parts of bifmuth, five of lead, and three of tin, will melt in a heat hardly fufficient to caufe water to boil. Copper decompofes fal ammoniac by diftillation. It unites with fulphur, and forms the as veneris, which is ufed by dyers and callico printers. Copper unites also with phosphorus. It has a strong attraction for tin; and hence is founded the process for tinning copper veffels. Hence alfo the compofition of bronze and of reflecting speculums. Mr. Edwards has lately made an improvement on this fubject. We fhall transcribe the account.

He firft melts thirty-two parts of copper as fluid as poffible, with one part of brafs and one of filver, together with the black flux; at the fame time that fifteen parts of tin are melted in a • feparate crucible by itself. These being taken from the fire, he pours the tin to the copper, immediately ftirs the whole together with a wooden fpatula, and pours the whole out haftily into, a large quantity of cold water, which cools and granulates the compofition. If the tin were fused together with the copper, ་ or if they were to remain for any length of time in the extreme heat which is neceffary to fufe this metal, a part of the tin would be calcined, and the metal would abound more or lefs ' with finall microfcopic pores. If one of the pieces of the cold ⚫ metal be broken, it will appear of a most beautiful bright colour, resembling quickfilver. Mr. Edwards affirms that different kinds of copper require different dofes of tin to produce the most. perfect whiteness. If the dofe of tin be too small, which is the fault moft eafily remedied, the compofition will be yellow;- if it be too great, the compofition will be of a grey blue colour, and dull appearance. He therefore finds, by trial, the quantity of tin neceffary to be added in the fecond fufion to render the metal the most perfect. A much less heat is then required to 'melt the compound. In the fecond melting he adds one part of arfenic, and immediately ftirs the mixture, which he pours into the mould as foon as the fumes of the arfenic have ceased to arife. He cafts the fpeculum in fand, with the face downwards; takes it out while red-hot, and places it in hot wood-afhes to cool; without which precaution it would break in cooling.' Mr. Nicholfon now proceeds to confider the most useful of all the metals, iron. He relates its properties and various combinations with tolerable accuracy; the production of ink, Pruffian alkali, &c. He properly obferves that the compound of iron and fulphur, neither of the ingredients containing water, might perhaps furnish data to decide which of the oppofite fyftems in chemiftry is founded in nature. The author defcribes the different states in which iron is found, and the methods employed for analifing the ores and extracting the metal. Iron decompofes fal ammoniac by the affiftance of heat, and the

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calx produces the fame effect in the common temperature. He explains the process of converting it into steel, and gives an account of the theories which have been lately formed upon the fubject.-Tin is next in order. It diffolves in concentrated vitriolic acid, and, by abforbing oxygen from the acid, converts it into fulphur. By long ftanding, or the effufion of water, a white calx is thrown down. When tin is diffolved in nitrous acid, volatile alkali is formed. The water is decompofed, the oxygen calcines the métal, while the hydrogen joins the azote furnished by the acid, and compofes the alkali. The folution of tin in aqua regia is ufed by the dyers to convert a crimson colour into a bright fcarlet. Tin decompofes fal ammoniac. With fulphur it forms the curious mafs named aurum mufivum. If the crystals of nitrous copper be grofsly powdered, moistened, and rolled up in tin-foil, the falt deliquefces, nitrous fumes are emitted, the mafs becomes hot, and fuddenly takes fire. The femi-metals come next to be confidered. Bifmuth, diffolved in nitrous acid, fubfides when the folution is diluted with water, in the form of a fine white calx, which is termed the magiftery of bifmuth, and used as a cofmetic. The properties of nickel are flightly mentioned. Arfenic is a fubject of more importance, and is treated with greater diffufion. The calx of cobalt is employed to give the fine blue tinge to glafs. The folution of cobalt in aqua regia forms fympathetic ink, the characters made with which disappear when dry, but, exposed to the fire, they become of a fine green, and again lofe the colour by removal. Zinc is a femi-metal, diftinguished by its extreme inflammability. It burns with a dazzling flame, rapidly calcines, and ries in white flowers, termed philofophical wool. When the calx is urged by a ftrong heat, it is converted into a yellow glafs. Zinc, fufed with vitriolated tartar, absorbs the oxygen from the acid and forms liver of fulphur. If pulverifed, it detonates violently with nitre. Zinc decompofes alum, common falt, and fal ammoniac. It is generally obtained by diftilling its ore, calamine, with charcoal, and is known in the arts by the name of fpelter. The calx of antimony enters readily into the compofition of glafs, and communicates a hyacinthine tinge. The femi-metal detonates with nitre, and forms diaphoretic antimony. It partly - converts vitriolated tartar into liver of fulphur. The regulus combined with fulphur is named crude antimony. Emetic wine is formed by infusing powdered glass of antimony in white wine. Tartar emetic is a compound of tartar and the calx of antimony. The calx of manganese unites in fufion with earths and faline fubftances, and communicates a deep red or purple tinge. The colour is heightened by the degree of calcination; and hence inflammable matter discharges it, but the addition of nître

again reftores it. The ore of manganefe, known in Derbyshire by the name of black wadd, is remarkable for its spontaneous inflammation with oil.-Tungften, or wolfram, is a metal lately discovered, the properties of which are not well ascertained; nor is it certain whether it be not a natural compound. Molybdena is diftinguished from black-lead by its fhining fcaly appearance. It is very scarce, and has not been much examined.

Mr. Nicholfon next proceeds to enumerate the combustible minerals. These are inflammable air, hepatic air, naptha, petroleum, Barbadoes tar, asphaltum, mineral tallow, jet, pit-coal, peat, turf, amber, fulphur, and plumbago. He properly obferves that most of these are really animal and vegetable productions, which have undergone various modifications in the bowels of the earth. The diamond alfo must be referred to the class of combustible minerals; for it has been lately discovered that, in an intense heat, it is totally confumed, and leaves not the fmalleft trace.

Mr. Nicholson now begins the confideration of the vegetable kingdom. He makes fome general remarks upon the functions of organised beings, and gives a hort account of the various vegetable productions; mucilage, fugar, ftarch, gluten, fat oils, effential oils, camphor, refins, the aromatic principle, and the colouring matter.

We have next a tolerably diftinct view of the faline substances obtained from vegetables. Lemon-juice may be preserved for fome time under a thin ftratum of oil. In the Eaft-Indies it is evaporated to the confiftence of a thick extract. But the best method is to congeal the watery part by expofing it to a cold feven or eight degrees below the freezing point. To obtain the acid in its greatest purity, the lemon-juice ought to be boiled with chalk, and the compound falt thus formed decompofed with vitriolic acid. Another acid, that of apples, is procured by faturating the four juice with vegetable alkali, adding fugar of lead, and treating the precipitate with vitriolic acid. The acid of galls is evolved by maceration in water. Ardent spirit does not affect the mucilaginous part, but diffolves the falt; and if this folution be evaporated, fmall brilliant cryftals of a grey yellowish colour are obtained. The acid of benzoin is extricated by boiling that fragrant refin in lime-water, and treating the folution with marine acid. The cream of tartar is a compound of vegetable alkali. The acid is obtained in fine crystals, by the addition of vitriolic acid and flow evaporation. Or lime may be added to the cream of tartar, when the acid will remain in the solution, and felenite thrown down. The falt of forrel is an acid obtained by cryftallifing the expressed juice of the wood-forrel and other plants of fimilar properties.

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Some acids are expelled from vegetables by the application of fire; others are obtained by treating them with nitrous acid. The number of these have lately been diminished; and it is probable that they are all capable of being converted into each other.

Mr. Nicholfon next proceeds to confider fermentation, putrefaction, &c. and the production of ardent spirit. He defcribes. the process for obtaining æther by treating spirit of wine with the vitriolic acid, the nitrous, the marine, the acetous, the phofphoric, &c. He enumerates the properties and combinations of diftilled vinegar. He then paffes to confider the animal fubftances, milk and its products, wax, lac, filk, &c. the blood, the bile, the mucilage, &c.

Several useful tables are added in an appendix. The comparative heats of different bodies, the weights of different countries, the specific gravities of bodies, fimple and double elective attractions, and the proportion of the ingredients in earth and ftones.

In short, we do not refufe Mr. Nicholson the merit of a laborious compiler. In no part of his work does he seem to exercife his own judgment. He has collected a number of facts, but he has described them in a manner equally confused and inelegant. His general views are extremely lame and fuperficial. Through the whole, he draws his explanations of the phenomena from the oppofite theories which have been proposed; and this circumftance, joined to ftudied conciseness, involves the fubject in greater darkness. The learner will derive little benefit from the perufal of the work, and the man of science will treat it with contempt.

ART. IV. Surgical Tracts, by the late J. O. Juftamond, F. R.S. Surgeon to the Westminster Hofpital; confifting of, 1. Outlines of the History of Surgery, from the earliest Antiquity of the Art, pointing out the particular Improvements, and fixing them where due. II. An Esay on Inflammation and Abfcefs, with their proper Modes of Treatment in different Parts of the Body. III. A Differtation on the Effects of Motion and Reft, and their Application to the Purpofes of Surgery; from the French Prize Memoir by M. David, with copious additional Annotations on the original Text. IV. Obfervations on Counter-Strokes, and an Account of their various Confequences, Treatment, &c. from the fame. V. On the Methods employed in treating Cancerous Difeafes, including Remarks on the Cure of Indurations of the Breaft. The whole collected and interspersed with occafional Notes and Obfervations by

William

1

William Houlton, Member of the Corporation of Surgeons, Fellow of the Society of Antiquaries, and of the Medical Society of London. 4to. 15s. boards. Cadell. London, 1789.

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HESE Tracts are the pofthumous productions of one who had acquired a degree of diftinction in the practice of furgery, and who blended with the exercise of his profeffion a variety of literary avocations. Though far from being destitute of utility to young furgeons, they are published chiefly from motives of a very different nature, and fuch as must always excite the attention of the benevolent part of mankind. The author, amidst the most flattering profpects of fuccefs, had experienced the fhock of adverfity, and was torn for ever from his nearest connexions before it was in his power to replace them in the fituation from which he had fallen. Pofthumous works are always particularly entitled to the candour of criticism; the justice of which, however, ought never to be violated, even from the moft tender confiderations. We fhall therefore give a short and impartial account of the tracts now before us.

The first contains Outlines of the Hiftory of Surgery, from the remoteft period down almoft to the present time. In this narrative the author has very properly feparated the historical occurrences of furgery from those which relate to the medical art in general; a distinction usually omitted by writers on the fubject, though particularly neceffary in the modern history of two profeffions. The narrative differs, in feveral chronological points, from that of preceding writers, and is detailed with great perfpicuity.

Next follows an Account of the Qualifications necessary to form a good Surgeon. Thefe, according to our author, are youth, firmness, dexterity, acute fenfation, found judgment, and humanity. By youth he means that period of life when the body and mind may be faid to enjoy their full vigour, for he thinks there is a time when, if a man is defirous to preferve the reputation he has acquired by long and extenfive practice, he fhould lay afide the knife, and content himself with fuperintending the operations of others. The author illuftrates the feveral qualifications above fpecified with much precifion, and makes many pertinent obfervations which are worthy of attention.

The Effay on Inflammation and Abfcefs, though little dif tinguished by any new obfervations, affords ftrong proof of the author's judgment, and knowledge in his profeffion; which induce us to regret that he has not treated of fome of the fubjects more copioufly. His account of the whitloe and its feveral diftinctions, with the reafons for the treatment recommended, may justly be confidered as highly valuable to young surgeons.

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