1889.] 



On certain Ternary Alloys. 



461 



which have been published in the ' Philosophical Transactions ' 

 (vol. 179). It is illustrated partly by representations of certain of 

 the brains showing the extent of the lesions, partly by photographs of 

 microscopic sections through the spinal cord and medulla oblongata. 



III. " On certain Ternary Alloys. I. Alloys of Lead, Tin, 

 and Zinc." By C. R. ALDER WRIGHT, D.Sc., F.R.S., 

 Lecturer on Chemistry and Physics, and C. THOMPSON, 

 F.C.S., F.I.C., Demonstrator of Chemistry, in St. Mary's 

 Hospital Medical School. Received March 5, 1889. 



It is well known, that quite apart from a tendency to separate more 

 or less completely into different mixtures during solidification, certain 

 mixtures of molten metals show a tendency to separate into two alloys 

 of different densities on standing fused for some time. Lead and zinc 

 and bismuth and zinc have been shown by Matthiessen and von Bose 

 (' Roy. Soc. Proc.,' vol. 11, p. 430) to form two such mixtures. We 

 find that aluminium and zinc or aluminium and bismuth also behave 

 in the same "way. In each case two different alloys are formed, one con- 

 sisting of the heavier metal with a little of the lighter one dissolved 

 therein, the other of the lighter metal containing a small quantity of 

 the heavier one. 



On the other hand, tin will alloy indefinitely in all proportions with 

 any one of the four metals, lead, bismuth, zinc, or aluminium, the 

 mixtures exhibiting no particular tendency to separate into two 

 different alloys on simply remaining at rest in a fused condition, 

 although in certain cases more or less separation is apt to occur during 

 solidification, owing to partial formation of eutectic alloy. On quickly 

 cooling a mass of 60 to 80 grams of mixed metal, fused in a small 

 narrow crucible and kept molten for some hours, an ingot is obtained, 

 the highest and lowest portions of which exhibit sensibly the same 

 composition on analysis ; no more difference being observed than may 

 reasonably be attributed to surface oxidation and volatilisation whilst 

 standing molten, and to incipient formation of eutectic alloy during 

 the act of solidification. Thus the following figures were obtained 

 with two ingots of zinc and tin, and similarly in the other cases : 



