Andlyfis of the Emerald of Pefu. 2C5 



upon the fubftance, made it aflume a bright and very agree- 

 able o-reen colour. The folution of the fait had alfo the fame 

 (hade, but weaker. There remained a white infipid fub- 

 ftance, full of grains, which was infoluble in water, and had 

 all the properties of filiceous earth. It weighed 129 parts, 

 after having been expofed to a red heat. 



Exp. III. To the liquor of the fecond experiment, from 

 which the filiceous earth had been feparated, I added cauftic 

 potafn, more than neceffary for faturation, and then boiled 

 it for fome time. The greater part of the matter precipi- 

 tated was at firft re-diffolved ; but there remained a certain 

 quantity which obftinately refilttd folution. The folution 

 having been filtered, the infoluble matter, which, when waffl- 

 ed and dried, weighed feven parts, was collected on the filter. 



This matter had a light lilac colour, which became green 

 by the heat of the blow-pipe. When melted with borax and 

 the fufible fait of urine, it gave them a fuperb green colour, 

 perfectly like that of the emerald. This property of thus 

 giving a green colour to borax and microcofmic fait, made 

 me abandon the idea I had firft conceived, that this matter 

 might lx: the oxyde of nickel ; fince the oxyde of that metal,, 

 though green, communicates to borax a hyacinth colour. As- 

 this colour had a perfect refemblance to that which I ob- 

 tained from the oxyde of the metal* contained in the red lead 

 of Siberia, I directed my experiments with a view to efta- 

 blifh that refemblance. I therefore took this colouring mat- 

 ter, drawn from the emerald, and boiled it to drynefs with 

 concentrated nitric acid. I then poured upon the refidue 

 eauftic potafli, and obtained a folution of an orange-yellow 

 colour; which when mixed with a folution of the nitrate of 

 lead immediately produced the red had of Siberia, and gave, 

 with the nitrate of mercury, a precipitate of a vermilion red 

 eolour, absolutely in the fame manner as does the acid of the 

 red lead. 



< Vauquelin's account of this new metal, called Chrome, will be given 



number. E»:T, 



Thefe 



