GALVANIZED IRON, sheet iron having its surface covered with a thin coating of zinc. In spite of the name, galvanic action has often no part in the production of galvanized iron, which is prepared by dipping the iron, properly cleaned and pickled in acid, in a 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 common practice to use a moderate temperature and clear off the excess of zinc by passing the plates between rollers.
The light copper alloys, in which the proportions just given are practically reversed, are of considerably less utility, for although they are fairly strong, they lack power to resist galvanic action.
Chemical reagents are sometimes added - lime or sulphuric acid, to neutralize an excess of acid or alkali; copper sulphate, to form cuprous chloride with sodium chloride; and iron and zinc, to make the galvanic action more energetic and reduce the consumption of iron.
About this time a voluntary subscription among the members of the Royal Institution put him in possession of a new galvanic battery of 2000 double plates, with a surface equal to 128,000 sq.
If it be exposed to damp, to sea-water or to corrosive influences of any kind in contact with another metal, or if it be mixed with another metal so as to form an alloy which is not a true chemical compound, the other metal being highly negative to it, powerful galvanic action will be set up and the structure will quickly deteriorate.
Hankel still further improved the dry pile electrometer by giving a slow motion movement to the two plates, and substituted a galvanic battery with a large number of cells for the dry pile, and also employed a divided scale to measure the movements of the gold-leaf (Pogg.
In Norwood and Rogers's process a thin coating of 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 solution of stannous chloride, when tin is deposited on them by galvanic action.
His first communication to the Royal Society, read in June 1801, related to galvanic combinations formed with single metallic plates and fluids, and showed that an electric cell might be constructed with a single metal and two fluids, provided one of the fluids was capable of oxidizing one surface of the metal; previous piles had consisted of two different metals, or of one plate of metal and the other of charcoal, with an interposed fluid.
In steam boilers artificial galvanic couples are often set up by the suspension of zinc plates in the boiler, so that the corrosion of the zinc may preserve the steel boiler plates from waste.
C. Oersted, of the action of the galvanic current on a magnet.