of Mineral Substances. 39 



Analysis of the granular Chromic-Iron Ore, from Steiermark. 



The specific gravity of this ore, freed from the talcose matrix 

 in which it is embedded, is = 4.500. 



a. 100 grains lost by moderate ignition 2 grains, and acquired 

 a perfect metallic lustre : it was levigated, mixed with a lixivium 

 containing 500 grains of caustic potassa, put into a polished 

 iron crucible, evaporated to dryness, and moderately ignited for 

 an hour ; the mass at first frothed up, but afterwards entered 

 into quiet fusion, and when cold was of a sap-green colour; it 

 was readily soluble in warm water, depositing a reddish-brown 

 precipitate, which was collected upon a filter, washed, dried, 

 and digested in boiling muriatic acid. 23 grains remained in- 

 soluble, which were fused with potassa, and treated as before, 

 by which the insoluble portion was reduced to four grains, and 

 was ultimately rendered entirely soluble by another repetition of 

 fusion and solution. 



b. The muriatic solutions were mixed with caustic ammonia, 

 by which a brown precipitate was formed, weighing, when duly 

 washed, dried, and ignited, 35 grains. It was again dissolved 

 in muriatic acid, when it left two grains of siVtca, so that the 

 weight of the oxide of iron was 33 grains. 



c. The green alcaline liquors were carefully neutralized by 

 nitric acid, during which alumina separated, amounting, after 

 having been dried at a red heat, to 6 grains. 



d. The neutralized liquor, after the separation of the alumina, 

 appeared of a fine orange colour. A cold nitric solution of 

 mercury was added to it, till no further precipitation ensued, 

 and till the supernatant liquid appeared colourless and trans- 

 parent. The precipitate, which was of the colour of fine vermilion, 

 weighed, when edulcorated and dried, 369 grains. The mercury 

 was driven off by moderate ignition in a platinum crucible, and 

 there remained pure oxide of chrome of a dark grass-green 

 colour, weighing 55.5 grains. 100 parts, therefore, of the above 

 ore, consist of 



