Zinc, which is commercially known as " Spelter," although it is always brittle when cast, has of late yean taken its place amongst the malleable metals; the early stages of its manufacture into sheet, foil and wire are stated to be conducted at a temperature somewhat above that of boiling water; and it may be afterwards bent and hammered cold, but it returns to its original crystalline texture when romelted. It has been applied to many of the purposes of iron, tinned-iron, and copper; it is less subject to oxidation from the effects of the atmosphere than the iron, and much cheaper, although less tenacious, ductile, or durable than the copper. The sheet metals when bent lengthways of the sheet, (or like a roll of cloth,) are less disposed to crack than if bent sideways, in this respect sine and sheet iron are the worst: the risk is lessened when they are warmed.
The pipes of the great organ in the Town Hall, Birmingham, and of York Cathedral, are made principally of sheet sine.
Zinc is applied as a coating to preserve iron from rust. See the accounts of Mallett's patent zincing process, page 301, and those of Craufurd's galvanised iron, and of More wood's galvanised tinned-iron; tee Notes X and V. page 971-2. Appendix to Vol.II
Zinc mixed with, one-twentieth its weight of speculum metal, may be melted in an iron ladle, and made to serve for some of the purposes of brass such as common chucks. The alloy is sufficient to modify the crystalline character, but reserves the toughness of the zinc; it will not however bear hammering either hot or cold. A. Ross. - Four atoms of zinc and one of tin, or 133.2 and 57.9, make a hard, malleable, and less crystalline alloy.
Biddery ware, manufactured at Biddery, a large city, 60 miles N. W. of Hyderabad in the East Indies, and also at Benares, is said by Dr. Heyne to consist of copper 16 oz., lead 4 oz., and tin 2 oz., melted together; and to every 3 oz. of this alloy, 16 oz. of spelter or zinc are added. The metal is used as an inferior substitute for silver, and resembles some sorts of pewter.
The foregoing alloys are mostly derived from actual practice, and although it has been abundantly shown that alloys are most perfect, when mixed according to atomic proportions, or by multiples of their chemical equivalents, yet this excellent method is little adopted, owing to various interferences.
For example, it is in most cases necessary from an economic view, to mix some of the old alloys, (the proportions of which are uncertain,) along with the new metals. In most cases also unless the fusion and refusion of the alloys are conducted with considerably more care than ordinary practice ever attains, or really demands, the loss by oxidation completely invalidates any nice attempts at proportion; and which proportions can be alone exactly arrived at, when the combined metals are nearly or quite pure.
For the convenience however of those who may desire to pursue the scientific course, the chemical equivalents of the metals upon the hydrogen scale now most usually adopted, are appended to the list of metals, p. 290.
Thus, for mixtures of any metals, say tin and zinc; instead of taking arbitrary quantities, one atom of tin, or 57.9 parts by weight, should be combined with 1, 2, 3, 4, or 5 atoms of zinc, or any multiple of 32.3 parts, and so with all other metals. See Speculum Metal, page 270; Zincing Process, page 301; Article Brass, Suppt. Ency. Brit., etc.