GALVANIZING DAGUERREOTYPE PLATES.

The Battery. The best way is to purchase a good Daniel's Battery. Price $2 00. To be had at any of the dealers.

For the benefit of those who cannot procure one, I would give the following directions for making one: Procure a copper cup, (sheet copper) 6 inches high, and 4 inches in diameter; also a cup of porous earthenware, (a small unglazed flower pot answers,) or a leather cup made water tight by sewing, or even a cylinder of porous wood, (say maple or ash,) 3 inches diameter, and about 6 inches high. This is to stand in the centre of the copper cup. Now, procure a solid cylinder of zinc, 6 inches high and 1 inch diameter. This is to stand in the centre of the porous cup. Fastened to the upper end of the zinc cylinder there should be a copper wire, pretty thick. It should be held by a screw, or soldered on, and previous to the fastening, both the wire and zinc should be made clean and bright, that there may be a perfect connection. A similar wire is to be fastened, in the same way, to the upper rim of the copper cup. Let these wires be about 6 inches long. To the end of the one coming from the copper fasten a plate of pure silver, about as large as a quarter plate, unless you wish to galvanize whole plates, in which case the silver plate must be larger, say, the size of a half plate. For small plates a silver dollar, enlarged to twice its size by hammering, will answer, but is not so good. To hammer it, it must be first heated, red hot, and allowed to cool slowly. This plate is to be immersed in the silver solution, described below, near the side of the solution jar. The other wire must be bent at the end like a hook, to receive the catch. This catch may be a piece of copper wire about 4 inches long, hooked at one end, and having several turns at the other end, to strengthen it. Between these turns the Daguerreotype plate, well polished, is inserted, as in a sort of jaw. The wire holding the catch should be so bent that the Daguerreotype plate will stand from one to three inches from, and face the annode, or silver plate.

Let the silver solution be well stirred, just before immersing a plate; then, blowing away the froth and scum, immediately dip the plate, and hang it on the wire. Let it remain until it takes on a deep blue color, take it out, grasp it with the plyers, rinse it freely with clean water, and dry it carefully with a spirit lamp. Buff again to a polish, galvanize to a light blue, rinse, dry, and buff again, and it is ready for the coating box.

Silver Solution. Dissolve in 1 quart of soft water, half a pound of Cyanide of Potash. In this dissolve the Chloride of Silver procurable from a silver dollar. Filter, through paper, or clean sponge, and it is ready for use, excepting that it will probably have to be reduced with water. It should be reduced till it works mellow, and free from streaks. The occasional addition of a lump of cyanide will prevent a flowery deposite of oxyde of silver. Occasionally, also, add a little chloride of silver, and more cyanide. The cyanide should always be in excess. The reason why this should be occasionally added, is that the solution becomes too strong, with the silver, from the annode. The connections must be kept bright, with a file or otherwise.

The manner of charging the above battery is as follows: Nearly fill the porous cup with water, and stir in about a tea-spoonful of sulphuric acid. Two or three drops of acid added once a week is enough. The copper cup should be filled with a saturated solution of sulphate of copper, (blue vitriol,) and the solution kept saturated by suspending in it a little sack of the blue vitriol.

The zinc cylinder, previous to use, should be amalgamated, as follows: Place it in a plate, and brighten it by rubbing it with a swab, wet with dilute sulphuric acid. Then with the same swab, rub on mercury, until the whole surface is bright.

Chloride of Silver. Dissolve a silver dollar in about a gill of a mixture of nitric acid and water, equal parts, by the aid of a gentle heat. Let it cool. Throw it into an earthen or glass vessel, containing about 1 quart of strong salt water. Let the precipitate settle. Pour away the liquid, add a large quantity of water, let the chloride of silver settle, pour away the water, and repeat this at least fifty times. The residue is pure chloride of silver.

Any glass or earthen cup, of suitable shape and dimensions, will answer for a solution dish.

It should be remembered that a strong battery, and a strong solution require the plate to be kept at a greater distance from the annode. This distance will range from one to three inches.—Hill's Treatise.