84 SCIENCE PROGRESS. 



gradually converted at a constant temperature into its con- 

 jugate, with precipitation of A, while the other conjugate, 

 if heat be taken from it, will slowly cool with precipitation 

 of A. 



ON TERNARY ALLOYS. 



Practical metallurgists have long ago recognised that 

 the addition of a third metal to an alloy materially alters 

 its properties, and the number of ternary alloys, or mixtures 

 ot three metals, that have been devised for special uses is 

 very large, many different alloys being used for the same 

 purpose by different manufacturers. A good deal of light 

 has been thrown on this complicated subject by the researches 

 of Alder Wright. 1 Developing facts previously studied by 

 Duclaux 2 in the case of mixtures of water, ether, and 

 alcohol, he has shown that if we take two partially miscible 

 liquids, such as lead and zinc, in such proportions that the 

 mixture separates into two conjugate alloys, then by the 

 addition of a third metal, such as tin, which is freely soluble 

 in both the others, we can increase the solubility of the lead 

 and zinc in each other. The two conjugates can thus be 

 made to approach each other in composition, and a sufficient 

 amount of tin will make them identical, so that for this and 

 all higher proportions of tin, the three metals will form a 

 homogeneous mixture. The third metal thus acts somewhat 

 like a rise in temperature in Alexejew's experiments (fig. i). 



It is not improbable that the beneficial effect of the third 

 metal in many alloys in use, is due to its thus rendering the 

 mixture of the other two homogeneous. Alder YY right's 

 method of experiment was to melt the three metals together 

 in the desired proportion and pour the mixture into a long 

 narrow crucible of clay, which was maintained lor several 

 hours at a constant temperature well above the melting 

 point. The alloy was then rapidly cooled, and the upper 

 and lower parts of the ingot analysed. In those cases 

 where the amount of the third metal was insufficient to 



1 Loc. cit. 



~ Annales de Ch. et Ph. (5), 7, 264, 1876. 



