22 



Dr. C. R. Alder Wright. 



[June 2, 



uric acid, and the lead determined as PbS0 4 ; the filtrate from this 

 was' supersaturated with ammonia, and the weight of the imp 

 alumina found corrected for silica and ferric oxide as before, the 

 results being finally calculated on the sum of silver + aluminium + 



lead as 100. 



The following table represents the results obtained by the examine 

 tion of 26 compound ingots forming 52 ternary alloys. 



Fig. 3 represents the critical curve plotted from these values ; 

 obviously no marked irregularity of contour is visible, nor any tend- 

 ency towards convergence of tie-lines to a fixed point, suggesting 

 that aluminium and silver do not form definite atomic compounds 

 analogous to Ag 4 Zn 5 and AgZn 5 on the one hand, or to AIS^ on the 

 other. The tie-lines uniformly slope downwards to the left, i.e., the 

 lighter alloy always contains more silver than the heavier one, pre- 

 cisely as in the case of zinc-lead-silver alloys. 



The inner dotted curve marked No. 1 represents the curve obtained, 

 as above described, with tin-aluminium-lead alloys, obviously under- 

 lying that obtained with silver- aluminium-lead alloys, notwithstanding 

 that the temperature in the latter case was somewhat higher, about 

 870 as compared with 800. 



The inner dotted curve, marked No. 2, similarly represents the 

 curve obtained with zinc-silver-lead alloys (Part Y), omitting the 



