53 2 Dr. C. R. Alder Wright. [Feb. 2 r 



poured into hot clay test-tubes, and kept 78 hours in the lead bath. 

 To diminish possible volatilisation of cadmium, the temperature 

 employed was somewhat lowered, so that it always lay between 550 

 and 650, averaging near to 600. 



The analysis of the alloys containing lead, zinc, and cadmium was 

 effected by dissolving in nitric acid and evaporating with sulphuric 

 acid ; the nitrate from the lead sulphate was diluted, further acidulated 

 with hydrochloric acid, and treated with sulphuretted hydrogen till all 

 cadmium was precipitated. The cadmium sulphide thus thrown 

 down generally carried down more or less zinc sulphide ; to separate 

 this, the mixed sulphides were dissolved in a little hot concen- 

 trated hydrochloric acid, diluted, and again treated with sulphur- 

 etted hydrogen, the process being repeated when necessary, till no 

 more zinc was contained in the nitrate. The cadmium sulphide 

 finally obtained was dissolved in hydrochloric acid, and bromine 

 water added in excess to destroy sulphuretted hydrogen ; finally, 

 the cadmium was precipitated boiling by sodium carbonate, and 

 ultimately weighed as CdO. The acid liquors containing zinc were 

 united and treated with ammonia and ammonium sulphide, the zinc 

 sulphide being finally converted into carbonate and weighed as ZnO, 

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



The alloys containing bismuth instead of lead were examined in 

 the same way, excepting that the alloy was dissolved in nitro-hydro- 

 chloric acid, and the solution evaporated to dryness and treated 

 with a large bulk of water, so as to separate the bismuth as oxy- 

 chloride. This oxychloride was boiled with ammonium sulphide to 

 remove chlorine (which is apt to interfere with proper conversion 

 into carbonate), and the resulting bismuth sulphide dissolved in 

 nitric acid, the solution being precipitated boiling with ammonia 

 and ammonium carbonate, and the bismuth finally weighed as 

 Bi 2 3 . 



Mixtures of Lead, Zinc, and Cadmium. 



The followirig figures were obtained as the averages from the 

 examination of 24 compound ingots (48 alloys). In the mixtures 

 used for deducing the earlier ties, the lead and zinc were used in 

 about equal quantities; subsequently the proportion of lead was 

 increased relatively to the zinc, until finally the two metals were 

 employed in about the ratio 10 to 1, this being found necessary to 

 bring about the formation of the lighter and heavier alloys in not 

 widely different quantities. The percentages are uniformly reckoned 

 *m the sum of the weights of the three metals found as 100. 





