COPPER, with the exception of titanium, is the only metal which has a red colour: it has much lustre, is very malleable and ductile, and exhales a peculiar smell when warmed or rubbed. It melts at a bright-red or dull-white heat; or, according to Daniell, at a temperature intermediate between the fusing points of silver and gold z=1996° Fahr. Its specific gravity varies from 8.86 to 8.89; the former being the least density of cast copper, the latter the greatest of rolled or hammered copper (Brande, 812).

Copper is used alone for many important purposes, and very extensively for the following; namely, sheathing and bolts for ships, brewing, distilling, and culinary vessels. Some of the fire-boxes for locomotive engines, boilers for marine engines, rollers for calico-printing and paper-making, plates for the use of engravers, etc.

Copper is used in alloying gold and silver, for coin, plate, etc, and it enters with zinc and nickel into the composition of German silver. See p. 279. Copper alloyed with one-tenth of its weight of arsenic is so similar in appearance to silver, as to have been substituted for it.

The alloys of copper, which are very numerous and important, are principally included under the general name, Bran. In the more common acceptation, brass means the yellow alloy of copper, with about half its weight of zinc; this is often called by engineers " yellow brass."

Copper alloyed with about one-ninth its weight of tin, it the metal of braes ordnance, which in very generally called gun-metal; similar alloys used for the "brases " or bearings of machinery, are called by engineers, hard brass, and also gun-metal; and such alloys when employed for statues and medals are called bronze. The further addition of tin leads to bell metal, and speculum metal, which are named after their respective uses; and when the proportion of copper is exceedingly small, the alloy constitutes one kind of pewter. See page 284.

Copper, when alloyed with nearly half its weight of lead, forms an inferior alloy, resembling gun-metal in colour, but very much softer and cheaper, lead being only about one-fourth the value of tin, and used in much burger proportion. This inferor alloy is called pot-metal, and also cock-metal, because it is used for large vessels and measures, for the Urge taps or cocks for brewers, dyers, and distillers, and those of smaller kinds for household use.

Generally, the copper is only alloyed with one of the metals, zinc, tin, or lead; occasionally with two, and sometimes with the three in various proportions. In many cases, the new metals are carefully weighed according to the qualities desired in the alloy, but random mixtures more frequently occur, from the ordinary practice of filling the crucible in great part with various pieces of old metal, of unknown proportions, and adding a certain quantity of new metal to bring it up to the colour and hardness required. This is not done solely from motives of economy, but also from an impression which appears to be very generally entertained, that such mixtures are more homogeneous than those composed entirely of new metals, fused together for the first time.

The remarks I have to offer on these copper alloys will be arranged in the tabular form, in four groups; and to make them as practical as possible, they will be stated in the terms commonly used in the brass-foundry. Thus, when the founder is asked the usual proportions of yellow brass, he will say, 6 to 8 oz. of zinc (to every pound of copper being implied). In speaking of gun-metal, he would not say, it had one-ninth, or 11 per cent, of tin, but simply that it was 1 1/4, 2, or 2 1/4 oz. (of tin,) as the case might be; so that the quantity and kind of the alloy, or the addition to the pound of copper, is usually alone named; and to associate the various ways of stating thens proportions, many are transcribed in the forms in which they are elsewhere designated. See remarks on mixing these alloys, pp. 311 - 316.

Alloys of Copper and Zinc only.

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

1/4 to 1/2 oz. Castings are seldom made of pure copper, as under ordinary circumstances it does not cast soundly: about half an ounce of zinc is usually added, frequently in the shape of 4 oz. of brass to every pound of copper; and by others 4 oz. of brass are added to every two or three pounds of copper.

1 to 1 1/4 oz. Gilding metal, for common jewellery: it is made by mixing 4 parts of copper with one of calamine brass; or sometimes 1 lb. of copper with 6 oz. of brass. The sheet gilding-metal will be found to match pretty well in colour with the cast gun-metal, which latter does not admit of being rolled; they may be therefore used together when required.

3 oz. Red sheet brass, made at Hegermiihl, or 5 1/2 parts copper, 1 zinc, (Ure.)

3 to 4 oz. Bath metal, pinchbeck, Mannheim gold, similor, and alloys bearing various names, and resembling inferior jeweller's gold greatly alloyed with copper, are of about this proportion: some of them contain a little tin; now however, they are scarcely used.

6 oz. Brass, that bears soldering well

6 oz. Bristol brass is said to be of this proportion.

8 oz. Ordinary brass, the general proportion; less fit for soldering than 6 oz. it being more fusible.

8 oz. Emerson's patent brass (1781, see specification, foot-note, p. 312,) was of this proportion; and so is generally the ingot brass, made by simple fusion of the two metals.

9 oz. This proportion is the one extreme of Muntz's patent sheathing. See 10 2/3.

10 2/3 oz. Muntz's metal, or 40 zinc and 60 copper. "Any proportions," says the patentee, "between the extremes, 50 zinc and 50 copper, and 37 zinc, 63 copper, will roll and work at the red heat;" but the first-named proportion, or 40 zinc to 60 copper is preferred.

The metal is cast into ingots, heated to a red-heat, and rolled and worked at that heat into ship's bolts and other fastenings and sheathing.