wou d not say, it had one-ninth, or 11 per cent. of tin, but simply that it was 1, 2, or 2 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 these proportions, many are transcribed in the forms in which they are elsewhere designated. ALLOYS OF COPPER AND ZINC ONLY. The marginal numbers denote the ounces of zinc added to every pound of copper. tooz. 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 oz. Gilding metal, for common jewelry: it is made by mixing 4 parts of copper with 1 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 color with the cast gun-metal, which latter does not admit of being rolled; they may be therefore used together when required. Red sheet brass, made at Hegermühl, or 5 parts copper, 1 zinc. 3 oz. 3 to 4 oz. 6 oz. 6 oz. 8 oz. 8 oz. 9 oz. Bath metal, pinchbeck, Mannheim gold, similor, and alloys bearing various names, and resembling inferior jeweler's gold greatly alloyed with copper, are of about this proportion: some of them contain a little tin; now, however, they are scarcely used. Brass, that bears soldering well. Bristol brass is said to be of this proportion. Ordinary brass, the general proportion; less fit for soldering than 6 oz., it being more fusible. Is generally the ingot brass, made by simple fusion of the two metals. This proportion is the one extreme of Muntz's patent sheathing. See 103. 103 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. 12 oz. The metal is cast into ingots, heated to a red-heat, and rolled and worked at that heat into ships' bolts and other fastenings and sheathing. 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. 16 oz. 16 oz. Pale yellow metal, fit for dipping in acids, is often made in this proportion. Soft spelter-solder, suitable for ordinary brass work, is made of equal parts of copper and zinc. About 14 lbs. of each are melted together and poured into an ingot mould with cross ribs, which indents it into little squares of about 2 lbs. weight; much of the zinc is 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 color; it is afterwards passed through a sieve. Of course the ultimate proportion is less than 16 oz. of zinc. Equal parts is the one extreme of Muntz's patent sheathing. See 103. 16 oz. Mosaic gold, which is dark-colored when first cast, but on dipping assumes a beautiful golden tint. When cooled and broken, all yellowness must cease, and the tinge vary from reddish fawn or salmon color, to a light purple or lilac, and from that to whiteness. The proportions are stated as from 52 to 58 zinc to 50 of copper, or 161 to 17 oz. to the pound. 32 oz. or 2 zinc to 1 copper, a bluish-white, brittle alloy, very brilliant, and so crystalline that it may be pounded cold in a mortar. 128 oz. or two ounces of copper to every pound of zinc; a hard crystalline metal differing but little from zinc, 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 zinc, these alloys cannot be arrived at with very strict regard to proportion. The red color 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 oz. of zinc are added to 16 of copper, the mixture has the brilliant silvery color of speculum metal, but with a bluish tint. These alloys, from about 8 to 16 oz. 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 to 9 oz. to the pound. With additional zinc, it is harder and more crystalline; with less, 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. The marginal numbers denote the ounces of tin added to every pound of copper. Ancient Copper and Tin Alloys. oz. 1 oz. 2 oz. 21 oz. Ancient bronze nails, flexible, or 20 copper, 1 tin. Soft bronze, or.. 9 to 1 Medium bronze, or 8 to 1 Hard bronze, or . 7 to 1 6 to 8 oz. Ancient mirrors. 1 oz. 11 oz. 11 oz. According to Pliny, as quoted by Wilkinson. Ancient weapons and tools, by various analyses, or 8 to 15 per cent. tin; metals from 8 to 12 per cent. tin, with two parts zinc added to each 100, for improving the bronze color. Modern Copper and Tin Alloys. Soft gun metal, that bears drifting, or stretching from a perforation. A little harder alloy, fit for mathematical instruments; or 12 copper and 1 very pure grain tin. Still harder, fit for wheels to be cut with teeth. 1 to 2 oz. Brass ordnance, or 8 to 12 per cent. tin; but the general proportion is one-ninth part of tin. 2 oz. 21 oz. 3 oz. 3 oz. 4 oz. 4 oz. 5 oz. Hard bearings for machinery. Very hard bearings for machinery. By Muschenbroek'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 oz. to the pound of copper. Soft musical bells. Chinese gongs and cymbals, or 20 per cent. tin. Large bells. Largest bells. 71 to 81 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 is by some recommended. 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 to this group, Swedish copper, and grain tin, should be used. 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. The 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. 32 oz. of tin to one pound of copper, makes the alloy called by the pewterers" temper," which is added in small quantities to tin, for some kinds of pewter, called "tin and temper,” in which the copper is much less than 1 per cent. REMARKS ON THE ALLOYS OF COPPER. AND TIN ONLY. 2 oz. 4 oz. These metals seem to mix in all proportions. The addition of tin continually increases the fusibility, although when it is added cold it is apt to make the copper pasty, or even to set in a solid lump in the crucible. The red color of the copper is not greatly impaired in those proportions used by the engineer, namely, up to about 2 ounces to the pound; it becomes grayish white at 6, the limit suitable for bells, and quite white at about 8, the speculum metal; after this, the alloy becomes of a bluish cast. The tin alloy is scarcely malleable at 2 ounces, and soon becomes very hard, brittle, and sonorous; and when it has. ceased to serve for producing sound, it is employed for reflecting light. The tough tenacious character of copper under the tools rapidly gives way; alloys of 1 cut easily, 2 assume about the maximum hardness without being crystalline; after this they yield to the file by crumbling in fragments rather than by ordinary abrasion in shreds, until the tin very greatly predominates, as in the pewters, when the alloys become the more flexible, soft, malleable, and ductile, the less copper they contain. ALLOYS OF COPPER AND LEAD ONLY. The marginal numbers denote the ounces of lead added to every pound of copper. A red-colored and ductile alloy. Less red and ductile; neither of these is so much used as the following, as the object is to employ as much lead as possible 6 oz. 7 oz. 8 oz. Ordinary pot-metal, called dry pot-metal, as this quantity of lead will be taken up without separating on cooling; this is brittle when warmed. This alloy is rather short, or disposed to break. Inferior pot-metal, called wet pot-metal, as the lead partly oozes out in cooling, especially when the new metals are mixed; it is therefore always usual to fill the crucible in part with old metal, and to add new for the remainder. This alloy is very brittle when slightly warmed. More lead can scarcely be used, as it separates on cooling. REMARKS ON THE ALLOYS OF COPPER AND LEAD ONLY. These metals mix in all proportions until the lead amounts to nearly half, after this they separate in cooling. The addition of lead greatly increases the fusibility. The red color of copper is soon deadened by the lead; at about 4 ounces to the pound the work has a bluish leaden hue when first turned, but changes in an hour or so to that of a dull gun-metal character. When the lead does not exceed about 4 oz. the mixture is tolerably malleable, but with more lead it soon becomes very brittle and rotten: the alloy is greatly inferior to gunmetal, and is principally used on account of the cheapness of the mixture, and the facility with which it is turned and filed. ALLOYS OF COPPER, ZINC, TIN, AND LEAD, ETC. This group refers principally to gun-metal alloys, to which more or less zinc is added by many engineers. The quantity of tin in every pound of the alloy, which is expressed by the marginal numbers, principally determines the hardness. M. Keller's statues at Versailles are found, as the mean of four analyses, to consist of: 1 to 2 oz. tin to 1 lb. copper used for bronze medals, or 8 to 15 per cent. tin, with the addition of 2 parts in each 100 of zinc, to improve the color. The modern so-called bronze medals of our Mint are of pure copper, and are afterwards bronzed superficially. 1 oz. tin, zinc to 16 oz. copper. Pumps and works requiring great tenacity. |