1892.] 



On certa Tinernary A Hoys. 



381 



lead to the following approximations respectively to the composition 

 of the mixtures of metals at the limiting point : 



565750 



Lead 21-23; say 22 



Tin 3436 35 



Zinc 42-44 43 



100 



750850 

 23-25; say 24 

 31-33 32 

 43-45 44 



100 



The critical curve for the higher temperature consequently lies inside 

 that for the lower temperature, since it contains a limiting point 

 corresponding with a smaller tin percentage. 



In order to define the upper portion of the critical curve still more 

 exactly, and thus to deduce a closer approximation to the true 

 limiting point, a number of additional experiments were made at a 

 temperature close to 650, with mixtures containing 31 to 34 per cent, 

 of tin, and lead and zinc in proportions lying between 1 : 1*75 and 

 1 : 2, this being the ratio calculated to yield approximately equal 

 quantities of heavier and lighter alloys, and thus to minimise the 

 error due to imperfect intermixture. The following table gives the 



average values finally deduced from these experiments, together with 

 the majority of the valuations derived from Series I, II, III, IV, and 

 V (Part I), a few experiments in these series being discarded, together 



VOL. L. 



2 D 



