(a) 15 grm. silver nitrate are dissolved in 250 grm.water, and 30 grm. potassium cyanide are added; when the solution is complete, the liquid is poured into 750 grm. water, in which 15 grm. common salt have been previously dissolved. The cast iron intended to be silvered by. this solution should, after having been well cleaned, be placed for a few minutes in a bath of nitric acid of 1.2 sp. gr., just previous to being placed in the silvering fluid.

(b) Polish the surface very clean and level with a burnisher; then expose it to a blueing heat; a leaf of silver is to be properly placed and carefully burnished down. This is repeated until sufficient leaves are applied to give the silver a proper body.

(c) By solder. Slips of thin solder are placed between the iron and silver, with a little flux, and secured together by binding wire. Then place in a clear fire until the solder melts; when it is taken out, on cooling, it will adhere firmly.

(d) By tinning the iron first, and uniting the silver by means of slips of rolled tin, brought into fusion in a gentle heat.

(e) A manufacturer in Vienna employs the following process for silvering iron. He first covers the iron with mercury, and silvers by the galvanic process. By heating to 570° F., the mercury evaporates and the silver layer is fixed. Ironware is first heated with dilute hydrochloric acid, and then dip-ped in a solution of mercury nitrate, being at the same time in communication, with the zinc pole of an electric battery, a piece of gas carbon or platinum being used as an anode for the other pole. The metal is soon covered with a layer of quicksilver, and is then taken out and well washed and silvered in a silver solution. To save silver, the ware can be first covered with a layer of tin; 1 part cream of tartar is dissolved in 8 of boiling water, and one or more tin anodes are joined with the carbon pole of a Bunsen element. The zinc pole communicates with a well-cleaned piece of copper, and the battery is made to act till enough tin is deposited on the copper, when this is taken out and the ironware is put into its place.

The ware thus covered with tin chemically pure and silvered, is much cheaper than any other silvered metals.

(f) De Villiers has invented a metallic alloy for silvering. It consists of 80 parts tin, 18 of lead, and 2 of silver, or 90 of tin, 9 of lead, and 1 of silver.

The tin is melted first, and when the bath is of a brilliant white the lead is added in grains, and the mixture is stirred with a stick of pine wood, the partially melted silver is added, and the mixture is stirred again. The fire it then increased for a little while, until the surface of the hath assumes a light yellow colour, when it is thoroughly stirred up and the alloy is cast in bars.

Whenever there is a choice between iron and steel, in making any article, the best quality of steel is to be preferred. The operation is then carried out in the following manner; -

The article, a knife blade for example, is dipped in a solution of hydrochloric or sulphuric acid (1-10 parts acid in 100 of water). After taking it out of this pickle, it is immediately rinsed with clean water, then dried and rubbed with a piece of soft leather or dry sponge, and finally exposed to a heat of 158°-176° F., for 5 minutes in a muffle. The object of this is to prepare the iron or steel to receive the alloy, by making the surface porous or covered with small microscopic holes. If the iron is not very good these holes are much larger, and frequently flaws and bad places are disclosed, which make the silvering more difficult. With steel the process goes on very regularly.

The article is warmed to 122°-140° F., and dipped in the bath of the above described alloy, which is melted by a gentle fire of graphite or refractory clay. The bath must be perfectly fluid, and is stirred with a stick of pine or poplar; the surface of the bath must have a fine white silver colour. Under these circumstances the object thus prepared quickly takes up the alloy, which penetrates the porous surface. For a knife blade an immersion of 1-2 minutes is sufficient to cover it; larger articles require 5 minutes' immersion. -After taking it out of the bath, it is dipped in cold water, or treated in such a way as to temper it, if tempering is necessary. If it is left too long in cold water, it frequently becomes brittle, but this evil can be avoided by a little experience. It is then only necessary to rub it off dry and polish without heating it.

Articles treated in this manner look like silver, and ring like it top, and withstand the oxidising action of the air. To protect them from the effect of acid liquids like vinegar, they are dipped in a bath of amalgam, composed of 60 parts mercury, 39 of tin, and 1 of silver. It is then dipped warm into melted silver, or electro-plated with silver to give it the silvery look. The method of polishing will depend on the shape of the object. This kind of silvering is said to be very durable, and even resist gentle filing. The cost of the process is comparatively small.