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parts of bismuth, five of lead, and three of tin,' will melt in a heat hardly sufficient to cause water to boil. Copper decomposes, sal ammoniac by distillation. It unites with sulphur, and forms the æs veneris, which is used 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 vessels. Hence also the composition of bronze and of reflecting speculums. Mr. Edwards has lately made an improvement on this subject. We shall transcribe the account,

. He first melts thirty-two parts of copper as Auid as possible, 4. with one part of brass and one of silver, together with the black « flux; at the same time that fifteen parts of tin are melted in a' • separate crucible by itself. These being taken from the fire, he : A pours the tin to the copper, immediately stirs the whole toge.

ther with a wooden spatula, and pours the whole out hastily 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 necessary to fuse this metal, a part of the tin

would be calcined, and the metal would abound more or less ( with finall microscopic pores. If one of the pieces of the cold

metal be broken, it will appear of a most beautiful bright colour, • resembling quicksilver. Mr. Edwards affirms that different kinds

of copper require different doses of tin to produce the most. perfect whiteness. If the dose of tin be too small, which is the

fault most easily remedied, the composition will be yellow;- if it ( be too great, the composition will be of a grey blue colour,

and dull appearance. He therefore finds, by trial, the quantity of tin necessary to be added in the second fusion to render the

metal the most perfect. A much less heat is then required to Smelt the compound. In the second melting he adds one part of $ arsenic, and immediately stirs the mixture, which he pours into

the mould as soon as the fumes of the arsenic have cealed to ? arise. He casts the speculum in sand, with the face downwards;

takes it out while red-hot, and places it in hot wood-alhes to cool ; without which precaution it would break in cooling.'

Mr. Nicholson now proceeds to consider the most useful of all the metals, iron. He relates its properties and various combinations with tolerable accuracy; the production of ink, Prussian alkali, &c. He properly observes that the compound of iron and sulphur, neither of the ingredients containing water, might perhaps furnish data to decide which of the op. posite systems in chemistry is founded in nature. The author describes the different states in which iron is found, and the mes thods employed for analising the ores and extracting the metal. Iron decomposes fal ammoniac by the assistance of heat, and the

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falx

calx produces the same 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 formod upon the subject.-Tin is next in order, . It dissolves in concentrated vitriolic acid, and, by absorbing oxygen from the acid, converts it into fulphur. By long standing, or the effusion of water, a white calx is thrown down. When tin is dissolved in nitrous acid, volatile alkali is formed. The water is decomposed, the oxygen calcines the metal, while the hydrogen joins the azote furnished by the acid, and composes the alkali. The solution of tin in aqua regia is used by the dyers to convert a crimson colour into a bright scarlet. Tin decomposes sal ammoniac. With sulphur it forms the curious mass named aurum mufivum. If the crystals of nitrous copper be grossly powdered, moistened, and rolled up in tin-foil, the salt deliquesces, nitrous fumes are .. emitted, the mass becomes hot, and suddenly takes fire. The semi-metals come next to be considered. Bismuth, diffolved in nitrous acid, fubfides when the solution is diluted with water, in the form of a fine white calx, which is termed the magistery of bismuth, and used as a cosmetic. The properties of nickel are Nightly mentioned. Arsenic is a subject of more importance, and is treated with greater diffusion. The calx of cobalt is employed to give the fine blue tinge to glass. The solution of cobalt in aqua regia forms sympathetic ink, the characters made with which disappear when dry, but, exposed to the fire, they become of a fine green, and again lose the colour by removal. Zinc is a semi-metal, distinguished by its extreme inflammability. It burns with a dazzling Aame, rapidly calcines, and rises in white flowers, termed philosophical wool. When the calx is. urged by a strong heat, it is converted into a yellow glass. Zinc, fuled with vitriolated tartar, absorbs the oxygen from the acid and forms liver of sulphur, If pulverised, it detonates violently with nitre. Zinc décomposes alum, common salt, and fal am. moniac. It is generally obtained by distilling its ore, calamine, with charcoal, and is known in the arts by the name of spelter. The calx of antimony enters readily into the composition of glass, and communicates a hyacinthine tinge. The semi-metal detonates with nitre, and forms diaphoretic antimony. It partly converts vitriolated tartar into liver of sulphur. The regulus combined with sulphur 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 fusion with earths and faline substances, and communicates a deep red or purple tinge. The colour is heightened by the degree of calcination; and hence infiammable matter discharges it, but the addition of nitre

again restores it. The ore of manganese, known in Derbyshire by the name of black wadd, is remarkable for its spontaneous inflammation with oil.Tungsten, 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 distinguished from black-lead by its thining scaly appearance.. It is very scarce, and has not been much examined.

Mr. Nicholson 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, araber, sulphur, and plumbago. He properly observes that most of these are really animal and vegetable productions, .. which have undergone various modifications in the bowels of the earth. The diamond also must be referred to the class of combustible minerals; for it has been lately discovered that, in an intense heat, it is totally consumed, and leaves not the smallest trace,

Mr. Nicholson now begins the consideration 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, farch, gluten, fat oils, essential oils, camphor, resins, the aromatic principle, and the colouring matter.

We have next a tolerably distinct view of the faline substances obtained from vegetables.' Lemon-juice may be preserved for : some time under a thin stratum of oil. : In the Eait-Indies it is evaporated to the consistence of a thick extract. But the best method is to congeal the watery part by exposing it to a cold, seven 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 salt thus formed decoma posed with vitriolic acid. Another acid, that of apples, is procured by faturating the sour juice with vegetable alkali, adding

sugar 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 solution be evaporated, small brilliant crystals of 2 grey yellowilh colour are obtained. The acid of benzoin is extricated by boiling that fragrant resin in lime-water, and treat. ing the solution 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 selenite thrown down. The falt of sorrel is an acid obtained by crystallising the expressed juice of the wood-forrel and other plants of similar 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. Nicholson next proceeds to consider fermentation, putrefaction, &c, and the production of ardent spirita He describes. the process for obtaining æther by treating spirit of wine with the vitriolic acid, the nitrous, the marine, the acetous, the phosphoric, &c. He enumerates the properties and combinations of distilled vinegar. He then passes to consider the animal substances, milk and its products, wax, lac, silk, &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, simple and double elective attractions, and the proportion of the ingredients in earth and stones. .

In short, we do not refuse Mr. Nicholson the merit of a laborious compiler. In no part of his work does he seem to exercise 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 superficial. Through the whole, he draws his explanations of the phenomena from the opposite theories which have been proposed; and this circumstance, joined to studied conciseness, involves the fubject in greater dark ness. The learner will derive little benefit from the perusal of the work, and the man of science will treat it with contempt.

ART. IV. Surgical Tracts, by the late 7.0. Jufamond, F.R.S., - Surgeon to the Westminster Hospital; consisting of, 1. Outlines of

the History of Surgery, from the carliejt Antiquity of the Art, pointing out the particular Improvements, and fixing them where due. 11. An Esay on Inflammation and Abscess, with their proper Modes of Treatment in different Parts of the Body. III. A Dissertation on the Effects of Motion and Rest, and their Application to the Purposes of Surgery; from the French Prize Memoir by

M. David, with copious additional Annotations on the original 2. Text. IV. Observations on Counter-strokes, and an Account of

their various Consequences, Treatment, &c. from the same. V. On

the Methods employed in treating Cancerous Diseases, including ... Remarks on the Cure of Indurations of the Breast. The whole sollezted and interspersed with occasional Notes and Observations by

; William

William Houlston, Member of the Corporation of Surgeons, Fellow of the Society of Antiquaries, and of the Medical Society of London. 4to. 155. boards, Cadell. London, 1789. . THESE Tracts are the posthumous productions of one who

had acquired a degree of distinction in the practice of surgery, and who blended with the exercise of his profeflion a variety of literary avocations. Though far from being destitute of utility to young surgeons, they are published chiefly from inotives of a very different nature, and such as must always excite the attention of the benevolent part of mankind. The author, amidst the most flattering prospects of success, had experienced the shock of adversity, and was torn for ever from his nearest connexions before it was in his power to replace them in the situation 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 most tender considerations. We shall therefore give a short and impartial account of the tracts now before us,

The first contains Outlines of the History of Surgery, from the remotest period down almost to the present time. In this narrative the author has very properly separated the historical occurrences of furgery from those which relate to the medical art in general; a distinction usually onnitted by writers on the subject, though particularly necessary in the inodern history of two professions. The narrative differs, in several chronological points, from that of preceding writers, and is detailed with great perspicuity.

Next follows an Account of the Qualifications necessary to form a good Surgeon. These, according to our author, are youth, firmness, dexterity, acute sensation, found judgment, and humanity. By youth he means that period of life when the body and mind may be said to enjoy their full vigour; for he thinks there is a time when, if a man is desirous to preserve the reputation he has acquired by long and extensive practice, he should lay aside the knife, and content himself with superintend. ing the operations of others. The author illustrates the several qualifications above specified with much precision, and makes many pertinent observations which are worthy of attention.

The Essay on Inflammation and Abscess, though little disc tinguished by any new observations, affords strong proof of the author's judgment, and knowledge in his profession; which induce us to regret that he has not treated of some of the subjects more copiously. His account of the whitloe and its feveral distinctions, with the reasons for the treatment recommended, may justly be considered as highly valuable to young surgeons.

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