

1892.] On certain Ternary Alloys. 21 



Mixtures of Aluminium, Lead, and Silver. 



I 



The foregoing experiments -show that no material alteration is 

 produced in the general characters of the critical curves for alloys 

 containing lead (or bismuth) and zinc as immiscible metals and bin 

 as solvent metal, when aluminium is substituted for zinc, excepting 

 that the curves are raised through the diminished solubility of the 

 two immiscible metals jointly in the solvent. The following experi- 

 ments show that a similar result follows when silver is substituted 

 for tin as solvent ; with the difference that, whereas bulges exist in 

 the lower parts of the critical curves when silver and zinc are simul- 

 taneously present, owing to the formation of the definite compounds 

 AgZn 5 and Ag 4 Zn 5 (Part V.), no such bulges are noticeable when silver 

 and aluminium are employed ; suggesting either that corresponding 

 compounds of silver and aluminium are not formed at all ; or that, if 

 they are formed, they are more readily dissociated and broken up on 

 standing molten for seven or eight hours than is the case with the 

 silver-zinc compounds. 



A series of mixtures of aluminium, silver, and lead was prepared, 

 precisely as above described (the same aluminium being used), the only 

 difference being that, on account of the higher fusing point of some of 

 the alloys formed, the crucible in which the first fusion and inter- 

 mixture took place was heated by a small Fletcher's blast gas furnace, 

 instead of a large Bunsen gas burner, provided with a clay jacket and 

 iron chimney, the heat from which, though sufficient for all the mix- 

 tures previously described, was not always high enough to permit of 

 the less fusible highly argentiferous alloys being poured into the 

 clay test tubes cleanly, and without partly solidifying in the crucible 

 during the transference. The temperature of the lead bath was 

 similarly increased by using differently arranged burners in such 

 fashion as to maintain a perceptibly higher temperature than any 

 hitherto used, ranging between 830 and upwards of 900, and averag- 

 ing about 870 or somewhat higher. 



For the lower ties (smaller silver percentages) the lead and alumin- 

 ium were used in the proportions 2 to 1, so that the volumes of the 

 heavier and lighter alloys formed should not differ widely ; for the 

 upper ones increasing proportions of lead were found to be requisite 

 to bring about the same result, so that for the highest ties obtained 

 the lead arid aluminium were originally used in the proportion 10 to 1. 

 Owing to oxidation of lead, however, the ratio of the quantities of 

 the two metals present in the compound ingots finally obtained was 

 perceptibly less than this, by an amount too variable to allow an 

 average to be even approximately estimated. 



The analysis was made by dissolving in nitric acid and precipitating 

 silver as chloride ; the filtrate was evaporated with excess of sulph- 



