GILDING.

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Shell-gold, or gold-powder

For painting, may be obtained by uniting one part of goldwith eight of mercury, and afterwards evaporating the latter byheat, which leaves the gold in the form of powder; or otherwisethe metal may be reduced to powder by mechanical trituration,as mentioned already under the article shell-silver.

Cold gilding ly friction.

Steep a fine linen rag in a saturated solution of gold, till it hasentirely imbibed the fluid ; this rag must then be dried over afire, and afterwards burnt to tinder. When any thing is to begilt, it must be previously well burnished; a piece of cork isthen to be dipped, first into a solution of salt in water, and af-terwards into the black powder; and the piece, after being rub-bed with it, must be burnished. This powder is frequently usedfor gilding delicate articles of silver.

I.

Gilding of brass or copper.

Fine instruments of brass, in order that their surface maybe kept longer clean, may be gilt by immersing them severaltimes in a solution of muriate of gold, free from excess of acid,and afterwards burnishing them.

Water-gilding.

This term was probably at first confined to such processes asdemand the use of a solution of gold in nitro-muriatic acid, andmeans a chemical application of gold to the surfaces of metals.If a solution of gold be copiously diluted with ardent spirit, apiece of clean iron will be gilt by being repeatedly steepedtherein.