3645. To Tin Copper Tubes

3645.     To Tin Copper Tubes. W. Wollweber recommends for still-worms copper tubes tinned inside in the following manner : To a solution of Rochelle salts a solution of salts of tin is added ; a precipitate of stannous tartrate is formed, which is washed and then dissolved in caustic lye. The copper tube, which has first been rinsed with sulphuric acid and then washed, is then filled with the alkaline solution, warmed a little, and touched with a tin rod, which causes the deposition of a coat of metallic tin.

3646. To Tin a Worn Copper Kettle

3646.    To Tin a Worn Copper Kettle.

A thick coating maybe obtained by preparing a tinning solution of zinc dissolved in muriatic acid, making the solution as thick or heavily charged with zinc as possible, adding a little sal-ammoniac. Clean the inside of the kettle, place it in a charcoal fire until a piece of block tin placed inside melts, then rub the melted tin with some of the tinning solution, quickly on the copper surface, by means of a ball of oakum and a little powdered resin; the tin will readily adhere. Wrought iron and steel may be tinned in the same manner.

3647. To Tin a Copper Vessel

3647.    To Tin a Copper Vessel. Boil the copper vessel with a solution of stannate of potassa mixed with tin borings, or boil with tin filings and caustic alkali or cream of tartar. In a few minutes a layer of pure tin will bo firmly attached.

3648. To Tin Cast Copper or Brass

3648.    To Tin Cast Copper or Brass. Make a saturated solution of oxide of tin (tin putty), in potash lye; add to the solution some tin filings or shavings; make it as hot as possible; then introduce the brass or copper and it will be tinned in a few seconds.

3649. To Galvanize Iron

3649.    To Galvanize Iron. The difference between galvanized plates, so-called, and "sheet-tin," is, that the latter is sheet-iron covered with a thin coating of block-tin, while the former is sheet-iron covered with a thin coating of zinc. To effect the latter result, the iron plates are first immersed in a cleansing bath of equal parts of sulphuric or muriatic acid and water, used warm. (See No. 3266 (To Remove Rust from Iron).) They arc then scrubbed with emery or sand, to clean them thoroughly and detach all scales, if any are left; after which they are immersed in a preparing bath of equal parts of saturated solutions of chloride of zinc and chloride of ammonium, from which bath they are directly transferred to the fluid metallic bath, consisting of 20 chemical equivalents of zinc to 1 of mercury; or, by weight, 640 pounds of zinc to 106 of mercury, to which are added from 5 to 6 ounces of sodium. As soon as the iron has attained the temperature of this hot fluid bath, which is only 680° Fahr., it may bo removed, and will then be found thoroughly coated with zinc. Care must bo taken not to leave the plates too long immersed in this bath, as its affinity for iron is such that they may become dissolved. This is the case with thin plates of wrought-iron, which, even when 1/8 inch thick, may be dissolved in a few seconds. It is safe, therefore, to let the bath previously act on some wrought-iron, so that it dissolves a portion of it, in order to satisfy its inconveniently great affinity for this metal.