A metal of a white colour, intermediate between silver and lead. It is considerably harder than lead; scarcely at all sonorous; very malleable, being capable of extension, under the hammer, to about a two-thousandth part of an inch in thickness. The ordinary tinfoil is about a one-thousandth part of an inch thick. Tin has a slight unpleasant taste, and emits a peculiar smell when rubbed. Specific gravity, 7.291. It is very flexible, producing a remarkable crack ling noise when bended, the loudness of which is a common, though not very accurate test of its purity. Tin melts at 442° Fahr.; when fresh cast, or fresh scraped, it is very brilliant, but it gradually loses its lustre by exposure to the air, and acquires a greyish-white tint, which does not sensibly change. Like lead, when heated nearly to fusion, it is brittle, and may be easily broken up by a hammer, when it exhibits a grained or fibrous texture. It may also be reduced to powder by agitation, at the period of its transition from the solid to the fluid state.
There are several kinds or qualities of tin. The Cornish block tin is usually in blocks of about three cwt. each; which are, however, run into smaller masses, of 30 or 40 lbs. each, for the convenience of trade. The common block tin is contaminated with a minute quantity of other metals, generally copper, to the extent of about a thousandth part. "Refined block-tin" is in blocks of tin melted into long narrow sticks, of a few ounces each. The "grain tin" is the purest of the several English kinds, being obtained from the pure oxide of tin of the steam-works of Cornwall. It is first cast into blocks of about 120 lbs. each, and afterwards melted, so as to separate it into fragments resembling rocks; which is produced by letting the metal fall. when barely fluid, from a great height. The tin imported from the East Indies, particularly Malacca, is esteemed very pure, and considered the best for organ pipes, and some other uses.
The tin ore of Cornwall, obtained from the mines, is stamped to reduce it into fragments, then washed, to separate the earthy matter, and afterwards roasted in a reverberating furnace; which process is repeated until the assay shows it to contain at least half of its weight of metal, when it is sold to the smelters. In this state it is mixed with culm and slaked lime, well moistened, and then smelted in a reverberating furnace, capable of reducing about 7 cwt. at a time. A given weight of tin, produced from Cornish ore, consumes about double its weight of coal in the operations of roasting and smelting. Between three and four thousand tons of tin are produced annually from the mines of Cornwall. Chaptal says, that if tin be kept in fusion in a lined crucible, and the surface be covered with a quantity of charcoal, to prevent its calcination, the metal becomes whiter, more sonorous, and harder, provided the fire be kept up for eight or ten hours.
Mercury dissolves tin with great facility, and in all proportions. To make this combination, heated mercury is poured on melted tin; the consistence of the amalgam differs according to the relative proportions of the two metals.
Nickel, united to tin, forms a white and brilliant mass. Half a part of tin, melted with two parts of cobalt, and the same quantity of muriate of soda, furnished Beaume with an alloy in small close grains of a light violet colour. Equal parts of tin and bismuth form a brittle alloy, of a medium colour between the two metals, and the fracture of which presents cubical facets.
Antimony and tin form a white and brilliant alloy, which is distinguished from other alloys of tin by its possessing a less specific gravity than either of the two metals by which it is formed.
. In combining arsenic with tin, precautions must be taken to prevent the arsenic from escaping by volatilization. Three parts of tin may be put into a retort, with one-eighth part of arsenic in powder; fit on a receiver, and make the retort red hot; very little arsenic rises, and a metallic lump is found at the bottom, containing about one-fifteenth part of arsenic; it crystallizes in large facets, is very brittle, and hard to melt.
If tin be kept in fusion with access of air, its surface is speedily covered with a greyish pellicle, which is renewed as fast as it is removed. If this grey oxide be pulverized and sifted, to separate the uncalcined tin, and calcined again for several hours, under a muffle, it becomes the yellow oxide of tin, called among artizans putty of tin, and extensively used in polishing of glass, steel, and other hard bodies.
A white oxide of tin is used in forming the opaque kind of glass called enamel. This composition is made by calcining 100 parts of lead and 30 parts of tin, in a furnace, and then fluxing these oxides with 100 parts of sand, and 20 of potass. This enamel is white, and is coloured with metallic oxides.
All the mineral acids dissolve tin, and it may be precipitated from its solutions by potass; but an excess of potass will re-dissolve the metal. Nitro-muriate of gold is a test of tin in solution, with which it forms a fine purple precipitate.
The sulphuric acid dissolves tin, whether concentrated or diluted with water; part of the acid is decomposed, and files off in the form of sulphurous acid gas. Heat accelerates the effect of the acid. Tin, dissolved in the sulphuric acid, is very caustic.
The solution of tin in the nitric acid is performed with astonishing rapidity, and the metal is precipitated almost instantly in the form of a white oxide. If this acid be loaded with all the tin it is capable of calcining, and the oxide be washed with a considerable quantity of distilled water, a salt may be obtained by evaporation, which detonates alone in a crucible well heated, and burns with a white and thick flame, like that of phosphorus. The nitric acid holds but a very small quantity of tin in solution, and when evaporated for the purpose of obtaining crystals, the dissolved portion quickly precipitates, and the acid remains nearly in a state of purity. Nitric acid, much diluted, holds rather more tin in solution, but lets it fall by standing, or by the application of heat.
The muriatic acid dissolves tin, whether cold or hot, diluted or concentrated. If fuming, and assisted by a gentle heat, the addition of the tin instantly causes it to lose its colour and property of emitting fumes, and a slight effervescence takes place. The acid dissolves more than half its weight of tin; the solution is yellowish, of a fetid smell, and affords no precipitate of oxide, like the sulphuric and nitric acids.
The oxy-muriatic acid dissolves tin very readily, and without effervescence, because the metal quickly absorbs the superabundant oxygen from the acid, and requires'no decomposition of the water to effect its oxidation.
Nitro-muriatic acid, made with two parts of nitric acid, and one of muriatic acid, dissolves tin with effervescence. It is the solution of tin in this acid which the dyers employ to heighten the colour of their scarlet dyes. It is prepared by adding small portions at a time, of tin, to the common aquafortis of commerce: when the appearance of oxide is observed at the bottom of the jar, muriate of soda is added, by which its solution is effected. If the colour imparted by this solution is not bright, a little nitrate of potass is added to it
The acetous, and most other vegetable acids, have some action upon tin, particularly when aided by a gentle heat; but the solutions thus obtained are not used in the arts. Tin decomposes the corrosive muriate of mercury. It is for this purpose amalgamated with a small portion of mercury and this amalgam, being first triturated in a mortar with the corrosive muriate, the mixture is then distilled by a gentle heat A colourless liquor first passes over, and is followed by a thick white vapour, which issues with a kind of explosion, and covers the internal surface of the receiver with a very thin white crust. The vapour becomes condensed into a transparent liquor, which continually emits a thick, white, and very abundant fume. It was formerly called the fuming liquor of Libavius, and is the combination of the muriatic acid and tin.
Tin has a strong affinity for sulphur; the sulphuret of tin may be formed by fusing the two substances together: it is brittle, heavier than tin, and not fusible. It has a blueish colour, a lamellated texture, and is capable of crystallizing.
The white oxide of tin combines with sulphur, and forms a compound called aurum musivum, or mosaic gold, which is much used for giving to plaster-of-Paris the resemblance of bronze, and improving the appearance of bronze itself. It is also occasionally used to increase the effects of electrical machines. See Aurum Musivum.
Tin possesses the property in a remarkable degree of promoting the fusibility of other metals, with which it is mixed. Two parts of lead, and one of tin, which forms the best plumber's solder, melt at a temperature of little more than 300 Fahr.; although the melting point of tin alone is 440o, and that of lead 612o. One part of tin, and two of lead, which forms the inferior plumber's solder, melt at a lower temperature than the first-mentioned proportions, notwithstanding the increased quantity of the less fusible metal. Eight parts of bismuth, (which melts per se at 480°,) five of lead, and three of tin, fuse at a heat below that of boiling water. It is this alloy of which tea-spoons are sometimes made, to surprise those who are ignorant of their nature, by their melting in a cup of hot tea.
The uses of tin are so very numerous, and so well known, as not to need detailing. We shall advert to only a few; viz. the fabrication of boilers and kettles for dyers' use; the worms of stills; the drawing of pipes, (erroneously called pewter) for gas conduits, for beer, wine, vinegar, and other acetous liquids, which have no action upon pure tin: if the tin were alloyed, it could not be drawn into sound pipes. Tin forms the principal ingredient in pewter of all qualities, and enters largely into the greater part of the white alloys in such extensive use. Immense quantities of tin are used in the fabrication of tinned iron plates, improperly called tin-plates. We may also here notice a new and most important application of this pure metal, (under a patent granted to Mr. John Warner, jun. founder, etc, of Cripplegate, London,) which is that of giving a perfect and beautiful coat of tin to lead pipes, which thus possess the valuable qualities of both metals; viz. the cheapness and flexibility of lead, and the purity and indestructibility of tin.