On Car mm. 155 



form ; its fracture is indeterminate, compact, and somewhat 

 brilliant; the edges obtuse; its consistence is tenacious and 

 strong; it strikes fire with difficulty, but it does not scratch 

 glass; it is not susceptible of attraction by the magnet ; but 

 when it has been brought to a red heat in the fire, it loses its 

 hardness and six or seven per cent, of its weight. By this 

 operation it becomes friable, and assumes a bright yellow- 

 colour; it does not fuse alone. 



Cronstedt, in his Mineralogy, places it, in consequence of 

 its specific gravity, among the tungstens. In pure frag- 

 ments its weight" is to that of water, as 4733 and 4933 tr» 

 1000. As Schecle did not find wolfram in it, he called it 

 false tungsten. 



According to an analysis of D'Ellhuyar, the constituent 

 principles of this mineral were given by Bergmann, m the 

 Memoirs of the Academy for the year 1784, p. 121, as fol- 

 lows : 



Silex - 022 



Iron - 024 



Lime - 054 



100 

 Heated by the blow-pipe with borax, it forms a glass glo- 

 bule, which, wlijn warm, appears greenish, but colourless 

 when it has cooled. When fused vvith carbonate of soda, 

 in a platina spoon, it is not dissolved. 



II. An ahj sis of Cerium. 



To separate iheyttria, which it was suspected to contain, 

 it was reduced to a fine powder in a porphyry mortar, and 

 pure concentrated nitric acid was then added to it. The acid 

 was decomposed, and a considerable quantity of nitrous and 

 carbonic acid ga?es was disengaged. The stony powder 

 was several times treated with acid, until the insoluble resi- 

 duum appeared white. 



The solution, diluted with water, had a yellow colour, 

 which became greenish by ebullition, and then red ; — when 

 dried compk tcly, it became yellowish white; but by attract- 

 ing humidity it resumes its red colour. 



In alcohol it is entirely dissolved, and the solution, when 

 slightly digested, deposits a considerable quantity of oxide of 

 iron. It deposited also more oxide of iron during a rest 

 of some days in a window. The solution decanted, being 

 almost clear, was evaporated to dryness, and the salt cal- 

 cined exhibited a powder of a brick colour. Water was 



able 



