1889.] On certain Ternary Alloys. 479 



v. Bose (loc. cit. supra), which lead to the percentages 1*62 1'79 of 

 zinc in heavier alloy, mean = 1'67; and 1*17 1'22 of lead in lighter 

 alloy, mean = T20. Obviously this arises from the fact that the 

 method of working adopted by Matthiessen and v. Bose did not allow 

 of so complete a separation taking place as was effected in our experi- 

 ments, as they employed a far shorter time. 



Variation in mean Composition through Oxidation and Volatilisation. 



In melting and mixing together the metals employed, it is quite 

 impossible to avoid some loss by .oxidation, even when a luminons gas 

 flame is directed into the crucible so as to maintain a reducing 

 atmosphere therein. Moreover, some amount of volatilisation, espe- 

 cially of zinc, takes place, owing to prolonged heating at 650 750. 

 A number of observations made with mixtures that did not separate 

 into two alloys showed that the total quantity of tin in the final ingot 

 is but little, if at all, less than that originally weighed up ; some lead 

 is lost and more zinc, roughly averaging about twice as much as the 

 lead. The total amount of loss, however, even after eight hours' 

 heating, is not very great ; as a rule, ingots were made for which 

 about 80 grams of total metal were weighed up ; the weight of final 

 compound ingot was generally near to 77 grams (excluding mechanical 

 losses during stirring and transference to the clay test-tubes), about 

 3 grams representing the loss by oxidation and volatilisation. In a 

 few cases a larger amount of oxidation took place, but comparatively 

 rarely with careful handling. The result of this action is to cause an 

 increment in the mean percentage of tin in the mass to the extent of 

 something like one twenty-fifth of its value (i.e., a mass originally 

 containing 25 per cent, of tin will ultimately contain about 26). 

 Simultaneously the ratio of zinc to lead is altered ; only to a small 

 extent if these metals were originally in the proportion of 2 to 1, 

 but relatively more if the zinc were present to a lesser extent. 



In the foregoing experiments the proportions subsisting between 

 zinc, lead, and tin referred to are uniformly those in which the metals 

 were weighed up for use, and consequently not quite the same as those 

 actually subsisting in the compound ingots finally obtained; these 

 latter probably contained zinc and lead in ratios near to 2 to 1, 0*96 to 

 1, and 0'46 to 1, respectively, on the average. 



Summary of Results. 



When a mixture of lead, tin, and zinc in the molten condition is 

 well stirred up by mechanical means and then left to itself for some 

 hours at as nearly as possible a uniform temperature, a single homo- 

 geneous alloy results if the proportion of tin present is not less than 

 three-eighths of the whole ; but if materially less tin than this is 



