S18 



Royal Society : — 



was generally about two hours before the metals became solid : in 

 some cases the crucible was placed in a furnace with a low fire so as 

 to cool much slower, but the separation of the metals did not appear 

 to be more perfect than when cooled in the usual manner. When 

 cold the cell was broken, and the top of the alloy separated from the 

 lower part by a blow of the hammer. 



The weight of each casting was about 300 grms., its height about 

 100 millims., and its diameter about 25 millims. 



Lead-Zinc Alloys. 



The Zinc-end. — About 12 grms. were taken from the middle of 

 the end, avoiding the outside. The greater part of the zinc was dis- 

 solved in dilute hydrochloric acid, the residue dissolved in nitric acid 

 and precipitated by sulphuretted hydrogen ; the washed sulphide 

 oxidized by fuming nitric acid, and the lead weighed as sulphate. 

 Or, instead of precipitating by sulphuretted hydrogen, the mixed 

 nitrates were precipitated by ammonia and carbonate of ammonia, 

 and the lead weighed as oxide. 



The Lead-end. — 8 grms. were dissolved in nitric acid, precipitated 

 by sulphuretted hydrogen, the filtrate evaporated almost to dryness, 

 and again treated with sulphuretted hydrogen ; the zinc then thrown 

 down by carbonate of soda and weighed as oxide. 



Analyses of the Lead-zinc Alloys. 



Lead 50 per cent., and zinc 50 per cent. 



Taken lead-end. 

 Taken zinc-end . 



8-000 grm. 

 12-450 „ 



Found. 



Per-centage. 



0-162 ZnO 

 0-161 PbO 



1-62 Zn 

 1-22 Pb 



Lead 66-6 per cent., and zinc 33-3 per cent. 



Taken lead-end... 8*000 grms. 

 Taken zinc-end... 12*55 ,, 



0-162 ZnO 

 0-162 PbO 



1-62 Zn 

 1-20 Pb 



Lead 4 per cent., and zinc 96 per cent. 



Bottom 



19-850 „ 



0-247 PbO S03 

 0-340 „ 



1-20 Pb 

 M7 „ 



Lead 96 per cent., and zinc 4 per cent. 



Bottom 



8-000 „ 



1-63 ZnO 

 1-79 „ 



1-63 Zn 

 1-79 „ 



Bismuth-Zinc Alloys. 

 The Bismuth-end. — About 3 grms. were dissolved in nitric acid, 

 evaporated with hydrochloric acid to destroy the nitric acid, precipi- 

 tated by sulphuretted hydrogen, evaporated almost to dryness, and 

 again treated with sulphuretted hydrogen ; the zinc was lastly preci- 

 pitated by carbonate of soda and weighed as oxide. The analyses 

 marked ( # ) were made in the following manner : — The alloy was dis- 



