For the preparation of phosphorus compounds of metals, for example, phosphor-copper, Dr. Schwarz gives the following directions:-A mixture of bone-ash, silica, and carbon is placed in a crucible, and upon it a layer of granulated copper, which is in turn covered with the above mixture. The lid of the crucible is luted on. To make it melt more easily, some carbonate of soda and glass may be added, or a mixture of pulverized milk-glass with charcoal and powdered coke is used for lining and covering it. Take, for example, 14 parts of silica, 18 of bone-ash, and 4 of powdered carbon. This is mixed with 4 parts of soda and 4 of powdered glass, stirred up with a little gum water, and used to line the crucible. When this is dry, the copper is put in and covered with the same mass, and the whole is melted at a bright-red heat. The copper obtained flows well, and has a reddish-grey colour. It contains 0.50 to 0.51 per cent. of phosphorus.

The simplest method for introducing phosphorus into bronze is to stick a bar of the phosphorus into a tube of pinchbeck, one end of which is hammered together and closed tightly. After the phosphorus is put in, the other end is closed too. When the metal, which contains 32 parts of copper to 5 of zinc and 1 of tin, is melted, the tube charged with phosphorus is pushed down in it to the bottom of the crucible by means of bent tongs. The stick of phosphorus must always be kept under water until it is about to go into the pinchbeck tube, when it must be carefully dried, as the presence of any moisture would be sure to cause the metal to spurt or fly about.

Another way of introducing the phosphorus is as follows :-Get about 2 ft. of iron barrel from a gasfitter, the bore a little larger than the sticks of phosphorus; make an iron plug to fit the bore, and then drive it down one end of the pipe until the space will hold the quantity of phosphorus you wish to mix in the bath, minding not to split the barrel in driving in the plug. Make a plug of tin about J in. thick to fit in the bore; now introduce your phosphorus into the space formed by the iron plug, and just tap the tin plug into the end of the barrel with a hammer. Stir it about in the molten metal; the tin plug soon melts, letting out the phosphorus in the bronze bath. Use bronze plugs for the end only.

In 1868, Montefiore and Kunzel, of Liege, Belgium, observed that the tin in bronze progressively decreases by oxidation during smelting, the tin oxide going partly into the slag and being partly dissolved in the molten metal, so that bronze originally composed of 10. 10 per cent. tin and 89.90 copper, after the 4th melting contained only 8.52 tin and 91.48 copper. It was found that " poling" (stirring up the molten metal with a wooden stick) eliminated, the oxide combined with copper, but had no effect on the tin oxide. Kunzel then tried the introduction of a little phosphorus, or phos-phuret of tin or copper, into the mass, with the desired result. Bars cast from the same crucible of metal under the three conditions named gave the following figures:-

Other experiments in phosphorizing alloys of copper, nickel, manganese, and iron, were not satisfactory; nor was that of using sodium instead of phosphorus as a deoxidizer. The action of phosphorus in bronze is (1) to eliminate the oxides, and (2) to make the tin capable of assuming crystalline structure, thus increasing the homogeneity of the alloy, and thereby its elasticity and absolute resistance. Among other properties, phosphor-bronze emits sparks under friction much less readily than gun-metal or copper; it is peculiarly adapted for friction-bearings; is easily rolled into sheets, and is very tough in that form; and oxidizes in sea-water at about one-third the rate of copper.

Platinum is capable of being united to most other metals, the alloys being as a rule more fusible than platinum itself. It occurs in nature in combination with a rare metal called iridium, with which it is often alloyed; the resulting metal is called iridio-platinum, and, though still malleable, is harder than platinum, and unattacked by aqua regia. It is also much less readily fusible than platinum itself, and is therefore likely to be largely used in place of this metal for the purpose of electric lighting by incandescence. Silver is hardened, but rendered brittle, by being alloyed with very small quantities of platinum.