1892.] 



On certain Ternary Alloys. 



19 



mixtures were kept molten for 7 to 8 hours at a temperature lying 

 between 750 and 850, and averaging near 800 C. ; the earlier ties 

 were obtained with mixtures containing bismuth and aluminium in 

 the ratio by weight of 2 - 5 to 1, and the later ones in the ratio 1*5 to 1, 

 and, finally, 1 to 1, in such fashion as to effect approximate equality 

 in volume of the heavier and lighter alloys formed throughout. 



Fig. 2 represents these values plotted on the triangular system, 

 the outer dotted line being the curve above described for aluminium- 

 lead-tin alloys, obviously lying outside the curve obtained with bismuth 

 instead of lead. The inner dotted line represents the corresponding 

 curve with zinc-bismuth-tin (Part V, fig. 7), illustrating the effect of 

 substituting aluminium for zinc.* With the exception that the one 

 lies outside the other, the aluminium-bismuth-tin and zinc-bismuth- 

 tin curves exhibit a close resemblance, the ties uniformly sloping to 

 the right (i.e., the heavier alloy always containing more tin than the 

 lighter one). No marked bulge inwards or outwards, indicating the 

 formation of an atomic compound, is anywhere perceptible. 



The position of the limiting point with zinc- bismuth- tin alloys at 

 650 was deduced (Part V) as yielding a ratio between bismuth 

 and zinc close to that indicated by the formula BiZn 10 ; that similarly 



* The solubility of bismuth in aluminium (without the presence of a third 

 metal) is but little less than that of bismuth in zinc (2'02 per cent, at 870 as com- 

 pared with 2-32 at 650 and 2-47 at 750) ; but the solubility of aluminium in 

 bismuth is greatly inferior to that of zinc in bismuth (0 - 28 per cent, at 870 as 

 compared with 14-28 per cent, at 650 and 15'18 at 750). 



c 2 



