274 M. Berzelius on Uranium. [AprIb, 



flame yellow colour has been fully developed, we still continue 

 to introduce the gas, it becomes deeper, and we finally obtain 

 the ordinary dark coloured sulphuret. This flame yellow 

 coloured substance appears to be a compound of oxide and 

 sulphuret of uranium, an oxysulphuret : muriatic acid dissolves 

 it, and occasions the disengagement of sulphur and sulphuretted 

 hydrogen gas. 



Native Compounds of Uranium. 



Uranium occurs in the mineral kingdom in very few different 

 states of combination. The only ores of it with which we are 

 acquainted are : 1 . The oxidule, in the form of pitchblende, 

 mechanically intermixed with various metallic sulphurets and 

 arseniurets, and with silica. From some of Klaproth's experi- 

 ments, in which the silica was obtained in the state of jelly, it 

 would appear that this mineral is occasionally a silicate of oxi- 

 dule of uranium ; a circumstance which still requires to be 

 satisfactorily established. 2. The hydrated oxide, forming beau- 

 tiful light yellow coloured masses, of a pulverulent texture, and 

 only weakly cohering. When heated, it gives off water, and 

 assumes a green colour ; a proof that it contains no fixed saline 

 basis. 3. Oxide of uranium, forming a dark yellow, sometimes 

 brownish yellow coloured compact mineral. Ignited, it gives 

 off" water, but as it does not become green coloured, it is 

 obvious that it must contain a fixed basis. I have detected in it 

 lime and oxide of lead, and as I have been unable by means of 

 the blowpipe to recognise in it any trace of phosphoric acid, I 

 have reason to regard it as a mixture of several uranates, which 

 probably vary both in their number and in their relative propor- 

 tions. 4. The minerals styled i/;a»7Yes (uran mica), fromAutun 

 and many other localities, and from Cornwall. 5. Sulphate of 

 oxide of uranium, which occurs very sparingly in Joachirasthal. 

 From an examination, chiefly by means of the blowpipe, to 

 which I had an opportunity of subjecting a small specimen, I 

 find it to be a subsalt composed of sulphuric acid, and the oxides 

 of uranium and copper. The latter oxide is probably an essen- 

 tial ingredient in the mineral, as is the case with the double 

 phosphate from Cornwall. 



I shall now relate the details of a minute investigation which 

 I have made of the uranites from Cornwall and from Autun, 

 which, on account of the similarity of their crystalline form, have 

 been heretofore erroneously considered as constituting the 

 same mineralogical species. The localities of this mineral are 

 numerous, although it is never found except in very inconsider- 

 able quantities; as, for example, in Cornwall, Autun, Johann 

 Georgenstadt, Eibenstock, Zinnwald, Bodemais, &c. Bergmann 

 was the first person who analyzed it. The specimen which he 

 examined happened to be the cupreous variety from Cornwall, 



