134 Dr. C. R. Alder Wright. [Fck i:. 



applies to the corresponding alloys where aluminium is used instead 

 of zinc, with only this difference, that when the proportion of anti- 

 mony present exceeds a certain amount the mixtures employed no 

 longer remain completely fluid when kept for several hours at 

 temperatures near 850 900 C. ; more or less of the difficultly fusible 

 antimonide of aluminium, SbAl, described in Part VII,* separates 

 out in the solid state ; so that in certain cases where the proportion 

 of antimony is large enough to form a " real " alloy a separation of 

 the constituents still occurs in consequence of this action, the com- 

 pound tending to float up through being lighter than the remaining 

 fluid portion containing the whole of the lead. In consequence, the 

 critical carve indicated by plotting as usual the compositions of the 

 lowermost and topmost portions of the compound ingot ultimately 

 obtained exhibits a sort of excrescence or horn in the central portion, 

 where this abnormal separation occurs. A similar separation by. 

 solidification of aluminium antimonide is also observed in the case of 

 alloys containing (in suitable proportions) aluminium, antimony, and 

 some third metal miscible in all proportions with either of them 

 separately ; thus with zinc as the third metal, under proper condi- 

 tions, solid aluminium antimonide separates, the fluid mother liquor, 

 so to speak, consisting of the zinc, together with whatever aluminium 

 or antimony may be present in excess, and such an amount of AlSb 

 as this fused mixture of metals may be capable of permanently dis- 

 solving at the particular temperature of the experiment. 



Mixtures of Aluminium, Lead, and Antimony. 



The following average values were obtained on examination of 

 twenty compound ingots (forty alloys), prepared by fusing together 

 the weighed metals at a temperature above the melting point of 

 silver, and well stirring, pouring into a nearly white-hot clay test- 

 tube, and keeping this for six to eight hours in a lead bath at the highest 

 temperature practicable with the appliances used. This temperature 

 varied between about 850 and 920, averaging near 880 ; even at the 

 hottest, fragments of pure silver did not run down to a liquid, 

 although they fritted together (melting point of silver near 950 

 The analysis was made in the same way as that of the zinc-1 

 antimony alloys described in Part VII, excepting that the 

 filtrate from the precipitated sulphides of lead and antimony wi 

 directly neutralised with ammonia, the precipitated alumina being 

 weighed , and corrections made for small quantities of F a O s and Si 

 present. 



* The existence of this definite compound, described by the author in the ' Ji 

 Soc. Chem. Industry,' 1892, p. 492, has been since confirmed by D. A. Roche 

 (' Moniteur Scientifique,' 1893, p. 269), who appears to have been unacquainted 

 the previous work on the subject. 





