3668. Improved Liquid for the Galvanic Battery

3668.     Improved Liquid for the Galvanic Battery. Mr. Victor Barjon's new battery liquid is made by mixing a solution of bichromate of potash with a little lime, and with sulphuric acid. Ho puts 2 pounds bichromate of potash into a gallon of boiling water, and lets the solution cool down to 68°, and adds 2 ounces of lime. After stirring, he adds sulphuric acid until the gravity reaches 35° Baumé. Then, having stirred the whole, he lets it stand for 24 hours, when it is ready for use.

3669. Electrotyping by the Single Cell Process

3669.     Electrotyping by the Single Cell Process. This is an adaptation of Daniell's cell to the purposes of electrotyping, and dispenses with any separate decomposing cell; in fact it is a galvanic battery and a decomposing cell combined in one, and is useful, for small objects, from its simplicity. About 2/3 fill a large jar (a preserve jar without any neck is best), with a solution of sulphate of copper (see No. 3661 (Solution of Copper for Electro-typing)); insert in this a small tubular porous vessel of about the same height as the jar (these porous tubes can be found at any store where chemical apparatus is sold), and pour into it a mixture of 21 parts water and 1 part sulphuric acid, until the diluted acid in the porous tube stands at the same level as the sulphate of copper solution outside it. To one end of a piece of copper wire fasten a strip of amalgamated zinc (see No. 3662 (To Amalgamate Zinc)), which is to be inserted in the porous tube; to the other end of the wire attach the object to be electro typed, properly prepared (see No. 3689 (To Prepare Non-Metallic Moulds to Receive Deposit)), and place it in the copper solution, with its face parallel to the zinc plate, and about 1/2 an inch from the side of the porous tube. In about 24 hours the deposit of copper will be of about the thickness of a card, and may be taken off. "When not in use, the zinc should be taken out, washed and dried; and when in use must on no account touch the bottom or any other part of the porous tube. It is a good plan to give the wire one twist round a stick of wood, laid across the top of the tube, so as to suspend and support the zinc. A few crystals of sulphate of copper, enclosed in a piece of lawn or net, should be hung from the edge of the vessel just below the surface of the copper solution, to replace the copper that deposits on the object being electrotyped, and prevent the solution from becoming weaker.

3670. To Coat Silver with Platina

3670.     To Coat Silver with Platina. This is effected by the one cell process, substituting for the sulphate of copper solution, water acidulated with sulphuric acid, and containing a little chloride of platinum. The silver is first roughened on the surface by applying strong nitric acid, and washed; it is then attached to the end of the wire leading from the zinc plate in the porous cell, and immersed in the platinum solution exactly as if it were a medal to be electrotyped, until the surface is covered with a dark and granular deposit.