1. Saturated solution of sulphate of copper 2 parts, sulphuric acid 2 parts, water 6 or 8 parts. 2. Mr. Walker directs 2 measures of a saturated solution of sulphate of copper, and 1 measure of acidulated water (1 part of sulphuric acid to 9 of water), 3. Robell's solution consists of 2 parts of a saturated solution of sulphate of copper, and 1 part of a saturated solution of Glauber's salt, to which as much sulphate of copper has been added as it will take up.

2. Gold Solution. Dissolve 2 oz. of cyanide of potassium (prepared by Lieeig's method) in a pint of warm distilled water, add 1/4 oz. of oxide of gold, and agitate together.

3. Silver Solution. Dissolve 2 oz. of Liebig's cyanide of potassium in a pint of distilled water; add 1/4 oz. of moist oxide of silver (precipitated by lime-water from a solution of the crystallized nitrate), and agitate together till the oxide is dissolved.

4. Solution in which Steel Articles are dipped before Electroplating them. Nitrate of silver 1 part, nitrate of mercury 1 part, nitric acid (sp. gr. 1.384) 4 parts, water 120 parts.

5. Solution, or Pickle, for Immersing Copper Articles in before Electroplating. Sulphuric acid 6.4 parts, water 64, nitric acid 32. hydrochloric acid 1: mix. The article, free from grease, is dipped in the pickle for a second or two. See Gildin'G, Silvering, Electro-Brassing, etc.

Solution for Mullins' Voltaic Battery, In contact with the Zinc: 1 part of sal ammoniac to 5 of water. In contact with the Copper: a saturated solution of sulphate of copper. M. Bachhoffner uses a saturated solution of common salt and a saturated solution of sulphate of copper.