1891.J 



On certain Ternary Alloys. 

 Solubility of Bismuth in Zinc- Tin. 



163 



On comparing these mean curves with those described in Parts I 

 and II, obtained with lead-zinc-tin alloys, it is evident that the solu- 

 bility of zinc in bismuth is always greater than that in lead, whether tin 

 be absent or present to a given extent in each case ; and that, in the 

 latter case, the rate of increment in the solubility of zinc in bismuth 

 the proportion of tin present increases is more rapid than the 

 corresponding rate of increment in the solubility of zinc in lead, 

 'recisely similar remarks apply to the solubility of bismuth in zinc. 



Mixtures of Bismuth, Zinc, and Silver. 



It has already been mentioned in Part II that mixtures of bismuth, 

 zinc, and silver show the same remarkable behaviour as analogous 

 mixtures of lead, zinc, and silver, leading to the conclusion that two 

 definite compounds of zinc and silver are formed under appropriate 

 conditions, indicated respectively by the formulae AgZn 5 and Ag 4 Zn 5 ; 

 of which the first is characterised by being capable of dissolving more 

 lead (or bismuth) than can either pure zinc or the second compound, 

 and of being more soluble in lead (or bismuth) than either of these ; 

 also of being somewhat unstable, so that when a solution of lead (or 

 bismuth) in AgZn 5 is kept molten for a long time it breaks up forming 

 zinc and Ag 4 Zn-, which being unable to dissolve all the lead originally 

 present, causes the separation of lead from the liquid metal as a heavier 

 alloy containing a little zinc and silver in solution. The second com- 

 pound Ag 4 Zn 5 is characterised by the peculiar red colour assumed by 

 a recently cut or filed surface exposed to the air for awhile, and by 



