Analyfii of the Emerald of Peru. 20^' 



two parts, and exhibited all the properties of alumine. The 

 liquor, being expofed to the action of fire, depofited, fome 

 moments after, a white infipid duft, full of grains, which 

 diflblved with an effervefcence in acids. Being collected with 

 care, wafhed, and made red-hot, it weighed twenty-fix parts. 

 This fubftance, fubjected to different tefts, exhibited all the 

 characterifing marks of that earth which I found in the be- 

 ryl ; the properties of which I explained at large in a me- 

 moir inferted in the preceding number of the Annales, and 

 which has obtained the name of Glucine^ 



It appears from the experiments announced in the courfe 

 of this analyfis, that ioo parts of the emerald of Peru eon- 

 fiftof 



It appears then by the refult of this analyfis, that there is at 

 very great difference between the proportion, the number, 

 and the nature of the principles which conltitute the eme- 

 rald, and thofe found by Klaproth ; fince, according to him, 

 it is compofed of only 66.25 of filiceous earthy 31.25 alu- 

 mine, and 0.50 of the oxyde of iron. There are in this ftone 

 then three fubltances not obferved by the above chemift, viz. 

 glucine, the oxyde of chrome, and lime ; while the oxyde of 

 iron, which he announces, does not exift in it. 



It follow* therefore from this refult, that the emerald and 



the beryl are two ftones perfectly fimilar, and compofed of 



the fame principles, the colouring matter excepted ; and 



.mineralogy had already got the ftart of chemiftry by bring- 



7 ing 



