3711. To Insure Success in the Electroplating Process

3711.   To Insure Success in the Electroplating Process. In order to insure success in silver-plating upon metals and metallic alloys, two solutions of silver are requisite ; the first, to whiten or fix the silver to such metals as iron, steel, britannia metal, and German silver; the second, to finish the work, as any amount of pure silver can be deposited from the second solution.

3712. First, or Whitening Solution

3712.    First, or Whitening Solution. Dissolve 21/2 troy pounds cyanide of potassium, 8 ounces carbonate of soda, and 5 ounces cyanide of silver in 1 gallon rain or distilled water. This solution should be used with a compound battery of 3 to 10 pairs, according to the size of the work to be plated. The use of this solution will insure the adhesion of silver to all kinds of brass, bronze, type metal, etc., without employing mercury, the frequent use of which is injurious to the health of the operator.

3713. Second, or Finishing Solution

3713.    Second, or Finishing Solution. Dissolve 41/2 troy ounces cyanide of potassium, and l1/2 ounces cyanide of silver, in 1 gallon rain or distilled water. This solution should be used with one large cell of Smee's battery, observing that the silver plate is placed as near the surface of the articles to be plated as possible.

3714. Boettger's Test for the Silver on Silver-Plated Metals

3714.    Boettger's Test for the Silver on Silver-Plated Metals. The test fluid consists of a saturated solution of bichromate of potassa in nitric acid, specific gravity 1.2. Any dirt or varnish having been removed by strong alcohol from the metallic surface to be tested, a drop of the test fluid is applied to it by means of a glass rod, and immediately afterwards washed off with some cold water. If pure silver is present (as regards silver coins, these are left in contact with the test fluid for a greater length of time), there will appear clearly a blood-red colored mark (chromate of silver). Upon German silver the test liquid appears brown, but after washing with water the blood-red colored mark does not appear; the so-called britannia-metal is colored black; on platinum no action is visible ; metallic surfaces coated with an amalgam of mercury yield a reddish speck, which, however, is entirely washed off by water; on lead and bismuth the test liquid forms a yellow-colored precipitate; zinc and tin are both strongly acted upon by this test liquid, which, as regards the former metal, is entirely removed by water, while, as regards the latter, the test liquid is colored brownish, and addition of water produces a yellow precipitate which somewhat adheres to the tin.

3715. Plating on Iron or Steel

3715.    Plating on Iron or Steel. Take 2 quarts rain water, dissolve 2 pounds cyanide of potassium, and filter. In order to plate steel or iron, dip it into pure sulphuric acid for one minute, then clean with pumice stone, and brush; rinse, and hang in solution of cyanide of potassium for three minutes, or until it becomes white; then hang in silver solution until plated heavy enough. (See No. 3698 (To Make Silver Solution).)