Zinc-coating
Copper and brass articles may be permanently coated with a layer of pure zinc by boiling them in a solution of chloride of zinc, with an excess of zinc-turnings present in the solution.
Gray-iron castings may be coated or galvanized by first cleaning them by abrasion with sand in a tumbling-barrel, then heating and plunging them separately, while hot, in a liquid composed of hydrochloric acid 10 lbs., and sufficient sheet lead to make a saturated solution. In making this solution, add sulphate of ammonia 1 lb., when the evolution of gas has ceased. If the castings are hot enough after dipping them in this solution they will dry almost instantly, leaving a crystallized surface of zinc. They must now be placed in a bath of melted zinc over which, after skimming, some powdered sal-ammoniac has been thrown to prevent further oxidation. Small articles can be lowered into the bath in a wire basket, lifted out, the superfluous metal shaken off, and then cast into water.