12 oz. Spelter-solder for copper and iron is sometimes made in this proportion; for brass work, the metals are generally mixed in equal parts. See 16 oz.

12 oz. Pale yellow metal, fit for dipping in acids, is often made in this proportion.

16 oz. Soft spelter-solder, suitable for ordinary brass work, is made of equal parts of copper and zinc. About 14 lb. of each are melted together and poured into an ingot mould with cross ribs, which indents it into little squares of about 2 lb. weight; much of the zinc in lost. These lumps are afterwards heated nearly to redness upon a charcoal fire, and are broken up one at a time with great rapidity on an anvil or in an iron pestle and mortar. The heat is a critical point; if too great, the solder is beaten into a cake or coarse lumps, and becomes tarnished; when the heat is proper, it is nicely granulated, and remains of a bright yellow colour; it is afterwards passed through a sieve. Of course the ultimate proportion is less than 16 oz. of zinc.

16 oz. Equal parts is the one extreme of Muntz's patent sheathing. See 10 2/3.

16 1/2 oz. Hamilton and Parker's patent Mosaic gold, which is dark-coloured when first cast, but on dipping assumes a beautiful golden tint When cooled and broken, say the patentees, " all yellowness must cease, and the tinge vary from reddish fawn or salmon colour, to a light purple or lilac, and from that to whiteness." The proportions are stated as from 52 to 58 zinc to 60 of copper, or 16 1/4 to 17 ox to the pound. Repertory, vol. ill p. 248. 32 ox or 2 sine to 1 copper, a bluish-white, brittle alloy, very brilliant, and to crystalline that it may be pounded cold in a pestle and mortar.

128 oz. or 2 ounces of copper to every pound of sine; a hard crystalline metal, differing but little from sine, but more tenacious, it has been used for laps or polishing disks.

Remarks On The Alloys Of Copper And Zinc

These metals seem to mix in all proportions.

The addition of zinc continually increases the fusibility, but from the extremely volatile nature of sine, these alloys cannot be arrived at with very strict regard to proportion. See remarks on those alloys, pages 311 to 316.

The red colour of copper slides into that of yellow brass at about 4 or 5 oz. to the pound, and remains little altered unto about 8 or 10 oz.; after this it becomes whiter, and when 32 ox of zinc are added to 16 of copper, the mixture has the brilliant silvery colour of speculum metal, but with a bluish tint

These alloys, from about 8 to 16 ox to the pound of copper, are extensively used for dipping, as in an enormous variety of furniture work: in all cases the metal is annealed before the application of the scouring or cleaning processes, and of the acids, bronzes and lackers subsequently used.

The alloys with zinc retain their malleability and ductility well, unto about 8 or 10 ounces to the pound; after this the crystalline character slowly begins to prevail. The alloy of 2 zinc and 1 copper, before named, may be crumbled in a mortar when cold.

The ordinary range of good yellow brass, that files and turns well, is from about 4 1/2 to 9 ox to the pound. With additional zinc, it is harder and more crystalline; with lees, more tenacious and it hangs to the file like copper; the range is wide, and small differences are not perceived.

Alloys of Copper and Tin only.

(Note. - The marginal numbers denote the ounces of tin added to every pound of copper.)

Ancient Copper and Tin Alloy*.

Modern Copper and Tin Alloys.

1 oz. Soft gun-metal, that bears drifting, or stretching from a perforation,

1 1/2 oz. A little harder alloy, fit for mathematical instruments; or 12 copper and 1 very pure grain tin.

1 1/2 oz. Still harder, fit for wheels to be cut with teeth.

1 1/2 to 2 oz. Brass ordnance, or 8 to 12 per cent, tin; but the general proportion is one ninth part of tin.

2 oz. Hard bearings for machinery.

2 1/2 oz. Very hard bearings for machinery. By Muschenbroeck s Tables it appears that the proportion 1 tin and 6 copper is the most tenacious alloy; it is too brittle for general use, and contains 2 1/4 oz. to the pound of copper. See p. 289.

For some other alloys used in machinery, see Alloys of Copper, Zinc, Tin, and Lead, page 272.

3 oz. Soft musical bells.

3 1/2 oz. Chinese gongs and cymbals, or 20 per cent tin. (Ure, fol. 191.)

4 oz. House bells.

4 1/2 oz. Large bells.

5 oz. Largest bells.

7 1/4 to 8 1/4 oz. Speculum metal. Sometimes one ounce of brass is added to every pound as the means of introducing a trifling quantity of zinc, at other times small proportions of silver are added; the employment of arsenic was strongly advocated by the Rev. John Edwards. Lord Oxmantown, now the Earl of Rosse, says, " tin and copper, the materials employed by Newton in the first reflecting telescope, are preferable to any other with which I am acquainted; the best proportions being four atoms of copper to one of tin (Turner's numbers); in fact, 126.4 parts of copper to 58.9 of tin." - Trans. Royal Soc. 1840 , p. 504.

The object agreed upon by all experimentalists appears to be the exact saturation of the copper with the tin, and the proportionate quantities differ very materially, (in this and all other alloys,) according to the respective degrees of purity of the metals: for the most perfect alloys of this group, Swedish copper, and grain tin, should be used.

Mr. Ross says, "When the alloy is perfect, it should be white, glassy, and flaky. When the copper is in excess, it imparts a red tint easily detected; when the tin is in excess, the fracture is granulated and also less white." His practice is to pour the melted tin into the fluid copper when it is at the lowest temperature that a mixture by stirring can be effected, then to pour the mixture into an ingot and to complete the combination by remelting in the most gradual manner, by putting the metal into the furnace as soon almost as the fire is lighted: trial is made of a little piece taken from the pot immediately prior to pouring.