3612. Spencer's Method of Silvering Wood

3612.    Spencer's Method of Silvering Wood. The first operation is to take strong alcohol or spirits of turpentine in a glass vessel, and add to it a piece of phosphorus (a common corked phial will answer the purpose); the vessel must now be placed in hot water for a few minutes, and occasionally shaken; by this means the alcohol will take about 3 per cent, of its bulk of phosphorus.

Next procure a weak solution of nitrate of silver, place it in a flat dish or saucer; the face of the wood must now be dipped in this solution, and let it remain a few minutes to allow capillary attraction to draw it into the wood. This operation being performed, a small portion of the solution of phosphorus must be placed in a capsule or watch-glass, and this placed on a sand-bath, that it may gradually evaporate. The wood must now be held with its surface over the vapor, and an immediate change takes place; the nitrate of silver is decomposed, and gives place to metallic silver. "When the material to be acted on is not very large, fasten it to the top of a bell-glass receiver with a bit of pitch or cement, and place this over the capsule on the sand-bath; the phosphorus vapor is by this means equally diffused, and not dissipated. A solution of phosphorus in sulphuric ether also answers; and a solution of gold (chloride) may be used. This elegant process, as applied to wood and those substances which may be wetted with the solution of nitrate of silver, answers perfectly; but it is obviously limited in its application to those substances which will absorb an aqueous solution.

3613. Silvering Glass

3613. Silvering Glass. Two distinct methods are adopted for this purpose. The one falsely called silvering, consists of the application of a layer of an amalgam of tin, or similar alloy, to the surface of the glass {see No. 3614 (To Silver Looking-Glasses)), the other is a coating of real silver, precipitated from a solution of that metal. {See Nos. 3615 (To Silver Glass), etc..)

3614. To Silver Looking-Glasses

3614. To Silver Looking-Glasses. This is usually done by coating the glass with an amalgam. For this purpose a large, perfectly flat stone table is provided; upon it is evenly spread a sheet of tin foil without crack or flaw; this is covered uniformly to the depth of 1/8 inch with clean mercury. The plate of glass, perfectly cleansed from all grease and impurity, is floated on to the mercury carefully, so as to exclude all air bubbles. It is then pressed down by loading it with weights in order to press out all the mercury which remains fluid, which is received in a gutter around the stone. After about 24 hours it is raised gently upon its edge, and in a few weeks it is ready to frame. It is said to be desirable to have the lower end of the glass, from which the mercury was drained, at the bottom of the frame. To convex and concave mirrors the amalgamated foil is applied by means of accurately fitting plaster moulds. The interior of globes is silvered by introducing a liquid amalgam, and turning about the globe till every part is covered with it, {See Nos. 3538 (Amalgam for Silvering the Insides of Convex Mirrors, Glass Globes, etc.) and 3545.)