462 Dr. C. R. A. Wright and Mr. C. Thompson. [Mar. 28, 



Various other metals, e.g., cadmium, antimony, silver, &c., appear to 

 hehave like tin in this respect. 



It occurred to us that it would be of interest to examine the 

 behaviour under similar conditions of ternary mixtures where two of 

 the ingredients are not miscible together in all proportions (like 

 aluminium and lead), whilst the third is miscible indefinitely with 

 either of the other two (like tin) . A priori, it would seem probable that 

 such mixtures would behave in a fashion similar to mixtures of 

 alcohol, ether, and water. It is well known that these three fluids can 

 be mixed together in certain proportions so as to form a single homo- 

 geneous liquid, not separating into two different layers on standing ; 

 whilst, on the other hand, certain mixtures of alcohol and ether, when 

 agitated with water, ultimately form two different fluids, the heavier 

 one consisting of water containing in solution some alcohol and ether, 

 the lighter one of ether retaining the rest of the alcohol and some 

 water. By parity of reasoning it might be expected that with certain 

 proportions a single stable alloy would result, whilst with others the 

 mass would divide into two different ternary mixtures. In point of 

 fact this is precisely what occurs. 



For a variety of reasons we selected the alloys of lead, tin, and zinc 

 for our first experiments : these metals are easily obtained in quantity 

 and of fair purity ; the mixtures are fusible at temperatures easily 

 attained and controlled; and the analysis of the resulting alloys is 

 comparatively simple and easily executed with accuracy, no unim- 

 portant point when some 200 to 300 different alloys are to be ex- 

 amined, as we found to be ultimately necessary. Our first preliminary 

 experiments indicated that when the lead and zinc are present in 

 proportions not widely different (between the limits 3 to 1 and 1 to 3), 

 the quantity of tin requisite to prevent separation into two different 

 alloys was from i to f (33 to 40 per cent.) of the total mass, i.e., such 

 mixtures, after standing quiescent in a molten state for several hours 

 and then cooled, gave ingots exhibiting sensibly the same composition 

 at top and bottom. For example, the following figures were obtained 

 with five different mixtures where the tin was always not less than 

 35 per cent, of the whole, whilst the zinc and lead varied in their ratio 

 between the limits 1 to 2 and 2 to 1 or thereabouts : 



