An excellent black varnish for zinc or tin is composed as follows: Equal parts of chlorate of potassium and blue vitriol (sulphate of topper) are dissolved in 36 times as much warm water, and the solution is allowed to cool. If the sulphate of copper contains iron, it is precipitated as a hydrate oxide, and can be removed by decanting or filtering. The metal pieces to be coated are then immersed in the solution, or the solution may be flowed on, and allowed to remain a few moments, until the metal becomes black. Then rinse off with water and let dry. Even before it is dry the black coating adheres to the article, so that it may be wiped with a cloth. If copper-colored spots appear during the operation, the same solution should be applied a second time in the same manner. On rubbing, the coating acquires a glittering blue appearance, like indigo, but this disappears on applying a few drops of linseed oil, varnish, or "wax-milk," and the metal then has a deep black color and gloss. The "wax-milk" above referred to may be prepared by boiling 1 part yellow soap and 5 parts Japanese wax in 21 parts of water until the soap dissolves. When cold it has the consistency of a salve, and will keep in a closed vessel for an indefinite time. It can be used for polishing carved wood and for waxing ball-room floors, as it is cheaper than the solution of wax and turpentine, and does not stick or have any disagreeable odor.