(a) Take 40 gr. silver dust; cream of tartar, 3 dr.; common salt, 2 dr.; and 40 gr. powder of alum. Polish any silver articles with this powder and a soft leather.

(6) Silver nitrate, 30 gr.; common salt, 30 dr.; cream of tartar, 3 1/2 dr. Mix, moisten with water, and apply.

Plated Silver is obtained by rolling together a plate of copper of the first quality, and one of silver; these are either welded, or simply united by placing their hot and clean surfaces together, wetted with a concentrated solution of silver nitrate. The two metals are reduced and drawn out about equally by the pressure of rolls, and long sheets or bands of silvered metal are thus obtained, with which a great many articles may be manufactured. By this mode of operation, a great quantity of material is lost, as the objects have to be cut out from a sheet entirely silvered, and the waste retains a large proportion of that metal; the cut sections present parts without silver, which must be hidden by ledges, or by silvering by another method. There is also the absolute necessity of employing pure copper, which is more costly, less sonorous, and not so tough as its alloys; but the greatest defect of the process is the difference of thickness of the silver, according to the shape of the object. Raised surfaces are the most exposed to friction, and it is just there that the coat of silver is the thinnest; the conditions are reversed with electro-silvering, and the parts in relief receive a more abundant deposit of silver, which is a satisfactory result.

The best plated silver is manufactured by applying upon an ingot of pure copper weighing 9 parts, another ingot of pure silver weighing 1 part, to coat one side only; add another part of silver, if it is intended to coat both sides. The two are rolled together until the desired thickness is obtained. The silver of the plated metal will be bright if the rollers are well polished, and dull with rough rollers. The only solder which does not injure plated silver is tin solder; and when the objects manufactured are required to resist a warm temperature, nuts and screws are employed. The electroplating of old wares made from copper with a covering of silver, is often difficult. Supposing it is required to electroplate an old cruet-stand, the bottom is separated from the wire, either by unsoldering or unscrewing, Smooth by emery cloth, or pumice and water, or by powdered bath-brick brushed over with a hard brush. Spots of verdigris are removed with a few drops of hydrochloric acid. The great difficulty consists in giving a good electro-deposit upon the edges or mounts where there may be some lead or lead solder; apply to such parts, with a rather soft brush, a solution made by dissolving 4 oz. mercury in nitric acid, and adding about 1/2 pint cold water.

This solution is lightly brushed over the lead mounts only; the article and brush are then well rinsed, and the brush and plain water are applied in the same way. The solution of mercury will turn the edges black, or dark grey, but the subsequent brushing will render them bright again. The frame when well rinsed is ready for the depositing bath. If, on its first immersion, any black spots appear, the frame may be removed, again brushed over, and finally returned to the bath. If the edges do not receive the coating of silver as readily as the other parts, the solution may require a little more cyanide, or a greater battery power, or an increase in the surface of the anode. These lead edges may be prepared for receiving the silver deposit by a previous coat of copper applied as follows - The edges are plunged into a solution of copper sulphate, with a little free sulphuric acid in it; then, by touching the lead edge with an iron wire, it is immediately coated with a bright deposit of copper, which is rinsed and becomes a good conductor for the further electro-deposit of silver.

The coating of tin underneath the bottom of cruet frames is very difficult to plate, unless in a solution made expressly for it; therefore it is preferable to remove it either with.abrading materials, or with nitric acid employed with care. This process of depositing copper will be found useful not only for old plated ware, but also for many articles on which are found unruly spots of tin solder.

Ascertaining Weight Of Silver Deposited

(a) The articles are cleansed, dried, and weighed in a scale. However rapidly this may be done, the surface of the copper will be slightly oxidised and tarnished; to recover their former cleanliness, the articles must be plunged into a strong pickle of sulphuric acid, and then into the mercurial solution. „ After rinsing, and immersion in the bath, practical experience will teach ' when it is nearly time to withdraw the ! articles from the solution. They will have to be weighed several times before the intended weight of silver has been deposited.

(6) Cleanse the articles, and put them immediately into the bath, except one, which is treated as above, and used as a test. This piece is now and then removed from the bath to ascertain its increase of weight, and when it has acquired its proportion of silver it is supposed that the other pieces are also finished. Strongly amalgamated articles will not become sensibly oxidised during the drying which precedes their weighing. When the objects have been dried in order to ascertain the proportion of deposited silver, they should not be returned to the bath without having been cleaned in a hot solution of potash cyanide, which dissolves the grease from the handling, and passed again through the solution of nitrate of binoxide of mercury, and rinsed. Alcohol may be substituted for the hot solution of cyanide, but the results are not so sure, and the expense is greater. Both these methods are tedious, and only give approximate results.

(c) Remove one dish of an ordinary pair of scales, substitute for it a metallic frame which supports the articles to be silvered, and communicates through the beam and the column with the negative electrode of a battery; connect the soluble anode with the positive pole. When the articles are suspended to the frame, and are in the bath, the equilibrium of the scale is established by weights upon the other dish; add to this a weight equal to the silver it is desired to deposit. The operation will be finished when the equilibrium of the beam is re-established. This method is not mathematically accurate, but is sufficiently exact for all practical purposes. An "automatic arrangement, by which the electric current may be broken at the time the articles in the bath have received a sufficient deposit of silver, is easily arranged, and saves time and metal.