reducing phosphate of copper with charcoal, or charcoal and carbonate of soda. (3) By heating a mixture of 4 parts bone-ash, 1 part charcoal, and 2 parts granulated copper at a moderate temperature. The melted phosphide of copper separates on the bottom of the crucible, and is stated to contain 14 per cent of phosphorus. (4) By adding phosphorus to copper-sulphate solution and boiling. The precipitate is dried, melted, and cast into ingots. When of good quality and in proper condition it is quite black. (5) Copperphosphide is easily prepared by adding to a crucible 14 parts sand, 18 parts bone-ash, 4 parts powdered coal, 4 parts sodium carbonate, and 4 parts powdered glass; the whole being intimately mixed with 9 parts granulated copper. A lid is then luted on and the crucible exposed to a strong heat. The sand acts on the bone-ash, forming silicate of lime. The liberated phosphoric acid is reduced by the coal, and the phosphorus thus set free unites with the copper. (6) Montefiori-Levi and Künzel prepare phosphor-copper by putting sticks of phosphorus into crucibles containing molten copper. To avoid a too ready combustion the sticks of phosphorus are previously coated with a firm layer of copper, by placing them in a solution of copper sulphate. (7) By strongly heating in a crucible an intimate mixture of boneash, copper oxide, and charcoal, phosphor-copper is produced.

65. Phosphor-tin.-(1) When finely divided tin is. heated in the vapour of phosphorus, a silvery-white, very brittle phosphide is obtained, containing about 21 per cent of phosphorus. (2) When phosphorus is dropped into molten tin combination takes place with the formation of a white phosphide, containing about 15 per cent of phosphorus. (3) By placing a bar of zinc in an aqueous solution of chloride of tin, a spongy mass of metallic tin is obtained; by placing this moist tin on the top of sticks of phosphorus in a crucible, pressing down tightly, and then exposing to a gentle heat until the flames of burning phosphorus cease, a crystalline mass of phosphor-tin is obtained.

M

The following excellent plan is adopted for the manufacture of phosphor-copper a

In a cast-iron cruc

is placed the requ phosphorus, then

d

B is tightly joined of screw clamps d

metal is poured in

of manufacture, mechanical treatment, and rate heating. 1 Riche has examined a series of co with regard to fusibility, liquation, and chan resulting from certain operations. The allo chemical formulæ SnCu, and SnCu are the o melt and solidify without decomposition, and points lie between 600° and 700° C.; all othe and copper undergo liquation at the moment of

The several alloys, in quantities of 500 to were fused for ten hours in tubular moulds, an bottom portions of the castings were analys portion of each of the melted alloys was s solidification, and the portion which last rema poured off and likewise analysed. The followi the results:

1 Ann. Chim. Phys. (4) vol. xxx. p. 351

The specific gravity of these alloys is best determined by filing off portions from the upper and lower ends of the casting, and taking the mean of the two densities. In alloys rich in tin expansion takes place (that is to say, the specific gravity of the alloy is less than the mean specific gravities of the two metals) up to the proportion CuSn2; alloys richer in copper exhibit contraction, which is small in the alloy SnCu,, then suddenly becomes very great, attains its maximum in Snču, and then gradually diminishes, the greatest density,

8.91, is found in the alloy SnCug, even ferous alloys exhibiting lower densities, e.g.

The hardness of the alloys, reckoning increases with the proportion of copper down and all the more cupriferous alloys down to tremely brittle, and from this alloy the hard as the proportion of copper increases. The alloy consisting of 66 66 parts tin and 33.3 is said to be the same as that of pure copper.

The alloy SnCu, is distinguished from a several characters; it presents the same hon position after repeated fusion, is peculiar in highest density, exhibits the greatest degree and is so brittle that it may be pounded in a

Bronzes containing from 18 to 22 per cent are used for making wind-instruments, have tl creased by heating and suddenly plunging into on again raising them to a red heat and all cool slowly the density is lowered, but not to t before the sudden cooling. By mechanical t as simple compression or the blow of a coiningby sudden or slow cooling, the density of thes creased, more also (from 8.775 to 8.952) by sudden cooling than by pressure and slow coolin to 8.854). These bronzes, therefore, are affect cooling and by annealing in the opposite ma They cannot be worked at ordinary temperat they break too easily; they are likewise brittle and between 100° and 200° C. But at temper

be forged like

below dull redness they may hammered out into thin plates, and reduced from inch thickness by rolling. This property render able for the fabrication of gongs, which in extern and sonorous qualities, as well as in chemical are identical with the famous Chinese instrume same treatment in the warm state these bronz over, rendered denser, and more easily brought density, than by similar treatment when cold.

Alloys containing 94 to 88 per cent copper and 6 to 12 per cent tin can be rolled and hammered at ordinary temperatures, and are not increased in density by slow or sudden cooling; if they are at the same time subjected to mechanical treatment their specific gravities are slightly increased. A bronze containing 6 per cent tin had its density increased from 8.924 to 8.932, by 72 blows alternating with 24 annealings; and by similar treatment, substituting quick for slow cooling, the density was increased from 8.928 to 8.935.

and

According to the amount of tin present in bronze the colour varies between red and white, and with a large excess of tin it becomes steel-gray. Generally speaking, tin whitens copper more than zinc, 73 parts copper and 27 parts tin forming a white alloy. Alloys containing 89 per cent of copper and upwards are red or reddish-yellow, 88 per cent copper 12 per cent tin is orange-yellow, and the alloy containing 85 per cent of copper is pure yellow; from 85 to 74 per cent copper the yellow colour becomes fainter, and disappears with 72 per cent of copper. Alloys with 1 to 2 per cent of tin are malleable, ductile, and tough, but less so than pure copper. With a greater content of tin the metal becomes less malleable, an alloy with 5 per cent tin can only be worked hot, cracking when hammered cold. Alloys with 15 per cent tin cannot be forged hot or cold. The greatest strength, as previously remarked, being found in bronze used as gun-metal containing about 90 per cent copper and 10 per cent tin. From practical experience it has been found that the greatest strength is obtained by so working as to produce the crystals of the alloy as small as possible, even the kind of mould in which the casting is effected exerting an influence upon the grain, and through this upon the strength. Articles must be cast at a higher temperature in iron moulds than in sand moulds, 1600° C. being required in the former, while 1400° C. will suffice for the latter, especially for large castings.

§ 67. The following table of copper-tin alloys was prepared for the United States Board by the Committee on Alloys (Report, vol. i. 1879, p. 390).