Analysis of Iron Ores, &c. 15 



to precipitate the phosphoric acid, being mixed with nitrate 

 of mercury recently prepared, a brown yellow precipitate 

 was formed, which assumed a green tinge by drying in the 

 air. This precipitate fused with borax gave it a very fine 

 green colour, which proved it to be a chromate of mercury 

 with excess of oxide. 



The presence both of chrome and phosphoric acid in the 

 scoriee from the refining furnace was thus demonstrated. 

 These matters, as well as those that will be mentioned be- 

 low, existed in the pig iron, and previously in the ore, for 

 nothing was added during the processes of working them, 

 from which these could have been produced. 



After chrome, phosphoric acid, manganese, and a por- 

 tion of the silex and alumine, had been separated, M. Vau- 

 quelin dissolved in muriatic acid the ferruginous part, which 

 had then a yellowish red colour. He observed, that, though 

 the alkali had taken from it a great deal of oxide of manga- 

 nese, a perceptible portion of oxygenized muriatic acid was 

 produced, as the dissolution went on. 



A white powder remained at the bottom of the liquor, 

 which, when washed and dried, weighed 88 cent. (13-6 gr.), 

 or about a fifth of the weight of the scoriae. During the 

 evaporation of the liquor, which was carried to dryness, a 

 portion of the same substance was precipitated, which was 

 freed by means of muriatic acid from a little iron that fell 

 down with it. This contained some traces of chrome, for 

 it communicated to borax a decidedly green colour. It was 

 silex. 



M. Vauquelin precipitated the iron from its solution by 

 ammonia, and added to the fdtered solution oxalate of am- 

 monia, which formed in it a pretty copious precipitate 

 of oxalate of lime. 



The iron, still moist and in an attenuated state, was treat- 

 ed with acetous acid, the mixture evaporated to dryness, and 

 the residuum redissolved in water. In the clear and colour- 

 less liquor was detected by different means the presence of 

 oxide of manganese and of alumine, which had escaped 

 the action of the alkali in the first operation, and of a pretty 



large 



