1894.] On certain Ternary Alloys. 137 



and antimony present relatively to the lead are abnormally increased 

 through the formation of solid AlSb and its admixture with the fluid 

 lighter alloy. 



As regards the direction of slope of the tie-lines, it is noticeable 

 th;it they all slope downwards to the left, as in the case of zinc-lead- 

 antimony alloys. Obviously, the substitution of aluminium for zinc 

 in these raises the critical curve, as in all other similar cases so far 

 examined. On the other hand, the substitution of antimony for tin 

 depresses the curve (so far as the normal portion is concerned, at any 

 rate), just as in the case of zinc-lead-tin and zinc-bismuth-tin alloys. 



Mixtures of Aluminium, Bismuth, and Antimony. 



A parallel series of experiments with aluminium-bismuth-antimony 

 alloys gave the following results as the averages from the examina- 

 tion of twenty-five compound ingots (fifty alloys). The analysis was 

 made as in the case of zinc-bismuth-antimony alloys (Part VII), except 

 that the acid filtrate from the precipitated sulphides of bismuth and 

 antimony was precipitated with ammonia, the A1 2 3 ultimately 

 weighed being corrected for Fe 2 3 and SiO 2 (p. 138). 



Fig. 3 represents these'values plotted on the triangular system, the 

 dotted line No. 1 representing the corresponding results obtained 

 with aluminium-lead-antimony alloys, and the inner dotted line, 

 No. 2, those obtained with zinc-bismuth-antimony alloys (Part VII). 

 Obviously, the substitution of bismuth for lead depresses the critical 

 curve, as usual ; the uppermost portion shows precisely the same 

 irregularity in the form of a central hornlike excrescence, due to the 

 separation of solid SbAl, as was observed with aluminium-lead- 

 antimony alloys ; whilst the lower portion of the right-hand branch 

 shows the same kind of sharply-marked inward depression as was 

 previously observed with zinc-bismuth-antimony alloys, due to the 

 formation of the definite compound of bismuth and antimony, SbzBis, 

 aluminium (like zinc) being capable of dissolving this compound to a 

 greater extent than mixtures of the two metals where one or the 

 other predominates beyond this proportion. 



Calculated 



for 

 Sb 2 Bi 3 . 



Bismuth 72-2 



Antimony . . 27'8 



100-0 



Found at position of maximum 

 depression (5th tie-line). 



/ ' \ 



25-52 = 73-4 



9-2(5 = 26-6 



34-78 100-0 



It is noticeable that the direction of slope of the tie-lines is the same 

 as that with aluminium-lead-antimony alloys, downwards to the left ; 

 whereas with zinc- lead-antimony and zinc-bismuth-antimony the 



