28 Dr. Alder Wright and Mr. C. Thompson. [May 8, 



found more convenient to surround the clay test-tubes with thin 

 wrought iron coverings made of wider tuhes closed at the end ; by 

 so doing, the chance of spoiling an experiment by the infiltration of 

 lead from the bath through minute cracks in the clay was avoided ; 

 moreover, by simply removing from the iron tubes the inner clay 

 test-tubes by means of tongs, a new set of test-tubes containing fused 

 mixtures could be readily introduced into the lead-bath without 

 extinguishing the heating flames ; whereas, when the clay test- tubes 

 were plunged directly into the molten lead, the layer of fritted 

 litharge that formed on the outer surface of the lead-bath sometimes 

 rendered it difficult to remove the clay tubes without agitation. 



Somewhat smaller ingots than those previously used were mostly 

 prepared, usually weighing 50 60 grams, instead of 80 and upwards ; 

 the compound ingots ultimately formed were generally about 7 or 

 8 centimetres long, and 10 12 millimetres diameter. 



The following solubility values for pure lead in pure zinc, and 

 vice versa (no tin being present), were obtained in a number of 

 different observations. 



Percentage of Zinc in Heavier Alloy. 



At 565750 (Part I). At 750 850. 



1-14 1-23 



1-22 1-27 



1-30 1-28 



1-30 1-34 



1-35 



1-36 



Mean T24 Mean T30 



Percentage of Lead in Lighter Alloy. 



At 565750 (Part I). At 750850. 



1-08 1-40 



1-10 1-57 



1-17 1-64 



1-22 1-67 



Mean T14 Mean T57 



It hence results that the solubility of zinc in lead is greater at a 

 temperature near to an average of 800 than at one near to an 

 average of 650 by an amount only just perceptible, and barely 

 outside the limits of experimental error ; whilst the solubility of lead 

 in zinc is increased nearly in the proportion of 3 to 2 by the same 



