538 Dr. C. R. Alder Wright. [Feb. 2 y 



is the case, the ties here all sloping to the right, with the exception of 

 the lower ties in the case of the mixtures lead-tin-zinc and lead-tin- 

 alnmininm; this exception being presumably due, as previously 

 described, to the influence of the endency towards the formation of 

 a definite compound of lead and tin, Pb 3 Sn. 



Alloys containing Zinc with Lead (or Bismuth) and Antimony as Solvent. 



These experiments were made in the same way as before, the only 

 difference being that the temperatures at which the mixtures were 

 kept in tranquil fusion lay between 600 and 700, averaging near 

 to 650. 



The resulting alloys were analysed by dissolving in diluted aqua 

 regia, precipitating by sulphuretted hydrogen (after copious further 

 dilution), separating antimony from lead (or bismuth) sulphide by 

 repeated treatment with ammonium sulphide, and finally collecting on 

 a weighed filter the mixed sulphur and antimony sulphide thrown 

 down on acidulating the filtrate, and heating a known fraction of 

 the dried precipitate in a current of carbon dioxide so as to expel 

 sulphur and leave antimony sulphide. In the case of lead alloys the 

 lead sulphide left undissolved was dissolved in nitric acid, eva- 

 porated with sulphuric acid, and the lead sulphate finally obtained 

 weighed as such; when the acid filtrate from this contained small 

 quantities of zinc (as occasionally happened, owing to zinc sulphide 

 being carried down along with lead and antimony sulphides) this 

 liquid was added to the first zinc-containing filtrate, and the two 

 jointly precipitated with ammonia and ammonium sulphide, the zinc 

 being ultimately transformed into carbonate, and weighed as ZnO as 

 usual, correction being made for traces of Fe 2 3 when present. In 

 the case of bismuth alloys, the bismuth sulphide left undissolved by 

 ammonium sulphide was dissolved in nitric acid, and precipitated 

 boiling by ammonium carbonate. When zinc was present (carried 

 down as sulphide, as before) this was chiefly found in the ammonium 

 carbonate filtrate ; sometimes, however, traces were carried down with 

 this basic bismuth carbonate ; these were separated by dissolving the 

 weighed impure Bi 2 3 in hydrochloric acid, evaporating to drynecs, 

 diluting the residue largely with water, and filtering off from the 

 precipitated bismuth oxychloride. 



In all cases the analyses were calculated taking the sums of the 

 weights of the three metals found as 100. 



Mixtures of Lead, Zinc, and Antimony. 



The following average values were deduced from fourteen com- 

 pound ingots (twenty-eight alloys), the proportion between lead and 

 zinc throughout being near to equality : 



