420 



METALS. 



and from this point it increases suddenly, ar- 

 riving at a maximum, when the copper and 

 tin are united in the relation of one to three. 

 The density diminishes from this point, then 

 rises again nearly regularly ; the density of the 

 richest copper alloys is inferior to the mixture 

 SnOus, which only contains 62 per cent, of 

 copper. Besides, this alloy may be distin- 

 guished from all the others by its properties ; 

 it is brittle enough to be pounded in a mortar, 

 and forms crystals of a bluish tint, not resem- 

 bling in the least either copper or tin. M. 

 Riche gives a number of formulae, expressing 

 the composition of the definite compounds 

 which copper forms with tin, and their proper- 

 ties. Referring to liquefaction, he then ob- 

 serves, " In order to separate these alloys, the 

 mass should be moved about when becoming 

 solid, to separate the crystals while forming." 

 The fusibility of these alloys has been deter- 

 mined by the thermo-electric pyrometer. M. 

 Riche has operated comparatively with these 

 alloys, and with metals whose fusing-points 

 have been settled by various experimenters. 

 Numerous determinations show that the solidi- 

 fication of the alloys SnCu 3 and SnCu* takes 

 place at a temperature somewhere between the 

 fusion-point of antimony and the boiling-point 

 of cadmium. 



Alloy of Iron and Zinc. One of the German 

 scientific journals says that Dr. Oudemans, 

 Jr., obtained for analysis a piece of metal 

 which had been formed in an iron vessel 

 wherein zinc had been fused for several weeks 

 continually ; this metal was found deposited at 

 the bottom of the vessel, and became an im- 

 pediment to the melting operations, in conse- 

 quence of the relative infusibility of the alloy. 

 In physical aspect this latter was of very much 

 whiter color, and entirely different crystalline 

 structure, than zinc; the alloy dissolved very 

 readily and briskly in dilute sulphuric or hy- 

 drochloric acid, and was found, on analysis, to 

 contain 4.6 per cent, of iron. Taking for 

 granted that this alloy is a definite compound 

 of the two constituent metals, its formula would 

 be: 



FeZn 30 (Fe=56 ; Zn 82.75). 

 Fusibility and Volatility of Metals. -Dr. A. 

 Yon Riemsdyk, while engaged with experi- 

 ments on the intrinsic composition of various 

 pieces of silver money coined at the Royal 

 Netherlands Mint, at Utrecht, investigated the 

 fusibility and volatility of certain metals. The 

 following is an abstract of his record of results : 

 The^ metals tin, bismuth, cadmium, lead, 

 and ^zinc, as chemically pure as they can be 

 obtained, were molten, in order to prevent 

 their oxidation, in a feeble but constant cur- 

 rent of pure and dry hydrogen gas. The 

 author found that (1) the melting of these 

 metals does not, either mechanically or by 

 evaporation, give rise to any loss at all ; (2) 

 that tin, lead, and "bismuth, when kept in a 

 liquid state, are not volatile at temperatures 

 greatly in excess of their melting-points, and 



that, at a bright-red heat, quantities of 2.3433 

 grms. of Usmutn, and 4.5183 grms. of lead, did 

 not lose, by being kept at that temperature for 

 one hour, more than 1 and 0.5 num., respec- 

 tively, by evaporation, while tin did not ex- 

 hibit any volatility at all ; (3) that cadmium 

 and zinc, though completely fixed, non-volatile, 

 at their melting-point, begin perceptibly to 

 volatilize at a few degrees above that point ; 



(4) that there does not exist any relation at all 

 between the fusibility and volatility of these 

 metals, which may be arranged in the follow- 

 ing manner, beginning from the most fusible 

 and most readily volatile : 



Fusibility. Volatility. 



Tin 228.5 C. Cadmium. 



Bismuth 268.3 " Zinc. 



Cadmium 320.0 " Bismuth. 



Lead 326.0 " Lead. 



Zinc 420.0 " Tin. 



(5) that the so-called Rose's fusible metal, an 

 alloy of tin, lead, and bismuth, the melting- 

 point of which is about 97.5, and certainly 

 not higher, is not perceptibly volatile when 

 heated to a bright-red heat in a current of pure 

 hydrogen gas. Silver, unalloyed, melts at 

 1,040 0., pure gold at 1,240 0., while the 

 author found that chemically pure copper re- 

 quires a temperature of 1,330 0. to become 

 liquid. Neither pure silver, nor pure copper, 

 nor also the alloy of silver and copper contain- 

 ing 945-lOOOths of the former metal (this alloy 

 is the standard alloy of the Netherlands silver 

 coins), loses any thing at all by volatilization, 

 when kept for a considerable time at tempera- 

 tures higher than the melting-points of both 

 these metals, and in a feeble current of pure 

 hydrogen to prevent their oxidation. The 

 author has made some of these experiments on 

 a large scale, having at his disposal several 

 hundred kilos of these metals in pure and 

 alloyed state. 



Bronze Manufacture. The great bronze 

 founderies of France are well described in a 

 paper in the Practical Mechanics' Journal. 

 The following account is given of some of the 

 processes employed in the celebrated estab- 

 lishment of M. Barbedienne, at Paris : 



The bronze for all moderate-sized objects, say up 

 to 250 kilos., is melted in clay crucibles, which are 

 made in the neighborhood of Paris, and hold about 

 30 kilos, each. These are not extremely refractory, 

 but stand three or four meltings. 



There are eight crucible furnaces, in form very 

 much that of the ordinary brass furnace, but differing 

 from usual practice, in England at least, in that they 

 are not wind-furnaces, but are fed with blast, from a 

 small fan (about 20 in. diam.), driven by a strap from 

 the engine of the " marbrerie / " the fuel is- coke, and 

 the advantages seem to be patent of this arrange- 

 ment. The metal is " brought down," i. e., melted, 

 very much faster, the " heats " can be repeated much 

 more rapidly, and the consumption of coke is greatly 

 less than with wind-furnaces. Then, again, when 

 the crucibles are about to be " drawn," the blast is 

 thrown off, and there is much less flare and heat to 

 be endured by the man who lifts them out. The 

 tops of these furnaces are of cast iron, the covers of 

 iron-bound square fire-tiles, and the tops are about 

 22 in. above the floor-level. 



