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principles of that important science. The melting of ores, the manufacturing of metals, the elegance and durability of dying, the making of glafs, porcelain, &c. all derive their beauty and utility from this effential object of modern inveftigation; yet thefe proceffes are in general conducted by artists whofe chemical knowledge confifts in nothing more than a confiderable degree of certainty and ingenuity, which they have acquired by practice. But should there arife any unexpected circumstance, to which they are ftrangers, they find themselves involved in a difficulty from which practical knowledge alone cannot extricate them; and many loffes muft unavoidably be incurred in working, unless they can have recourse, on fuch occafions, to the principles of chemistry.

To obviate these great inconveniencies in the metallic arts, has been the inducement to the prefent publication, which is by no means intended as a perfect fyftem on the fubject, but merely to communicate fuch a degree of knowledge as will prove ufeful to manufacturers, and facilitate the understanding of more scientific writers to those who are defirous of farther information. We must add, however, in juftice to the exccution of the work, that authors of the greatest eminence appear to have been confulted and ufed on the prefent occafion; and when they have been deficient in point of practice, we find that application has been made to working artifts; fo that every endeavour has been exerted to render the treatise as useful as poffible.

The work begins with an introduction to the study of chemistry; in which the author gives a concife account of the various proceffes of the different claffes of fubftances, which are comprised in the province of this art. The following article, taken from the clafs of mineral acids, may ferve as a fpecimen :

Vitriolic acid, commonly called oil of vitriol, or fpirit of vitriol. The vitriolic acid is fo called from the ancient method of extracting it from green vitriol. But now it is more profitably obtained from the combustion of fulphur. This acid, when perfectly pure, is tranfparent; but its attraction for phlogiftic fubftances is fo ftrong, that, whenever it comes in contact with them, it foon becomes of a dark colour. Its specific gravity is double that of water; for if a pint of water weigh one pound, the fame quantity of vitriolic acid will weigh two pounds. It has a very strong attraction for water.

It formerly was obtained from green vitriol and pyrites, by dif tillation. Sulphur was found to produce it in great abundance from combuftion; confequently that fubftance was burnt under a large glafs bell; the condensed vapour was an impure vitriolic acid, which was purified either by fimple diftillation, or by the addition of a small

quantity

quantity of nitrous acid; which attracts the phlogifton, and is afterwards eafily evaporated away by a gentle heat. This was called oleum vitrioli per campanam; or, oil of vitriol by the bell. It is now obtained by the combuftion of fulphur, in rooms properly conftructed and lined, which are called fulphur chambers. It unites with alkalies, earths, and metals, forming various neutral falts. When united with phlogifton it is volatilifed, and has a very penetrating fmell; in which state it is called volatile fulphureous acid.'

After the introduction, the author proceeds to the confideration of mines and ores, commonly called metallurgy, which comprehends not only the extraction of metals from their different ores, but the converfion of fuch metals either to useful or ornamental purposes. Mines, or the repofitories of ores, are in general confined to mountains, which are, in the language of metallurgic writers, entire, ftratified, or confufed; and these several kinds the author defcribes with perfpicuity. For the convenience of fuch of our readers as are unacquainted with - this fubject, it may not be improper to explain the leading terms which are employed by those who are converfant with it.

Miners diftinguish the courfe of veins, with respect to the meridian, by the term direction; and, with relation to the horizon, by that of inclination. Their direction is either morning, noon, evening, or night; by which is understood, as it pants towards that divifion of the compafs where the fun is at any of those periods of the natural day. They have likewise names expreffive of their difference, as deep, perpendicular, horizontal, hanging, dilated, rich, or poor. Small veins will fometimes diverge from larger ones, and frequently return into the trunk whence they iffued. These are called flips, and are in general very rich. The fuperior ftratum of earth or stone, immediately in contact with the vein, is its roof; the inferior ftratum on which it refts, is the floor.

Mineralogifts confider thofe mountains as most metalliferous which have a gentle afcent, a moderate height, and a broad bafis, the ftrata of which are nearly horizontal, and not much broken; at least in fuch mountains the veins are less interrupted, more extended, and confequently more valuable to miners, than those in high, craggy, irregular, and sheltered mountains.

Our author obferves, that metallic ores are found in two ftates, viz. firft, calciform; and, fecondly, combined with different extraneous fubftances, by which they are faid to be mineralifed. The calciform ores are metals deprived of their metallifing principle, viz. phlogifton, as the lapis calaminaris, which is an ore of zinc, and the different ocres which are the

calces

calces of iron. These ores contain a confiderable quantity of fixed air.

The most common mineralifers are fulphur, arfenic, the vitriolic, marine, and phosphoric acids; one fpecies of iron ore appears to be mineralifed by the acid of Pruffian blue. Some mineralogifts have excluded arfenic as a mineralifer, alledging that it is a metal of itself, and never united to other metals but in a reguline state; therefore, that the compound it forms fhould rather be called an alloy than an ore. But, as metals which are found united, either with the calx of arfenic or its acid, are in a greater or lefs ftate of dephlogiftication, arfenic ought to be admitted as a mineralifer in the ftricteft fenfe of the word; particularly as no fuch union, without a dephlogiftication of the metal united, has ever been exhibited in the mineral kingdom. The following are the author's directions for making an affay of filver ores:

I. Take the affay quantity of the ore finely powdered, and roast it well in a proper degree of heat, frequently irring it with an iron rod; then add to it about double the quantity of granulated lead; put it in a covered crucible, and place it in a furnace; raife your fire gently at firft, and continue to increase it gradually till the metal begins to work; if it fhould appear too thick, make it thinner by the addition of a little more lead; if the metal fhould boil too rapidly the fire fhould be diminished. The furface will be covered, by degrees, with a mass of scoria, at which time the metal fhould be carefully ftirred with an iron hook heated, efpecially towards the border, left any of the ore should remain undiffolved; and if what is adherent to the hook when you raise it from the crucible melts quickly again, and the extremity of the hook, after it is grown cold, is covered with a thin, fhining, fmooth cruft, the fcorification is perfect; but, on the contrary, if, while you are stirring it, you perceive any confiderable clamminefs in the fcoria, and when it adheres to the hook, though red-hot, and appears unequally tinged, and feems duty or rough with grains interfperfed here and there, the fcorification is incomplete; in confequence of which the fire fhould be increafed a little, and what adheres to the hook fhould be gently beaten off, and returned, with a small ladle, into the crucible again. When the fcorification is perfect, the metal fhould be poured into a cone, previously rubbed with a little tallow, and, when it becomes cald, the fcoria may be feparated by a few strokes of a hammer. The button is the produce of the affay. Or,

II. By cupellation. Take the affay quantity of ore, roast and grind it with an equal portion of litharge, divide it into two or three parts, and wrap each up in a small bit of paper; put a cupel, previously feafoned under a muffle, with about fix times the quantity of lead upon it. When the lead begins to work, carefully put ore of the papers upon it, and, after this is abforbed, put on a fecond, and fo on till the whole quantity be introduced; then raise the fire, and

as

as the fcoria is formed, it will be taken up by the cupel, and at laft the filver will remain alone. This will be the produce of the afsay, unless the lead contains a small portion of filver, which may be difcovered by putting an equal quantity of the fame lead on another cupel, and working it off at the fame time; if any filver be produced, it must be deducted from the affay. This is called the witness.'

The fecond part of the work treats of metals and metallic compounds. The metals at prefent accurately known, our author obferves, are seventeen in number; exclufive of fiderite, first distinctly mentioned by Mr. Monnet; of faturnite, faid by the fame author to be found in the lead mines of Poullaoven, in Brittany; and of the femi-metal called uranite, difcovered by Mr. Klaproth, of Berlin.

Our author relates, very diftinctly, the opinions of chemifts respecting the conflituent parts of metals; but for this we must refer to the work. Paffing likewise over the account of the feveral metals, which are defcribed with much precifion, we shall only, for the information of our readers, prefent them with the following extract, as relative to objects of curiofity:

The most aftonishing fubftance in all chemistry is produced from filver, difcovered by Mr. Berthollet, and called by him fulminating filver. It is prepared as follows: Diffolve cupelled filver in pure or dephlogifticated nitrous acid. Precipitate the filver with lime-water; then decant the liquor, and expofe the precipitate for the space of three days to the air. Mr. Berthollet imagines that, at this period of the experiment, the prefence of light may have an influence on its fuccefs. To this calx, when dry, add cauftic volatile alkali; it will take the form of a black powder. Decant the liquor, and let the powder dry in the air. This is fulminating filver, which cannot bear to be touched by any cold body without fulminating; fo that it muft remain in the capfule in which it was dried. The volatile alkali used in the preparation, being boiled in a thin matrafs, forms cryftals, which, being touched under the liquor, fuddenly detonate and break the veffel.

• Arbor Diana, or Philofophical Tree.

This is a matter of curiofity only. Make an amalgam of filver and mercury, and diffolve it in a fufficient quantity of pure aqua fortis; dilute it in about four times its weight of diftilled water, and cork it down quite tight. When it is wanted for use, a little of it is poured into a bottle, and a fmail piece of an amalgam of gold or filver put in, when it must remain at reft; fmall filaments foon fhoot from the amalgam, which branch out on all fides, and take the form of fhrubs.'

In the third part of the work an account is given of metallic calces and precipitates; and, in the fourth, the author delivers

a fhort

a fhort account of the principal diseases of metallic artists; with fome plain directions concerning their prevention and cure.

The whole of this work is judiciously compiled, and will prove highly useful to those artists who are employed in the extraction of metals, or in any of their preparations.

ART. VII.

Norman and Bertha; or, The exalted Attachment: 12mo. 2 vol. 6s. fewed. Walter.

a Novel. By a Lady. London, 1790.

WITH pious refignation to our fate, which imposes upon us the task of examining thofe crude productions, which, under the name of novels, the prefs daily throws upon the public, and prepared to drudge through those dull scenes of hacknied defcription, of affectation, of flippancy, and bombaft, which this fpecies of literary compofition generally exhibits, we took up the ftory of Norman and Bertha. But how agreeable was the difappointment to obferve, as we proceeded, the moft picturesque fcenery rifing on our view, and to feel the rays of genius dancing on a landscape which the pencil of fenfibility had sketched! The charming scenes of this interefting novel are dignified by the moral leffon which they are intended to convey : That the

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pureft bleffings which mortals can experience, flow from a chafte and honourable union of hearts, produced and confirmed by a fimilarity of virtues and fentiments.' Few novel writers have poffeffed, in an equal degree with the fair author of Norman and Bertha, the art of giving truth, life, and interest, to their portraits. From many examples, let the reader take the following defcription of Mrs. Westbrooke:

That lady was one of thofe exquifitely delicate and fine proportioned forms that might vie with the famed ftatue of the Venus de Medicis, and was a no lefs faultlefs model of perfect fymmetry. Her movements were all grace, her voice all harmony. Her complexion was foft and clear; time and forrow had borne away the roses of health, but left a pallid mildnefs in their ftead which rendered her inexpreffibly touching to the foul where generous feelings dwell. Her features not regular, but yet beautiful; her eyes dark, large, and expreffive-fpoke at once the native ftrength, vivacity, and tendernefs of her mind; her hair ftill retained its gloffy chefnut, and o'er her fpeaking features was diffused

That expreffion fweet of melancholy
Which captivates the foul.'

Her fufferings had likewife given a firmnefs to her character, which, blended with its native foftnefs, rendered her no less refpect

able

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