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Foils (It is desired to have)

it is desired to have the appearance more orange or scarlet. has been sometimes used, with which it has been Foils may be made of copper or tin; and silver advised, for some purposes, to mix gold; but the expense of either is needless, as copper may be made to answer the same end. can be supplied at a price 40 per cent. less than | much inclined to the blue, or under crimson, where silver, and its greater hardness will give it a marked superiority. It may also serve as a substitute for gold-plated or silver-plated articles, which are now so common on account of their cheapness, but which will not bear replating more than a few times, and which are, in the long run, sometimes more expensive than the pure metal. The new alloy, however, will be most useful for small coin.

Its preparation and coinage are so difficult that the coin made of it cannot easily be counterfeited.

Its hardness would render it more durable than silver; and thus the expense of re-coining, and the heavy loss arising from the wearing of our silver coinage, would be greatly diminished.

Silver Test.

Silver coins, jewelry, or any other rich alloy, when moistened with a solution of chromic acid, or a mixture of bichromate of potassa and sulphuric acid, become covered with a red purple spot of bichromate of silver. This spot does not occur on poor alloys or metals imitating silver.

Useful Alloy of Gold with Platinum.

Put into a clean crucible 7½ drs. of pure gold, and when perfectly melted, throw in 1 a dr. of when perfectly melted, throw in a dr. of platinum. The 2 metals will combine intimately, forming an alloy rather whiter than pure gold, but remarkably ductile and elastic; it is also less than pure gold or jewellers' gold; but more readily fusible than that metal.

These excellent qualities must render this alloy an object of great interest to workers in metals.

For springs, where steel cannot be used, it will prove exceedingly advantageous.

It is a curious circumstance, that the alloy of gold and platinum is soluble in nitric acid, which does not act on either of the metals in a separate state. It is remarkable, too, that the alloy has very nearly the color of platinum , even when composed of 11 parts of gold to 1 of the former metal.

Ring Gold. مد Melt together of Spanish copper, 6 dwts. and 12 grs.; fine silver, 3 dwts. and 16 grs., to 1 oz. 5 dwts. of gold coin.

Gold from 35s to 40s per oz.

Melt together 8 oz. 8 dwts. of Spanish copper, 10 dwts. of fine silver, to 1 oz. of gold coin.

Manheim-Gold, or Similor.

To Prepare Copper for Foils.

Where colored foils are wanted, copper may therefore be best used, and may be prepared for the purpose, by the following means:

Take copper plates beaten to a proper thickness, and pass them betwixt a pair of fine steel rollers very close set, and draw them as thin as is possivery fine whiting, or rotten-stone, till they shine, ble to retain a proper tenacity. Polish them with and have as much brightness as can be given them, and they will then be fit to receive the color.

To Whiten Foils.

Where the yellow, or rather orange-color of the ground would be injurious to the effect, as in the whitened, which may be done in the following case of purples, or crimson red, the foils should be manner: in aqua-fortis, and then put bits of copper into the Take a small quantity of silver and dissolve it solution, and precipitate the silver; which being done the fluid must be poured off, and fresh water first fluid; after which the silver must be dried, an added to it, to wash away all the remainder of the equal weight of cream of tartar and common salt must then be ground with it, till the whole be reture, the foils, being first slightly moistened, must duced to a very fine powder; and with this mixthis mixbe rubbed by the finger, or a bit of linen rag, till they be of the degree of whiteness desired; after which, if it appear to be wanted, the polish must be refreshed.

The tin foils are only used in the case of colorless stones, where quicksilver is employed; and they may be drawn out by the same rollers, but need not be further polished, as that effect is produced by other means in this case. Foils for Crystals, Pebbles, or Paste, to give the Lustre and Play of Diamonds.

The manner of preparing foils, so as to give colorless stones the greatest degree of play and lustre, is by raising so high a polish or smoothness on Melt together 34 oz. of copper, 1½ oz. of brass, the surface, as to give them the effect of a mirror, and 15 grs. of pure gold.