204 Analyfis of the 'Emerald of Peru. 



the exigence and direction of this great river ; but its ter- 

 mination ftill continues unknown. 



[To be concluded in the next Number.'] 



XVI. Analyfis of the Emerald of Peru. By M. Vauque- 

 lin. From the Annales de Chimie, Vol. XXVI. 



SEVERAL celebrated chemifts have already analyfed the 

 emerald ; but, as I am convinced that fcience is promoted 

 and individuals inftrucled by repeating the labours of thoie 

 who have preceded us, I have again mbjected this foffil to a 

 chemical analyfis. Klaproth, one of the mod accurate ana- 

 Ivfefc of modern times, found in the emerald of Peru filiceous 

 earth 66.25, alumine 31.25, oxyde of iron 0.50. It will be 

 feen in the courfe of this iliort memoir, that the refult of my 

 labour differs from that of the Pruffian chemift, not only in 

 the proportion of the conftitaent principles, but in their 

 number, and the nature of fome of them*. 



Exp. I. This ftone, broken into fmall fragments, and ex- 

 pofed to a ftrong heat, loft a part of its beautiful green co- 

 lour, and retained only a light lhade of it. In many places of 

 it there were cracks ; and it loft of its weight 0.02 grains. 



Exp. If. Two hundred parts of this foffil, which anfvvered 

 to 200 grains, fold de marc (eight ounces to the pound), or 

 10.615 grammes, were melted for an hour in a filver cru- 

 cible with 600 parts of cauftic potafh. The matter had then 

 a gieenifh yellow colour. This folution, when evaporated 

 to a quarter of its bulk, was converted into a green jelly, 

 the {hade of which was much weakened by deliccation. 



The refidue was diluted in a large quantity of water ; and 

 it was obferved, that the firft portions of this liquid, poured 



* According to the firft analvfis of the cnerald, the refults of which I 

 p.rcfcnted to the National Inftitme, 1 found in it filiceous earth, alumine, 

 lime, and the oxyde of chrome ; but fince that epech, having difcoveicd a 

 rew earth in the beryl, or aigue marine, I repeated my analyfis, under this 

 pew point of view, and I found alio that particular earth, as will be ken, 

 in the cmirfe of this memoir. 



6 upon. 



