356 Scientific Intelligence. 



quartz being duly attended to, appears to be between 6.0 and 6.7. Nitro- 

 muriatic acid dissolves the whole, when reduced to powder, with the excep- 

 tion of from 27 to 32 per cent, of quartz. The following process was adop- 

 ted to ascertain the relative proportions of the substances previously found 

 to be contained in it, viz. arsenic, cobalt, iron, bismuth, nickel, copper, 

 and sulphur, with a trace of manganese. A. From the solution in nitro-mu- 

 riatic acid which remained clear when diluted by twelve times its volume 

 of water, the sulphuric acid was precipitated by nitrate of baryta. The pre- 

 cipitate obtained was washed with hot water, and then digested in muriatic 

 acid, and again washed. B. The muriatic acid used in A for digesting the 

 sulphate of baryta contained a little oxide of-bismuth, and was added to the 

 remaining fluid, freed afterwards from the superfluous baryta by sulphuric 

 acid. C. Liquid hydro-sulphuric acid successively added in small quan- 

 tities, till no more change ensued, precipitated a blackish-brown powder, 

 consisting of sulphurets of copper and bismuth. Nitric acid dissolved the 

 precipitate, with the exception of sulphur, and assumed a green colour. It 

 was evaporated, then a great quantity of water added, and the white resi- 

 due collected, repeating the process as long as a precipitate was obtained. 

 D. Caustic ammonia added to the fluid gave an additional minute quantity 

 of a precipitate, which was likewise oxide of bismuth. The result was ig- 

 nited and weighed. E. From the ammoniacal liquid, copper was precipi- 

 tated by caustic potash. The blue precipitate became brown on the solu- 

 tion being heated long enough to expel all the ammonia. The alcaline 

 fluid, treated with hydro-sulphuric acid, gave, after the lapse of several 

 days, a slight quantity of sulphuret of copper. F. From the remaining 

 liquid sulphuretted hydrogen gas orpiment was precipitated. The li- 

 quid was afterwards heated to the boiling point, and the small quantity 

 of orpiment obtained was added to the former. The orpiment was washed 

 several days with boiling water, till the liquid was left colourless by hydro- 

 sulphuret of ammonia. Caustic ammonia left some sulphur undissolved. 

 G. The liquid was concentrated, and nitric acid was added to convert 

 the protoxide of iron into peroxide. The solution rendered neutral by 

 evaporation was diluted, and while hot precipitated by carbonate of soda 

 with excess of base. The precipitate obtained had a brown colour, near- 

 ly like oxide of iron. It was washed with boiling water, and at last dis- 

 solved in oxalic acid. Effervescence ensued, and a yellow fluid was form- 

 ed, while a pale rose-red powder remained undissolved. The liquid, filter- 

 ed off, and warmed, gave, with caustic ammonia, a precipitate of pure ox- 

 ide of iron. H. A slight portion of cobalt dissolved in the liquid was ob- 

 tained on the addition of hydro-sulphuret of potash. A method, simi- 

 lar to that proposed by Laugier, was employed for the determination of 

 the relative quantities of nickel and cobalt ; on the pale red powder of G 

 caustic ammonia was poured, which then assumed a deep mahogany tint, 

 leaving a slight residue undissolved, which proved to be chiefly manganese. 

 K. A portion of cobalt which it contained, and which was dissolved in the 

 carbonate of ammonia, was added to the ammoniacal liquid of O, and al- 

 lowed to stand undisturbed for a fortnight in a flat open vessel. It as- 

 sumed a paler colour, and deposited greenish-blue granular crystals. This 



