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whence the stone is extracted is not kpowu : fome have said it is taken from the bladder; and M. Proust seems to have seen bezoars taken from the ignuana, a species of edible lizard, which differs greatly from the bezoars of the Pacos, or the Peruvian heep. The last 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 sulphurated filver, in the neighbourhood of the volcanos in Şouth America, where the hepatic odour is infupportable, and much fulphur is constantly formed, horses are said to fatten very quickly.

Dr. Hoepfner has found the ponderous spar in a granite in Switzerland; and by this circumstance, coinpleted the discovery of the five primitive fimple earths in granite; and perhaps ascertained the true earthy nature of barytes. Dr. Girtanner confirms his former observations, and shows that iron is really foluble in pure water, when it is not affected by the Prussian al. kali, till Tome acid is added. The same observation has, it Seemns, been made by the chevalier Landriani, and it is of great importance in the analylis of mineral waters. Dr. Dolfuls, has added a new muriatic oxygenated neutral to those described by Berthollet, by showing us how to combine the dephlogisticated fpirit of salt with magnesia. He calls it murias oxygenatus magnesize liquidus, because it cannot be obtained in a concrete form. Mr. Wiegleb's analysis of the green granite show's it to contain nearly equal proportions of flint, lime, and iron.

Phosphorus, 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 spirit of wine.-M. Adel informs us, that a posthumous volume of Bergman's works is published, containing two analyses of indigo, his treatise on geoponic earths, &c. M. Crell's mifcellaneous letter, which follows, we have formerly noticed.

M. Berthollet describes some changes in the colours of astringent vegetables,, by the addition of iron, which depend on employing that metal in a state of calx, a circumstance indispenfi. bly necessary to the production of some of the colours.". We cannot now follow him particularly, but we purpose to resume the subject when be performs his promise of continuing his en quiries; it is of great importance in the art of dying.

M. de Morveau's observations on the dilatability of the air and different gasses are extremely valuable, since in the more rigorous modern chemistry, the results must coincide with the ingredients, and the gasles must be measured in many instances, The degree of dilatability is an object also 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 resule is comprised in a table ; but even this we have not room ko tradicribe, and it is of less consequence, since it is publifed

by by Mr. Nicholson in his excellent elementary treatise. M. Marquare's effays, of which fome account followe, we hope to notice more particularly. The volume concludes with an account of M. Gmelin's memoir on the combination of manganese with copper. Manganese whiteos copper, and M. Gmelin ex. pects, from these trials, to be able to produce a white metal which will be elegant and useful.

Since four volumes of this work, which is in its nature tem, porary, and ought to have been examined as soon as they appeared, are alrcady published, we must beg leave to extend this article a little farther, that we may, by diligence, compensate for our delay, and that we may give more attention to the important articles, we shall omit mentioning those which are more trivial, which we have, or shall in future, notice. M. Coulumb's memoirs are of this kind; they have in part occurred in p. 217. of this volume, and the rest are in the volume of the French memoirs, wow under our consideration.

M. Fourcroy, in his analysis of a green ore of lead, tells us that it confitts in a great degree of arsenicated lead, and contains a little more than a quarter part of phosphorated lead, the rest is phosphorated iron and water. The baron Die rich's work on the strata of minerals, &c. we shall return to as a separate artiticle when the work is concluded.

M. Berthollet gives us the continuation of his experiments on the fulphureous (the phlogisticated vitriolic) acid; the for. mer experiments may be found in the Memoirs of the Royal Academy for 1782. The acid, . he observes, is best phlogistiçated by distilling it from sugar; and when the neutrals are formed of the proper proportions, they are not deliquescent as was represented in the former memoir. The vital air is not so intimately combined in this phlogistii ated acid as in the common spirit of vitriol; and on this account, it is of use to destroy some colours; but its powers in this respect are very limited, and are greater in its aeriform flate. The dephlogisticated, nitrous, and muriatic acid render filks and most animal substances 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 state of gas. The dephlogisticated marine acid, in particular circumstances, seems to resemble the nitrous gas and lulphureous acid; this connection, first pointed out in the Turin Tranfa&tions, is elucidated at some length in the me moir besore us, which is concluded by fome miscellaneous remarks on vital air, and its degrees of affinity in different proportions.

M. Chapral in the next memoir describes the substances of which his pottery, manufactured at Montpelier, is made, with the varnities. In all these refpects his works are greatly inferior to those of the English artilis, an inferiority which does not wholly depend on the imperfection of his materials. He manufactures a coarse pottery and different chemical vessels. This


author's observations on some phenoinena which occur in the combustion of fulphur, are more imporiant: he finds that, in proportion to the rapidity of the flame, flowers of sulphur, soft Tulphur, sulphureous acid, and oil of vitriol are procured. The last occurs only when the heat is very gentle, and the air has time to combine with the fulphur. The faltpetre usually added to the sulphur, we perceive is not only of service in facilitating the combullion, but in furnishing the oxygen. Without this ad. dition the acid is fulphureous, and in the fate of gas; with it, or, as we suspect, with too great a proportion of it, a quantity of nitrous gas is formed, which corrodes the chamber, formed of, or lined with, Icad. The calx in this way procured, is used as white lead. If M. Chaptal's is the most improved process employed in France, we are no longer surprised that the manufacture is now carried on to so great an extent in this metropolis.

The influence of light on cryfallization is well known. M. Dorthes, in his consideration on the effects of light on different bodies, pursues the subject farther. He found that light, thrown on one lide of a phial containing camphor, facilitated the crystal. lization of the vapour. Other vapours appear to condense more easily on the enlightened side, and this attraction, our author thinks, draws the branches of confined vegetables towards the part where the light is admitted. The perspiration of animals has the same tendency, and animals which are colourless in their usual sequcftered, winter, haunts, acquire some colour as well as plants, when kept in the light.

M. Weftrumb's chemical analysis of the pretended cubic quartz, or the magnego.calcareous borát, we mentioned in our account of Mr. Nicholson's work, when the time of our being able to examine these volumes was uncertain and at a distance. We may now add, that M. Hyer, in a different tract, confirms the result.

M. Weftrumb, in his new experiments on crude fal ammoniac (the ammoniacal muriat) and on magnesia, shows that it is neither an alkali or calcareous earth, which mixed, or accidentally united with mild magnefia, decomposes the ammoniacal inuriar, for that it is alone capable of producing this effect, as well as the calcined magnesia, if the quantity of pure earth employed in the decompofition be double that of ihe acid in the neutral. On the contrary, mild volatile alkali will decompose the muriat of magnetia ; ard in general, this alkali will preci. pitate magnesia from its solutions, while the earth is soon again diffolved, and alkaline air escapes. The muriat of magnetia is very caustic, so that the acid is in a very concentrated state in this compotition, and it is not calily separated by heat alone; yet if separated while some fubftance capable of combining with it were in the receiver, we might obtiin new products hitherto undiscovered, 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, aith ani account of some other properties of this Huid. This process is a most important improvement in the arts; and it is, we find, praétised with success 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, impoffible 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 proces will greatly lefsen 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 possible to remit the duty on salt. Bleaching in this manner would then be so common and so advantageous, as to supply barilla in a great degree for the other manufactories. This peculiar acid is also employed to destroy the red ground of figured linens. After linens are Itamped, the colours do not fully appear till they are dipped in a solution of madder, which, uniting with the other dyes, forms the beauti. ful figures observed on the printed linens and cottons. This dye must be afterwards destroyed. 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 irax. This fluid may be employed to judge of the durability of colours; and in any cloth, the application of the dephlogisticated acid, followed by immerfion in a diluted vitriolic acid, will destroy every colour.

Another analysis of a green ore of lead, consisting in a great Measure of phosphorated lead, by M. de Fourcroy, is subjoined, and an account of a memoir by the same author, on the reciprocal 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 decomposition of the alkali and the calx. M. Fourcroy enquires into the result of a similar union with manganese, mercury, iron, and other metallic substances. The thiee me. tals mentioned, de compose the alkali and recover fome of their phlogiston; in other words, lose some of their vital air. Lie tharge and sal ammoniac decompose each other only in part. Arsenic, the molybdenic and tungfenic acids, seem to lose the portion of oxygen which they poffefred, and return to the fate of calces. Zinc, antimony, bismuth, and cobalt, were found unalterable, the cause of which is to be explained in another memoir.

M. Van Maram writes to M. Berthollet, that fixed air, prepared with the greatest care, so as to be perfectly dry, when eletrified by Teyler's great machine, produced 'intiam nable air, a proof of its containing water. We cannot enlarge on this experiment, but if the electrical fluid did not decompose the conducting iron, or the mercury which confined the air, the aerial acid, with its atlistance, probably produced this effect. 'In fact, it seems a very inconclufive trial. M. de Fourcroy has furnified a memoir on the precipitation

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ot Epom salt, by the three mild alkalis ; and on the properties of aerated magnesia crystallised. He finds that aerated alkali will not precipitate magnesia, though it separates this earth, because the air dissolves it again ; and that the alkali is in too great a proportion when added in equal parts. If the aerated magnelia separated without precipitation be suffered to remain, it will cryftallise; but the cryitals are not pure. This is less conspicua ous with the soda, nor because it contains less air, but because the vicriolic acid attracts it more powerfully from this alkali; with the ammonia the precipitation is not procured without long boiling, and the air escapes in great quantities. In a high degree of heat, vitriolic ammoniac will, in turn, decompose aerated miaynesia, on account of the volatility of the alkali and the air. The properties of cryftallised magncia are not of importance, and from its nature are fufficientiy obvious.

This volume concludes with miscellaneous extracts from the second volume of M. Crell. We may shortly mention, that a description and plare are to be published of the great mine of salt-petre, which has been visited by M. M. Zimmerman and Hawkins : it is found at Molfeta, near the Adriatic fea. The falc found in the Alps is, we are told by M. Morel, a native soda, mixed with a fulphurated foda, a fulphurated magnesia, and a very beautiful fluor fpar: all these are marks of the Alps being once covered by the sea. M. Heyer complains that no use has been made of the property which the fall of wood-forrel has to precipitate magnesia; and he wishes that it should be enquired, why alum is sometimes precipitated like a gum, resembling precipitates of flint, as it forms a jelly which acids attack with diffi. cully. The crystals which form in the extract of the aconitus napellus, after a long keeping, seem to M. Thuten phosphorated lime.

IN returning to the foreign communications on natural hi-

story, which we have for a long time neglected, it will be convenient and useful to confider, first, what has been said relating to the more perfect animals, and to continue the series down to the mineral kingdom, through a chain varying only by shades in its different links; though the discoveries will not be so 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, customs, or incidental cir. cumliances, we need not now enquire. In ftating the facts on this subject, we have hesitated, and felt it difficult to decide. M. Arthaud seems convinced that the black inhabitants which extend on the coast of Africa, from 18° north latitude to 18% fouth, are of a different fpecies from Europeans, or even the ipbabitants of the interior parts, which he observes, from the testimony of M, Vatable, are as fair as Europeans. He admite


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