SILVERING.

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at the bottom a stroke may be drawn for the ground. Havingdone this, scatter a few clean brass filings over the whole.

If on the plate of glass is carefully placed another plate of cop-per or brass, and held in a clear coal fire, till it becomes redhot, the whole will appear to be converted into a golden metallicvegetation. Under a glass magnifier, or microscope, this vege-tation appears in a beautiful manner.

Rationale. ..This phenomenon like the former, is producedby the attraction of the copper or brass, for nitric acid beingstronger than that of the silver : the latter losing its oxigen re-turns to the metallic state.

SILVERING.

There are various methods of giving a covering of silver to thesurfaces of bodies. For instance,

Copper may be silvered over, by rubbing it with the follow-ing powder: Two drachms of acidulous tartarite of potash, thesame quantity of muriate of soda, and half a drachm of sulphateof alumine, mixed with fifteen or twenty grains of silver,precipitated from nitrate of silver by copper. The surface of thecopper becomes white when rubbed with this powder, whichmay afterwards be brushed off, and polished with leather.

The sadlers and harness makers cover their wares with tin forordinary uses, (as stated before, page 105) but a cheap silveringis used for this purpose as follows: Half an ounce of silver thathas been precipitated from nitrate of silver by the addition of cop-per 3 muriate of soda, and muriate of ammonia, of each two ounces,and one drachm of muriate of mercury' are triturated together,and made into a paste with water; with this, copper utensilsof every kind, that have been previously boiled with aciduloustartarite of potash, and sulphate of alumine, are rubbed, afterwhich they are made red hot and then polished. The intentionof this process appears to be little more than to apply the silver