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solid-drawn copper tubes, rollers, etc.; an have been added to the copper in melting overcoming the inherent defects.

It must be borne in mind that pure cop mercial article, and although copper is now the large scale in a purer state than prev retains ingredients which modify the valual metal possesses in its chemically pure stat impurities are iron, arsenic, antimony, and so These elements even in very small qua affect copper, but they may be neutralised by uniting them with oxygen. When melted in contact with air, some of the co forming cuprous oxide Cu2O, which makes brittle and unworkable; some air or carbor retained in the gaseous state, and on the 1 at the surface some of this gas will be interior of the mass, and produce a hone ture. To prevent access of air, the metals with charcoal, and this when used judic effective, but the great difficulty is to k carbon has done its work. Carbon in conta produce carbonic oxide, and this gas probably copper to some extent and removes the oxy further excess of carbonic oxide is admitted. the oxides present as impurities, as well as o and the elements being liberated, will alloy w making it brittle and analogous in propert technically known as "overpoled" copper. that commercial copper is impure, but that may be neutralised to a great extent by oxyge is to discover the point when this end has without introducing an excess of air. On the may be as efficacious, and much more easy, to cess of oxygen, and subsequently remove it, by body which has a stronger affinity for oxygen has. To this end Mr. Walton, of the Ansonia

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of the United States of America, has patented a proc preparing copper for casting, which, in the words o patentee, is as follows:

“My present invention is for treating copper in cruc so as to exclude the action of the atmosphere, and su the copper to the action of carbon sufficiently to remov oxygen, and render such copper solid when cast, and ind its malleability and ductility. I take eight pounds of either in the form of an oxide or carbonate, and mix it one bushel of ground charcoal, wet it, and make it i stiff paste, portion it out into, say twenty-four parts, it into rough balls, and dry at a moderate heat. copper is placed in a crucible in a furnace, and when o point of melting, one of the balls is dropped upor copper, and gradually falls in pieces and covers the c as it melts down, thereby entirely excluding the atmos from the surface of the copper; at the same time the in the mass is evolved, and dispels any oxygen which remain in the crucible. It may be supposed that the of zinc will impregnate the copper, but such is not the the charcoal coming in contact with the copper, and of zinc being volatile under the action of heat,1 no com tion with the copper takes place, and the zinc is volat and carried off through the flue, while the charcoal re on the surface of the copper, and combines with any of oxygen and burns. Copper treated in this way become fectly malleable, and is thoroughly toughened, and is, in improved by this treatment. My improvement is espe available when the copper is melted in a crucible, but i be used when melted on a hearth or otherwise. Th purities of common copper are thrown to the surface slag, and the copper made so that it will work better hot or cold, and stand a greater test for either tensi ductility.

"The above method of treatment can be applied to c that is to be used in the manufacture of any article. O 1 Zinc oxide is practically non-volatile. See Percy's Metallurgy,

so treated will remain in a very liquid s than that treated in the ordinary manner can be brought to a very great heat w toughness. When casting such articles as thin castings, a little phosphorus, added jus assists very materially in keeping the metal and also prevents the absorption of oxygen sphere while cooling in the moulds."

§ 22. In addition to the statements al cerning impurities in copper, the following effects of different elements will doubtless b interested in the manufacture of its alloys.

Phosphorus. A small quantity does no the colour of copper, but a large quantity One half per cent makes it very hot-short, a of being rolled in the cold, without cracking. phorus added to molten copper in a cru soundness in the subsequent casting. Phosp the fusibility and hardness of copper, and w quantity, renders it brittle at the ordinar Copper containing 11 per cent of phosphor hard, of a steel-gray colour, is susceptible of but readily tarnishes. In making phosphori adding phosphorus direct, the metal should with an iron rod, as phosphorised iron will a and alloy with the copper.

Silicon. Copper is contaminated with strongly heated in contact with sand and ca containing 2 per cent of silicon resembles colour; is tough, harder than copper, red-shor rolled in the cold. Mr. Anderson of Woolwich containing 1.82 per cent of silicon tougher th If the temperature employed in heating the low, or not sufficiently prolonged, only a little reduced, and the metal will resemble slightly copper.

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Arsenic. Copper and arsenic readily combine w metallic arsenic is dropped into molten copper. Whe very small quantity is thus added, the metal may be into a sound ingot, which contracts during solidification phosphorised copper, and may be rolled cold, and afterw drawn into fine wire. Much arsenic is highly injuri making the metal hard and brittle. Arsenic also rea combines with copper when one of its compounds is he with charcoal in contact with copper.

Iron. The malleability of copper is seriously impa by the presence of iron, which renders the copper har paler in colour, more infusible, and brittle. It may, howe be removed by the use of an oxidising flux.

Lead. One half per cent of lead in copper makes it hot- and cold-short, and can only be removed by cau some of the copper to pass into the slag. In quantities less t this, lead is sometimes added to copper intended for rolli Antimony renders copper hard and brittle, and imp to the fractured surface a dull yellowish-gray colour. more injurious than arsenic.

Bismuth. This metal is stated to exert a speci injurious influence on copper, a very small quantity make hot-short, and makes it sensibly cold-short.

200

Zinc in very small quantity does not much alter character of copper; it tends to impart a yellow colour fibrous fracture. 1000 of zinc in copper makes the la hot-short but not cold-short.

Nickel and Cobalt occasionally occur in copper ores, are reduced along with the copper. These metals m copper less malleable, especially in the presence of a 1 antimony. The metal is then harder and paler in colour

Tin in very small quantity does not appear to affect working properties of copper except to make it a little har

The foregoing remarks concerning the effect of s quantities of foreign metals on the properties of coppe not apply in the same degree when metals are added to co ́in considerable quantities to form what is generally un

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stood by the term "alloys." For example, zinc in copper will make it hard and red-s cent of zinc alloyed with 80 per cent copper exceedingly malleable alloy. Alloys of cop sidered as those alloys in which copper constituent, and not those in which copp ordinate part. Thus standard silver and contain copper, and these are not termed c silver and gold alloys respectively. The copper are: brass, bronze, and German silve the alloys most extensively used in the vario

BRASS

§ 23. The term brass will be used in this all alloys of which copper and zinc are the ess constituents; but it is generally limited in th to those alloys which are decidedly yellow yellowish tint characteristic of common bra zinc and copper are known in commerce b names, and indeed, great confusion has been the multiplication of empirical names to rep the same substance. This is doubtless owing ance that formerly prevailed, when every jealously guarded as a great secret, and fancif to hide the real composition. Moreover, so been handed down to us from very early ti names corrupted so as to have different a different localities. Dr. Percy mentions "t tombac, prince's metal, similor, and Mannheim by some authors to designate alloys consisting o cent copper and 15 per cent zinc; whereas, accor prince's metal and Mannheim gold are synony composed of 75 per cent copper and 25 p according to another author, similor consists per cent copper and 28 per cent zinc; and M

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