TILT-HAMMER. A heavy hammer used in iron-works, which is worked by machinery, impelled either by a water wheel or a steam-engine. Such hammers are extensively used in the manufacture of iron and steel. The hammer used for hammering the blooms of iron, is usually called a lift or helve hammer, and is some times of the enormous weight of six tons. The tilt-hammer, properly so called, is of lighter dimensions, and is worked with greater rapidity ; a specimen of the kind usually employed in the manufacture of steel, and.•in the forging of anchors, &c., is represented in the accom panying engraving. a, is the shank or helve, usually formed of timber, and sometimes of wrought iron ; it is hung upon an axis at about one-third of its length, and is worked by a series of re volving cams or tappets c c, fixed into the circumference of the cam-ring b, mounted upon the shaft of esteem-engine or water-wheel. These cams act succes sively by depressing the shorter limb of the shank a, until, by the continued re volution, it is disengaged, and the oppo site extremity, armed with a heavy cast iron hammer d, descends with consider able force upon the anvil e. Thus a re petition of blows is kept up as long as may be required.
TIN, is rather a scarce metal, found in few parts of the world in any quantity. Cornwall is its most productive source ; it also occurs in the mountains between Gallicia and Portugal, and in those be tween Saxony and Bohemia, and in Cali fornia. Tin has also been brought from the peninsula of Malacca in India, Borneo, and from Chili and Mexico. There are only two ores of tin, the native peroxide, and the double sulphuret of tin and cop per : the latter, sometimes called bell metal ore, is extremely rare ; and it is ex clusively from the former that the com mercial demands are supplied. In Corn wall the native peroxide, or tin stone (which is usually blended with oxides of iron and manganese), occurs in veins, and in loosegrains and nodules in alluvial soil ; the latter is called stream tin, and from it the purest metal is obtained. The ore is reduced by a very simple pro cess; it is ground, washed, and roasted in a reverberatory furnace ; it is then mixed with charcoal or coke of coal and limestone, and strongly heated, so as to bring the whole into fusion, which is kept up for eight or ten hours : the lime combines with the earthy matters of the ore into a fusible slag, while the coal re duces the oxide to a metallic state, and the fused metal is drawn out at the bot tom of the furnace into a clay mould. In this impure state it is exposed to a heat just sufficient to melt the pure tin, which runs off into a kettle, while the less fusible impurities remain behind: in the kettle, the tin is kept in fusion, and agitated by plunging pieces of wet charcoal into it, which causes a quantity of dross to rise to the surface, where it is skimmed off, and the purified metal is then cast into blocks of about 8 cwt. each.
The stream tin is smelted by charcoal ; and the mass of grain tin obtaired by such reduction is heated and let fail from a height, by which it splits into masses of a columnar fracture, which character izes the pure metal.
Pure tin is a white, brilliant metal. It has a slight taste and smell when rubbed, and its hardness is intermediate between that of gold and lead. Its specific gravity is 7/. It is very malleable; and one of its most useful forms is that of foil, which is made by beating : it is about a thousandth of an inch in thickness. Its ductility and tenacity are inferior to most of the other malleable metals. A tin wire 78 thousandths of an inch in diame ter will not support more than 88 pounds without breaking. It produces a pecu liar crackling noise when beat. Ex posed to air, it soon becomes superficially oxidized ; and when melted, successive films of a gray powder form upon its sur face. The temperature at which it melts
is about 442°. At a white heat it takes fire, and burns with a bright flame. The equivalent of tin is 58. It forms two oxides. The protoxide is thrown down by alkaline carbonates from an aqueous solution of protochloride of tin ; and when dried and heated out of the con tact of air, its water is expelled, and it remains in the form of a dark substance, of the specific gravity 6.6. It burns like tinder, and becomes converted into the peroxide. It is soluble in sulphuric and hydrochloric, and in dilute nitric acid, and in the pure fixed alkalies. Its salts have a strong attraction for oxygen, and easily pass into persalts ; so that it is a powerful deoxidizing agent, and is often used as such in some of the chemical arts. When a solution of protochloricle of tin is dropped into a solution of perchioride of gold, a purple precipitate, called, from its inventor, purple Cassius, is thrown down it appears to be a compound of peroxide of tin with protoxide of gold, and its formation depends upon the de oxidizing power of the solution of tin. When tin toil is put into nitric acid, there is violent action, attended by the decom position of the acid and the peroxidizc ment of the tin, which is thus converted into a white powder : this, when ednl corated and dried at a red heat, acquires a yellow tint. It does not easily form permanent compounds with the acids; but it unites with the pure alkalies, and forms soluble compounds, which have sometimes been called stannates, and the peroxide itself stannic acid. The two oxides of tin are respectively composed of 58 tin and 8 oxygen, and 58 tin and 16 oxygen : their equivalents, therefore, are 66 and 74. Tin and chlorine also com bine in two proportions : theprotockloride of tin is formed by passing hydrochloric acid gas over metallic tin gently heated in a glass tube, or by heating a mixture of equal weights of tin filings and calo mel, when it remains, after driving off the mercury, in the form of a gray solid, fusible at a red heat, and volatile at higher temperatures. Its aqueous solu tion is commonly termed protosnuriate of tin. When tin foil is heated in excess of gaseous chlorine, or when 1 part of tin filings is mixed with 3 of corrosive sub limate and heated, a volatile liquid dis tils over, which is perchloride of tin, and its aqueous solution forms the perrnieriate. Exposed to air, it is decomposed by the aqueous vapor of the atmosphere, and exhales dense white fumes : hence called, after its discoverer, fuming liquor of Lihavins. Both the protomuriate and permuriate of tin are used by dyers and calico-printers. The former is prepared by heating granulated tin in strong hy drochloric acid, as long as hydrogen con tinues to be evolved ; the latter, by gradually dissolving granulated tin in a mixture of two parts by measure of hy drochloric aeid, one of nitric acid, and one of water. These chlorides of tin are respectively composed of 58 tin and 86 chlorine, and 58 tin and 72 chlorine, and are therefore represented by the equiva lents 94 and 130.
When melted tin and sulphur are brought together, a black protosulphyret of tin is formed. The bisulphuret of tin is a yellow glistening substance, some times called Mosaic gold (avrunt musi tam), and used in ornamental japan work. It is prepared by heating in n glass retort 2 parts of peroxide of tin, 2 of sulphur, and I of sal ammoniac, and maintaining a low red bent till sulphurous acid ceases to be evolved. The sulphuret and bisulphuret of tin are constituted of 58 tin and 16 sulphur, and 58 tin and 39 sulphur ; and have, therefore, the equiv alents 74 and 80.