from an artificial cinnabar, composed of 8 parts of mercury and 1 of sulphur. When sulphur and mercury are triturated together in a mortar, the former gradually disappears, and the whole assumes the form of a black powder, denominated ethiops mineral; if this powder be heated red-hot, it sublimes, and on a proper vessel being placed to receive it, a cake is obtained, of a fine red colour, which, when reduced to powder, forms the vermilion of

commerce.

ANTIMONY.

This metal was discovered by Basil Valentine in 1490, and has since been extensively employed in medicine, in the composition of printing types, stereotype plates, music plates, and the like; and also in the manufacture of the white metal utensils now so generally used as substitutes for silver. When pure, it is of a silver-white colour, is brittle, has a specific gravity of 68, and melts readily at a red heat. When heated in open crucibles, it gradually combines with the oxygen of the atmosphere, and flies off in the form of a white vapour. It is the oxide, or rather oxides of the metal (for there are several) which are used in medicine, their general effects being purgative, sudorific, and emetic. The metallic ore of commerce contains sulphur and other impurities, and is much more easily fused than the pure metal, which has a hardness about that of gold. This ore is found at Rosenau in Hungary, in Saxony and the Hartz, in Spain, France, Siberia, Mexico, the Indian Archipelago, and in Cornwall and Ayrshire in our own island. As yet the ore has been imported into this country chiefly from the East; but the recently discovered veins in Ayrshire are likely soon to yield the main supply. It is usually of a lead-gray colour, is crystallised, possesses considerable splendour, and is very apt by the uninitiated to be mistaken for an ore of lead. Crude antimony is the name given in commerce to the sulphuret of the metal, after being separated from the impurities of the ore by fusion, and a species of filtration; and regulus of antimony is the pure metal, after being separated from the sulphur. The powder of the sul phuret is very black, and was employed by women in ancient times to stain their eyebrows and eyelids.

Antimony is never applied to any useful purpose as an inde pendent metal, in consequence of its brittleness and liability to corrosion; but it forms several valuable and extensively-employed alloys. Thus, alloyed with lead, in the proportion of 2 to 6, and a small addition of copper, it constitutes the metal used for printing types; mixed with lead alone, the compound forms the rather brittle plates upon which music is engraved; and an alloy of 112 lead, 18 antimony, and 2 block-tin, forms the stereotypes from which the present sheet is printed. Hard pewter is made of 12 parts of tin and 1 of antimony; and the Britannia or whitemetal spoons and teapots now so much in use are composed of 100

tin, 8 antimony, 2 bismuth, and 2 copper. Antimony also unites with iron, forming a hard whitish alloy; and the smallest portion entering into the composition of gold, renders that otherwise soft and ductile metal brittle and unmalleable. The manufacturer of pastes or factitious gems employs the oxide of antimony to give colour to his so-called beryls, Oriental topazes, and yellow diamonds.

BISMUTH.

This metal, known to Agricola in 1530, is of a brittle crystalline texture, brownish-white in colour, nearly 10 in specific gravity, and fusible at the temperature of 476°. Its hardness is between that of copper and lead; it is scarcely malleable, breaks under the hammer, and cannot be drawn into wire. Bismuth is by no means a common metal, and is usually obtained in a combined state in Cornwall, Bohemia, Saxony, and Sweden. As met with in commerce, it is generally mingled with impurities of iron, arsenic, or other metals.

It is used as a flux-that is, for communicating fusibility to other metals; solder, for example, consisting of 1 bismuth, 5 lead, and 3 tin; it is also employed in the formation of some kinds of pewter, printers' types, and various metallic mixtures. Eight parts of bismuth, 5 of lead, and 3 of tin, constitute the fusible metal, sometimes called Newton's, from its discoverer, which melts at little more than 200°, or under the heat of boiling water, and may be fused over a candle in a piece of stiff paper, without burning the paper. A small addition of mercury aids the fusibility; and such alloys are sometimes used in taking casts of anatomical preparations. Bismuth forms the basis of sympathetic ink; and the powder called pearl-white, used in medicine, is obtained from the nitrate of the metal, which, when dropped into water, falls down in that form. The nitrate has also been employed as a mordant for lilac and violet dyes in calico printing.

ZINC.

Though known as early as the beginning of the sixteenth century, the numerous and important applications of this metal are for the most part of very recent date. Its distinguishing characteristics are, bluish-white colour and lustre; specific gravity 7; at common temperatures, tough and intractable; but heated to between 220° and 320° Fahrenheit, it becomes malleable and ductile, so that it may be hammered out, rolled into sheets, and even drawn into wire of such tenacity, that 1-10th of an inch in diameter is capable of sustaining a weight of 26 pounds. Heated beyond that point, say between 400° and 500 Fahrenheit, it again becomes so brittle, that it may be reduced to powder in a mortar: it melts at 700°. The metal is obtained from two ores-namely, calamine, a native carbonate;

and blende, a native sulphuret. These ores occur in two geological positions—namely, either in the native or in the magnesian limestone, associated with galena and sometimes with cadmium.

Zinc ores are found in Britain, especially in Flintshire, Derbyshire, and Cumberland; but the quality of the British metal is inferior to that of Germany, from whence, via Hamburg, about 170,000 cwt. are annually imported, commonly as ballast for ships bringing wool. Of this amount, about one-half is kept for home_consumption, and the remainder for exportation, chiefly to India, which, previous to 1820, obtained her supply from China. "These ores," says Brande, "are roasted and mixed with charcoal; the mixture is put into a kind of crucible, closed at top, and perforated at bottom by an iron tube, which passes through the grate of the furnace into water; and the vapour of the zinc distils downwards through the tube, and is condensed in the water. The first portions are impure, containing arsenic, and often cadmium, in which case the vapour burns with what the workmen call a brown blaze; when the blue blaze appears, the zinc is collected."

Zinc being a cheap and light metal, its specific gravity varying from 6.8 to 7.1, and one which, when superficially oxidised, long resists the further action of air and water, it is now employed as a substitute for lead in lining cisterns, covering roofs, forming water-spouts, and the like. It has also been used of late in the manufacture of kitchen and dairy utensils, but not without doubt as to its being deleteriously acted upon by the presence of acids. It is likewise wrought into buttons, and other smali wares; and zinc-plates have been a considerable while in use in the transfer of printing, under the title of zincography. Its sulphate and oxide are employed in medicine; and, as already described, with copper it forms the well-known alloy, brass. Though the action of water upon zinc be scarcely appreciable, after it has once been coated with the oxide, yet the addition of a little acid (as sulphuric) dissolves and removes this coating, and further oxidation proceeds with rapidity. It is this action which renders zinc so powerful a generator of electricity in the voltaic pile or battery.

COBALT.

Cobalt, discovered by Brandt more than a century ago, is s reddish-gray brittle metal, somewhat soft, fusible at a tempe rature a little below that required for the fusion of iron, of 85 specific gravity, and possessing magnetic properties. The finest ores are found in Saxony, where it received its name (koboid, a devil); a term applied to it by the miners, who considered is unfavourable to the presence of the more important metals. is never used in a separate state; but the impure oxides of the metal, called zaffre and smalts, are extensively used as colouring materials. Thus the oxide of cobalt is an invaluable article an

the manufacture of porcelain and pottery, all the blue colours of which are derived from that substance. When fused with glass, it communicates a blue tint to that material, without impairing its transparency; and what is especially valuable, this colour is not impaired by very high temperatures. So great is the colouring power of oxide of cobalt on vitrifiable substances, that 1 grain gives a full blue to 240 of glass! Cobalt blue, or Thenard's blue, is a beautiful pigment, prepared from the phosphate of cobalt, and now largely employed by decorative painters, and sometimes by artists as a substitute for ultramarine. Smalts, of which we annually import about 146,000 lbs., are prepared principally in Norway and Germany. Zaffre, of which we import more than double that amount, is manufactured chiefly in Saxony and Prussia.

NICKEL.

This metal, discovered by Cronstadt in 1751, is of a brilliant white colour resembling silver; ductile and malleable, and capable of receiving a high polish; specific gravity about that of cobalt. According to Brande, it is found in all meteoric iron; but its principal ore is a copper-coloured mineral found in Westphalia, and called kupfer-nickel, nickel being a term of detraction used by the German miners, who expected from the colour of the ore to find that it contained copper. The cobalt ores are the most fruitful sources of this kupfer-nickel, or speisse. Alloyed with copper, it forms argentane, or German silver; and since this compound became an object of commercial importance, the extraction of nickel has been undertaken upon a considerable scale. It is also employed in potteries, and in the manufacture of porcelain. It is, to a certain degree, susceptible of magnetism, and mariners' compasses may be made of it.

MANGANESE.

This is a very brittle metal, of a dusky white colour, and without either malleability or ductility, having a specific gravity of 8. The substance known in commerce under that name, however, is the peroxide, or the black oxide of the metal. It occurs native in the Hartz mountains, in Piedmont, in the Mendip hills in Somerset, and the counties of Devon and Aberdeen. It is found in a variety of forms: most commonly it is of an earthy appearance, and mixed with other ingredients; but sometimes in crystals of a black colour and metallic lustre. This mineral was described by Scheele, in 1774, as a peculiar earth; but in the same year Gahn showed that it was the oxide of a true metallic substance. The metal separately is of no known use, but the peroxide, as a source of oxygen, is largely employed in the decomposition of common salt for the production of chlorine for bleaching. It is also used by potters and glass-makers as a glaze or pigment; and lately it has been used in calico

printing as the source of certain brown colours. From its cheapness, it is now the only substance used by the chemist for the production of oxygen gas for experimental purposes. The ore of manganese, known in England by the name of black wadd, is remarkable for its spontaneous inflammation with oil. The pure metal can only be kept in closely-stoppered bottles, under naphtha, like potassium; because, when in contact with air, it speedily gets oxidised, and falls into powder.

ARSENIC.

This metal, discovered by Brandt in 1733, is exceedingly brittle, of a strong metallic lustre and white colour, running into steel-gray. Its specific gravity is 5.9; it volatilises, emitting a strong odour of garlic before it fuses, at a temperature of 365°, and is readily inflammable. The pure metal, however, being very soft, is of little value, and is not used in the arts. It is the softest of all the metallic bodies, and so brittle that it may be easily reduced to a very fine powder by trituration in a mortar. The arsenic of commerce is the white oxide of the metal, or, more accurately, arsenious acid—a compound which is obtained chiefly in Bohemia and Saxony, in roasting the cobait ores for making zaffre, and also by sublimation from arsenical pyrites. In this state it is generally met with in cakes, brittle, white, faintly sweetish in taste, and more or less translucent; for medicinal purposes, these cakes have to undergo sublimation, in order to get rid of sulphur and other impurities. In the shops it is usually sold in the form of a white smooth powder, not unfrequently adulterated with chalk or gypsum-an adulteration, however, which can be easily detected by burning a little, when the arsenic volatilises and the additions remain. Arsenious acid, though one of the most virulent poisons, is used in medicine, forming a notable ingredient-for example, in what are called ague drops. It is also employed as an ingredient in Scheele's green and other dyes, in the manufacture of flint-glass, and by candlemakers, to impart to their candles a white and waxy appearance. With sulphur, arsenic forms two compounds, known in commerce by the names of realgar and orpiment; former a red sulphuret found in Bohemia and Saxony, and used as a pigment, as well as in pyrotechnical compositions; and the latter a yellow sulphuret, found native in China, South America, &c. and produced artificially in Saxony, and employed in dyeing and calico-printing. The finer native varieties are reserved for

artists.

the

With respect to the poisonous qualities of arsenic: "When it has been taken in large doses," says Mr Brande, "it produces violent spasmodic pains of the stomach and bowels, attended by a sense of heat and constriction in the mouth and throat, an increased flow of saliva, tightness about the head, itching of the face and neck, and nausea. These symptoms are succeeded by