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



same no matter what may be the relative proportions of zinc and lead 

 in the total mass ; and this, in point of fact, we find to be the case. 

 But it does not follow therefrom that with a mass of metal containing 

 x per cent, of tin the same pair of alloys will be obtained, no matter 

 in what relative proportions the zinc and lead may exist in the re- 

 maining 100 x per cent. ; and, in point of fact, we find not only that 

 a different pair results for each variation in the relative proportions of 

 zinc and lead in such a case, but, further, that the curves representing 

 the relative distribution of tin in the two alloys are not the same for 

 all proportions between zinc and lead in the total mass. When zinc 

 predominates the curve rises less rapidly, the maximum difference in 

 tin percentage is attained later, and the point of equal distribution of 

 tin throughout the entire mass lies further from the origin than when 

 the zinc and lead are present in equal proportions in the entire mass ; 

 and vice versa when lead predominates. 



Thus the following values were obtained from a series of sixteen com- 

 pound ingots, prepared in the lead-bath at an average temperature of 

 close to 650, the masses remaining fused for about eight hours in each 

 case, the proportions between zinc and lead in the metals weighed up 

 being uniformly 2 to 1. 



Series IV. Zinc double the Lead present. Temperature near 650. 



A similar series of eight ingots at a higher temperature, close to 750, 

 gave the following results : 



