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bath of molten zinc. The hotter the zinc the thinner the coating, but as a high temperature of the bath is attended with certain objections, it is a See also:

COMMON

common practice to use a moderate temperature and clear off the excess of zinc by passing the plates between rollers. In See also:

NORWOOD

Norwood and See also:

Rogers's See also:

PROCESS

process a thin coating of See also:

TIN (Lat.- stannum, whence the chemical symbol " Sn "; atomic weight =117.6, 0=16)

tin is applied to the iron before it is dipped in the zinc, by putting the plates between layers of granulated tin in a wooden tank containing a dilute See also:

SOLUTION (from Lat. solvere, to loosen, dissolve)

solution of stannous chloride, when tin is deposited on them by galvanic action. In " See also:

COLD (in O. Eng. cald and ceald, a word coming ultimately from a root cognate with the Lat. gelu, gelidus, and common in the Teutonic languages, which usually have two distinct forms for the substantive and the adjective, cf. Ger. Kolte, kalt, Dutch koude

cold galvanizing " the zinc is deposited electrolytically from a bath, preferably kept neutral or slightly acid, containing a 1o% solution of crystallized zinc sulphate, ZnSO4.7H2O. The resulting surface is usually duller and less lustrous than that obtained by the use of molten zinc. Another method of forming a coating of zinc, known as " sherardizing," was invented by Sherard See also:

Cowper-Coles, who found that metals embedded in zinc dust (a product obtained in zinc manufacture and consisting of metallic zinc mixed with a certain amount of zinc See also:

OXIDE

oxide) and heated to temperatures well below the melting point of zinc, become coated with a layer of that See also:

metal. In carrying out the process the articles are placed in an See also:

air-tight See also:

VESSEL (O. Fr. vaissel, from a rare Lat. vascellum, dim. of vas, vase, urn)

vessel with the zinc dust, which must be dry, and subjected to a See also:

HEAT (0. E. haktu, which like " hot," Old Eng. hat, is from the Teutonic type haita, hit, to be hot; cf. Ger. hitze, heiss; Dutch, hitte, heet, &c.)

heat of 250-330°C., the See also:

time for which the See also:

HEATING

heating is continued depending on the thickness of the See also:

DEPOSIT (Lat. depositurn, from deponere, to lay down, to put in the care of)

deposit required and varying from one-See also:

HALF

half to several See also:

HOURS, CANONICAL

hours. If an air-tight receptacle is not available, a small percentage of powdered See also:

CARBON (symbol C, atomic weight 12)

carbon is added to the zinc-dust, to prevent increase in the amount of oxide, which, if See also:

PRESENT

present in excess, tends to make the deposit dull. Galvanized iron by its zinc surface is protected from corrosion by the See also:

WEATHER (O. Eng. weder; the word is common to Teutonic languages; cf. Du. weder, Dan. veir, Icel. ve8r, and Ger. Wetter and Gewitter, storm; the root is wa- to blow, from which is derived " wind ")

weather, though the See also:

PROTECTION

protection is not very efficient in the presence of acid or sulphurous fumes, and accordingly it is extensively employed for roofing, especially in the See also:

FORM (Lat. forma)

form of corrugated sheets. The iron See also:

WIRE (A.S. wir, a wire; cf. Swed. vire, to twist, M.H.G. wiere, a gold ornament, Lat. viriae, armlets, ultimately from the root wi, to twist, bind)

wire used for wire-netting, telegraphic purposes, &c., is commonly galvanized, as also are bolts, nuts, chains and other fittings on See also:

SHIPS

ships.

End of Article: GALVANIZED IRON

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