18 Dr. C. K. Alder Wright. [June 2, 



Found. 

 Calculated. 



Tin 52-2 



Aluminium... 47'8 



1CKH) 94 100-0 



An analogous point, more clearly marked, was observed with zinc- 

 lead-tin alloys corresponding with the formula SnZn 4 (Part ;V). 



On applying the graphical methods of Sir G. G. Stokes for deduc- 

 ing the position of the limiting point L from the above data (Part V), 

 the first method gives the values 



A-B = 0-6 

 C + C' = 125-0 



and the second 



A+A' = 39-5 

 B + B' = 35-0 



from which the following percentages are deduced : 



1st Method. 2nd Method. Mean. 



Lead 19-0 19'75 19-4 



Aluminium 18'5 17-5 18'0 



Tin., 62-5 6275 62'6 



100-0 100-00 100-0 



This mean value represents a ratio of lead to aluminium not far 

 from that indicated by the formula PbAl 7 . 



Found. 

 Calculated. f A ^ 



Lead 52*3 19'4 = 51-9 



Aluminium . 477 18'0 = 48'1 



100-0 37-4 100-0 



The corresponding ratio with lead-zinc-tin alloys was nearly that 

 indicated by PbZn 6 . 



Mixtures of Aluminium, Bismuth, and Tin. 



A series of mixtures of aluminium, bismuth, and tin was prepared 

 in just the same way ; the analysis of the ternary alloys formed was 

 carried out in precisely the same fashion, excepting that the bismuth 

 sulphide separated from tin sulphide was weighed ultimately as 

 Bi 3 3 ; the results calculated on the sum of aluminium + bismuth + 

 tin = 100 are given in the table below, derived from the examination 

 of 24 compound ingots, representing 48 alloys. As before, the 



