

1892.] On certain Ternary Alloys. 11 



V. " On Certain Ternary Alloys. Part VI. Alloys containing 

 Aluminium, together with Lead (or Bismuth) and Tin (or 

 Silver)." By C. R. ALDER WRIGHT, D.Sc.. F.R.S., Lecturer 

 on Chemistry and Physics in St. Mary's Hospital Medical 

 School. Received May 13, 1892. 



The experiments described in the previous five papers* have shown 

 inter alia that when the critical curves are delineated deduced with 

 lead (or hismuth) as heavier immiscible metal, zinc as lighter ditto, 

 and tin (or silver) as " solvent," the curves where bismuth is sub- 

 stituted for lead lie inside, and those where silver is substituted for 

 tin outside, the original curves ; and, further, that in certain cases the 

 formation of definite atomic compounds between particular pairs of 

 metals leads to marked results as regards the mutual relations of 

 the various pairs of conjugate points. Thus, silver and zinc form 

 the compounds AgZn 5 and Ag 4 Zn 5 , with the result of producing 

 marked bulging (inwards or outwards) of the curves deduced with 

 these two metals associated with either lead or bismuth. Tin and 

 zinc appear to form the compound SnZn 4 , with the result of causing a 

 peculiar convergence of the tie-lines when the proportions of metals 

 mixed together permit of the formation of lighter alloys containing 

 tin and zinc in approximately this ratio. Again, the alloys of lead, 

 zinc, and tin are remarkable in that the lower ties slope in one 

 direction, and the upper ones in the opposite direction ; and the 

 position where the angle of slope of the lower ties is greatest (which 

 is approximately the point where the excess of tin percentage in the 

 lighter alloy over that in the heavier one is a maximum) is situated 

 very near to that corresponding with a ratio of tin to lead in the 

 heavier alloy denoted by the formula SnPb 3 . 



The following experiments were made with mixtures of metals cor- 

 responding with those previously described, excepting that aluminium 

 was substituted for zinc. One general result appears to be that this 

 substitution always causes the curve to lie outside of its former 

 position ; and another, that as aluminium does not appear to unite with 

 silver to form compounds analogous to AgZn 5 and Ag 4 Zn 5 , the peculiar 

 bulges observed with silver-zinc-lead and silver-zinc-bismuth alloys 

 are not visible with silver-aluminium-lead and silver-aluminium- 

 bismuth alloys. 



These experiments were commenced about four years ago, at 

 which time moderately pure aluminium was not in the market in any 

 quantity; at least, a number of samples of metals prepared by 



* Part I, < Roy. Soc. Proc.,' vol. 45, p. 461 : Part II, vol. 48, p. 25 ; Part III, 

 vol. 49, p. 156 ; Part IV, vol. 49, p. 174 ; Part V, vol. 50, p. 372. 



