are of a different fpecies from Europeans, or even the inhabitants of the interior parts, which he obferves, from the teitimony of M. Vatable, are as fair as Europeans. He admite

that