26 On certain Ternary Alloys. [June 2, 



silver-containing ternary alloys examined (silver-lead-zinc, silver- 

 bismuth-zinc, and silver-aluminium-lead), i.e., the lighter alloy always 

 contains the most silver. With tin as solvent metal, on the other 

 hand, the upper tie-lines always slope to the right, i.e., the heavier 

 alloy contains the most tin ; with bismuth-zinc-tin and bismuth- 

 aluminium-tin alloys this direction of slope is observed with all the 

 tie-lines ; but with lead-zinc- tin and lead-aluminium-tin the lower ties 

 slope to the left, apparently because of the formation of definite com- 

 pounds SnZn 4 and SnAl 4 on the one hand, and SnPb 3 on the other, 

 the influence of the former of which on the bismuth-containing alloys 

 is not perceptible, on account of the lower situation of the curve. 



On applying Stokes' second system to the above figures, a large- 

 scale plotting leads to the values at the limiting point A + A' = 79, 

 B+B' = 4*5 ; whence the composition 



79 

 Bismuth -g = 39'50 



Aluminium = 2*25 



Silver.. = 58'25 



100-00 



representing a ratio between bismuth and aluminium near to that 

 indicated by the formula Bi 2 Al. 



Found. 

 Calculated. 



Bi 93'9 



Al 6-1 



100-0 4175 100-0 



The corresponding ratio found previously in the case of bismuth- 

 zinc-silver alloys was near that indicated by the formula BiZn 3 

 (Part V) ; whence it would seem that, although the composition of 

 the alloys corresponding with certain points on the analogous curves 

 obtained where aluminium is substituted for zinc exhibit some degree 

 of parallelism (e.g., those corresponding with the ratios SnZn 4 and 

 SnAl 4 ), yet this does not apply to the composition represented by the 

 limiting points ; and, further, the composition at the limiting point 

 corresponds with a ratio between the two immiscible metals which 

 varies in each case with the nature of the solvent metal. Thus in 

 the eight cases hitherto investigated the ratios approximately found 

 are as follows : 



