390 Scientific Notices — Mineralogy. [Nov. 



flux by the iron smelters, and until its examination by Brie- 

 thaupt, it had been uniformly mistaken for limestone. 



According to the analysis of Prof. C. G. Gmelin, it is com- 

 posed of 



Silica 53-160 



Alumina 14-034 



Lime 14-397 



Soda 2-611 



Magnesia 5-420 



Oxide of iron 7*138 



Oxide of manganese 0-639 



Volatile matter 0-606 



Loss "7-995 



100-000 



(Schweigger and Meiaecke's Jahrbuch der Chemie und Physik, 

 vii. 76.) 



10. Natrbe Compounds of the Oxides of Uranium and Sulphuric 



Acid. 



These new mineral bodies, alluded to by Berzelius, are thus 

 described by Prof. John, their discoverer. 



(1.) Sulphate of Oxidule of Uranium. — It always occurs crys- 

 tallized, and most commonly in flattened prisms, from one to 

 three lines in length, which are arranged in eccentric druses. 

 Colour, beautiful emerald green, sometimes passing into apple 

 green. Lustre considerable, glassy. Transparent ; sometimes, 

 also, opaque and dull. Brittle, and easily pounded. Soluble in 

 water. The solution is precipitated chesnut brown by the triple 

 prussiate of potash, yellowish green by alkalies, and in brown 

 flocks by infusion of nutgalls. Nitrate of silver and metallic 

 iron occasion no alteration ; and a solution of barytes precipi- 

 tates a white powder, insoluble in nitric acid. When ignited, it 

 undergoes partial decomposition ; for if, after this treatment, it 

 be digested in water, a yellow coloured powder remains undis- 

 solved. It accompanies the following mineral, which had here- 

 tofore been erroneously regarded as an oxide of uranium. 



(2.) Subsulphate of Oxide of Uranium. — It forms a thin, 

 botryoidal, intense sulphur-yellow coloured coating over the 

 surface of the minerals on which it is found. It is friable, and 

 soils the fingers. Digested in water, a portion of it passes into 

 solution. The residue dissolves in nitric acid ; and both solu- 

 tions possess the properties of a solution of sulphate of oxide of 

 uranium. 



Both minerals occur in Elias's mine, at the distance of about a 

 league from Joachimsthal, in Bohemia. 



The examination of these compounds, observes Dr. John, 



