128 Dr. Percy and Mr. R. Smith on the Detection of Gold 



stalline fracture, probably due to the presence of antimony. 

 Cupelled 2000 grs., the residual button, parted with nitric acid, 

 left a very minute trace of gold. 



Exp. V. Specimen of lead from the Austrian collection in 

 the Great Exhibition of 1851, labelled "23, Blciberger Pro- 

 bierbiei." Cupelled 2000 grs., treated the remaining button 

 with nitric acid, and obtained a mimite trace of gold. 



Exp. VI. Specimen from ditto, labelled "25, Przibramer 

 "Wcichblei." 2000 grs. cupelled, and the residual button treated 

 with nitric acid, left a trace of black matter ; but the colour of 

 gold could not be distinctly obtained by burnishing, probably 

 owing to a small amount of silver left imdissolved. 



Exp. VII. Repeated Exp. VI. upon 2000 grs., and obtained 

 a %'ery minute trace of gold. 



Exp. VIII. Specimen from ditto, labelled " 26, Przibramer 

 Hartblei." 3340 grs. scorified to a small bulk and then cu- 

 pelled, left a button weighing •! gr. ; treated with nitric acid, 

 left a minute trace of gold. 



Red Lead. 



Exp. IX. Specimen made from Snail-beach lead, Shrop- 

 shire. Mixed 2 lbs. troy of red lead with excess of finely- 

 powdered charcoal, heated the mixture in a Cornish crucible, and 

 poured out the reduced lead into an ingot mould. Of this lead, 

 cupelled 2000 grs., parted the residual button with nitric acid, 

 and obtained a trace of gold. 



Exp. X. Specimen made from Derbyshire lead. Weighed 

 out 5000 grs. of red lead and 300 grs. of powdered charcoal, 

 heated the mixture in a Cornish crucible, the reduced lead 

 weighed 3840 grs. Of this lead, cupelled 2000 grs., the button 

 obtained weighed about •! of a grain; parted with nitric acid, 

 left a trace of gold. 



Litharge. 



Exp. XI. Sample purchased at Mr. C. Button's, Holbom 

 Bars (in the form of small, thin scales). Mixed 6000 grs. with 

 300 grs. of powdered charcoal, reduced the mixture in a Cornish 

 crucible, lead obtained weighed 5460 grs. Of this lead, cupelled 

 2000 grs., obtained a small button of silver ; parted with nitric 

 acid, left a very minute trace of gold. 



Exp. XII. Sample bought at ]Mr. G. James's, 72 Wardour 

 Street (in powder). 6000 grs. reduced by heating with 300 

 grs. of powdered charcoal, gave of lead 4910 grs. Of the lead 

 thus obtained, cupelled 2000 grs., parted the small residual but- 

 ton of silver with nitric acid, and obtained a very minute trace of 

 gold. 



