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whiteness. Tartar and common salt may be added, if a linie more polish is required. This is nearly the substance of here memoirs, which we have fritered into chemical queitions, leit we might injure ingenious artists who now live by thcie proceffes. We have given nothing which can, we think, materially hurt-them, though to the chemilts we have said enough,

What was formerly called the Siberian spar was fome rime fince found to be a mineral of lead. It riles near Catherineburg, at Beresof, where there are also mines of iron containing gold, which is separated from the cutical pyrite, by reducing the iron to a hepatised flate. The crystals of the red lead are rhomboidal tetraedra, like the white and green ores, but lighter, and losing about a quarter part of their weight when weighed in water. M. M. Marquart and Lehman have examined it in the moist way, and by means of the blow-pipe, as well as in the open air. The resule of M. Marquart's examination is, that it contains 36 parts of lead, 37 of vital air, 24 of iron, and 2 of alum. The little addisional weight seems to have arisen from the product having acquired some moisture. The alum M. Lehman calls selenite.

M. Sage has also described an earthy ore of lead combined with arsenic and phosphoric acid : its crystals are prismatic hexaedra ; the colour of a yellow green; but this is not owing to any other metal different from the lead. The arsenic is. in the proportion of about half, and the lead in about one tenth.

M. Hyelin has given a very scientific description of his method of reducing molybdena. It has been doubted in France, whether this was really a metal, or an carth distinguished by peculiar appearances, in consequence of its union with the vi. triolic acid. Our author has shown how to separate the acid, by repeatedly pouring olive oil over it, and burning them toge. ther, which changes the acid into a fulphur, and diffipates it in vapour. He shows also how to reduce the molybdena, by uniring it with other metals, whole volatility and inflammability are in this way increased, and by different fluxes, which produced the regulus described by Scheele and Bergman. These details we cannot easily abridge: when melted alone or with powdered cbarcoal, and the inass is afterwards triturated, the Imall particles seemed to thow fome brilliancy, but did not apo pear to be decidedly metallic.

As we proceed in a retrograde course, we fhall next mention the earths so far as relates to their chemical history, or their artificial decompofition by heat and moifture. M. Sage has added fome farther observations on the fappare, a stone whose composition we defcribed from M. Sauffure's analysis, in our lait volume, p. 383. M. Sage has described it in the second volume of his Analyse Chymique, P: 71. in the following terms. In the granites of Spain, and in those of St. Symphorien, near Lyons, we meet with a kind of an aigce marine, of a Klue colour, in long flattened tetraedal prisms, foliated in a longi. tudinal direction, and sometimes united in bundles. He afierwards received, he tells us, some of these foliated berils from mount St. Gothard. They are found in a white transparent quartz moulded on the crystals. They are also met with on white opaque felt spar, mixed with teatite: sometimes the quarız, and felt spar are coloured by ocre. The berils, from different countries, nearly resemble each other: in a group of crystals from Germany, a rhomboid was very distinguishable. 'The softnefs, described by M. Sauflure, is only in the direction of the lamellæ ; in a contrary one it strikes fire with iteel, when the crystals are not exfoliated, or the laminæ divided by steatite. Ii does not lore this property by calcination; and the surface, in consequence of the heat only, becomes of a pearly whiteness. The colouring iron may be extracted, we find, by powdering the stone and distilling it with eight parts of fal am. moniac, which sublimes without decomposing, and the lixivium of this falt-work, with the phlogisticated alkali, deposits Prusfian blue. M. Sage, we perceive, continues to think the ting. ing principle of Pruilian blue an acid, and the neutrals formed by ir, kept in his possession some years, are not, he observes in another memoir, deliquescent. Our author suspects that the magnesia which M. de Saussure found, came from the steatite.

blue

A new felt spar, styled the adularia, has been discovered on the Stella, near St. Gothard, by M. Spini. Of this family we were only acquainted with the common felt spar, the La. brador stone, and the picrre de lune. The adularia is, like the other species, foliated ; its fracture rhomboidal; its fragments rhomboids, four surfaces of which reflect the light, though the four other furfaces have not this property. Its colour (that of mother of pearl) diftinguishes it from the common feli ipar. it is cat's-eyed sometimes, like the Labrador ftone, but the colours have not the same brilliancy or intenfity, and seem owing to fome oblique imperceptiblc tiffures, such as occur in glass alternately exposed to the rain and to the sun, when it is beginning to exfoliate. Belides, the Labrador ftone is always of a greyish cast. It is more difficult to distinguish it from the moon-stone, which appears of a clear fleft colour, when the light is viewed through its thin lamioa, and is somewhat transparent; circumstances not observed in the adularia. It is harder than common felt spar, and less hard than quartz : it is cold to the touch, with difficulty scraped with the knife, and generally itrikes fire with steel. lis weight varics, as it is more or less transparent and friable; generally betu een

2,550,

and 2,600. It is not attacked by acids ; it nei ther decrepitates or becomes phosphoric in the fire; it runs to a white glass filled with little microscopic globules ; in the dry way it is diffolved with effervescence by means of borax, and impe:fectly, without effervescence, by mineral alkali. In moun. tains, it forms strata between those of the faxum fornacum and

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veined granite : it may, like other felt spars, occur in threads or be a component part of other stones. Our author, M. Struve, thinks it only a variety of common felt fpar and related to it, as the Iceland spar is to the common calcarcous fpar. Its analysis has been given differently. M. Morell tound in 100 grains, 13 grain of water ; of 'fiint 6275 ti of clay 1994 nagnelia si ; of selenite 10?; but he speaks, with diffidence, ot his real success. The white felt spar contains more flint, less clai, and terra ponderosa, instead of lime.

M. Dodun has added to our knowledge of this substance, by deferibing the species found in the black mountain in Languee dec. He thinks M. Struve too rash in calling it a felt spar, because to the form of crystallization the same integrant parts should be added The adularia of Languedoc is found in the fiffures of the black micacious granatoid rock, following its calcareous bands, which alternate with the granatoid. It is in these fiffures, which contain the elements of the matrix, and in which the adula' ia seems a secondary formation, that it must be chicfly fought; but it is by no mzans o transparent as that described by M. Struve. This species is harder than felt spar and less hard than quartz : it with difficulry Itrikes fire with steel, though steel does rot injure its solid angles. Its faces are veined with a dirty white, and with green, more or less deep; in some places cats-eyed. The fracture is like that of quartz, but not very brilliart: ja laminated structure is orly ascertained by the belp of the microscope. Borax does not wide folve it with effervescence, on a support of charcoal. Afie of half a hour's continuance is necessary to fuse a piece not larger than the head of a pin ; and it appears in borax as a white fpot, not unlike opaque quartz. The glass is of a g'eyith white, with many fine microscopic cellules. M. Dodun has not yet analyzed it in the moist way.

Another mineral, whose nature we have lately underf od more accurately, is the Prelinite of Werner, so called, because it was given him at the Cape of Good Hope, where it occurs, by colonel Prchn. This mode of denominating crystals is justly reprehended by M. Sage, to whom we are indebted for our informasi in refpecting its analysis. The latter formerly called it the chrysolite of the Cape; but, on more accurate en. quiry, found it to be a schorl. It is the No. 81 of the cabinet of the royal school of minerals, thus defined : ' a green clcar transparent schorl, lamellared, striking fire with i cel.' In the fire, it foon,lofes its transparency; when the heat i« inçreaf:d, it swells, and produces a greenish brown cellular ena. mel, which does not concrete in maffes. The colouring matter is iron, and it is discovered by the same process as in the sappare. Werner would class this green stone of the Cape between the zcolite and the schorls ; M. Jacquet calls it a crys. tallised prasos ; M. Bruckman thinks it a felt spar; M. Halseniratz has detined it in the following manner; "a flinty, cab.

Carcous,

sareous, aluminous, magnefian, iron-fione, of a green colour in laminated mailes, femitranfparent and crystallized in bundles on the surface.' On analyzing, he found it to cunsain of fint 50 ; lime 23:4; alum 20.4 ; cals of iron 4.9; water 9; magnesia 5. M. Klaproth's analysis difiers only in the proportions, and his not discovering 'magnelia. It contains, accord ing to this author, of flint 43%; alum 30}; lime 181; iron 5i; water and air 1!.

M. Bournon formerly defcribed the pechtein of Menil montant, which has been found to contain magnefa; but, as other stones, apparently of the fame kind, produced so bitter falt, when cared with vitriolic acid, philosophers were inclined to exclude this fpecies from the class. Mr. Boumon, though he allows it to differ in this respect, yet thinks it agrecs in so many others, as to deserve the denomination. He reits, however, on its containing only a bituminous matter, which he connects with his own system of lithology; but, in this part of his memoir, the proofs feem to be detective. He calls that oily subítance which in the mother water prevents crystallization, the mineral fat. Onfimilar grounds, he connects the hydrophaa nous ftone with the pechficio, calcedony, fardonix, opal, agate, jasper, filex, and petro fiiex.

M. Afzelius Arvidson has described the different kinds of heavy spar found in Sweden, and added an analysis of each. The specific gravity varies from 4.583 to 3.892. They contain a pretty large proportion of pure heavy spar, from 93 10 55 parts in 100; but the average proportion is about 65, fome pure selenite, a little pure vitrifiable earth, fome ocrous clay, a very little water, and occasionally some aerial subitance of an uncertain nature. Onc kind does not contain the selenite, and another, with the selenite, has about .08 of aerated calcareous carth.

We shall conclude our sketch, fince an account of the other objets of chemitry would at present lead us too far, with a translation of one or two of M. Crell's letters to M. D'Arcet and M. de la Matherie : they are as usual, interesting and inftructive, though concise and abrupt. The firit is to M. D'Ar

Sir, M. Schiller wrote me, fome days fince, that, by mixing one part of sal ammoniac, three parts of potash, with one part and a half of water, distilling these ingiejients, till all the crystallizable salt had passed over, and then changing the receiver, he obtained a liquid, which appeared, in every respect, like the best phlogisicated alkali. I have a curiolity to examine, if this bappens with every kind of fal ammoniac, or is peculiar to that of Egypt, which still contains some particles of the foot unmixed. M. Weltrumb has analyzed the calculus from the bladder of a horse, and the incrustations of chamber pors, without finding the acid discovered by Scheele, Bergman, and Prugnatelli. But, besides a confiderable quantity of oily

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phlogison, he found some volatile alkali, calcareous earth, and phosphoric acid. This chemiit has also analyzed different fpecimens of sulphur from the shops, and has discovered in it fome arsenic and a little calcareous earth. The presence of arse. nic is calily explained; but the calcareous earth, which is found even in the flowers of sulphur, is it a constituent part, or even the base of phlogiston ? the quellion is yet undecided.

The next is to M. de la Mctherie.

M. Weftrumb has proved by new experiments that all the vegetable acids, when the analysis is carried to the utmost point, yield plafphoric and aerial acids. These are obtained hy employing nitrous and depblogisticated muriatic acids. If the vegetable acids are treated with pure vitre, he finds the phosphoric acid alone : he will soon publin the proofs of this very new discovery. I have seen with plcafure, from your letter, that the antiphlogistic theory makes no progress in foreign countries; that, on the contrary, it seems to lose ground, If Dr. Priestley's new experiments be farther confirmed, of which I entertain no doubt, this theory will lose its fupport; and we fall only find the numerous difficulties which have been already objected to it.

TH

MONTHLY CATALOGUE.

FRENCH AFFAIRS. Tle Speech of Mr. Necker, Director General of the Finances, at

tbe Meeting of the allembly of Notables, beld at Versailles, November 6, 1788. To which is added, the King's and the Kerpe

rr's Speeches. 8vo. 15. Debrett. THE Speech contains in embryo the future organization of

the affembly of the states-general. It rather proposes sub. jects of deliberation, than offers any decided opinion. It is flight, pompous, and un mportant. Mr. Necker's Report to his most Christian Majesty in Council, ar.

nouncing important Changes in tbe French Government. Trans lated from the Frenib. 8vo. Debrett.

In the Report before us, the comptroller of the finances speaks more openly; but his advice of increasing the number of commons, and ot admitting at least of a thousand deputies, has laid the foundation of the liberties, perhaps of the continued, anarchy of France. Each proposal was equally injudicious. Extrait de la Requête Addrefle au Roi par M. de Calonne, Mi.

nifre d'Etat. 8vo. Robson. In the struggle with clamorous authors, and numerous im. portant Engli/h publication, M. Caloune's Requête au Roi eScaped us; and, when we turned to it, we had little tempta: pion to enlarge on a political debate, which, at that time, ap;

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