390 Hillebrand — Occurrence of Nitrogen in Uraninite. 



The correctness of the ortho-uranate formula for Broggerite 

 itself having been invalidated by the difference between his 

 own and analysis XII above, it is hardly worth while to discuss 

 its applicability to the Bohemian and Saxon uraninites of which 

 no complete and reliable analyses have been made except perhaps 

 the single one by Ebelmen in 1843, which on re-calculation by 

 Blomstrand was found to conform to his view. It can hardly 

 be doubted that had Blomstrand been able to analyze material 

 from more than one quarry about Moss he would have seen 

 the impossibility of reconciling the discrepancies in composition 

 so as to admit of the application of one general formula. 



It is apparent notwithstanding the deficiency of earths 

 and one or two other discrepancies, that analysis XVII was 

 really made upon Cleveite as the label indicated. The den- 

 sity too corresponds exactly with that found by Nordens- 

 kiold.* From a comparison of analyses and reasoning which 

 cannot be here set forth for want of space, it is in the 

 highest degree probable that the Cleveite of Nordenskiold, the 

 Nivenite of Hidden and Mackintosh, f and the material of 

 analysis XVII are identical or represent slightly different stages 

 of alteration of one and the same original species. What this 

 species is is pretty clearly indicated by analysis XYIII where 

 the earths are in about the same proportion as in XVII, but 

 the U0 3 and U0 2 stand in a very different ratio. The mate- 

 rial of this was likewise from Arendal and presumably from 

 the precise locality of that of analysis XVII, since the pieces 

 were in one package without distinguishing labels. Its ex- 

 treme solubility^: compared with the other Norwegian uranin- 

 ites is shared by that of analysis XVII, by Cleveite, and by 

 Nivenite, and is to be explained probably not so much by ad- 

 vanced decomposition as by the preponderance here of a more 

 soluble yttrium-uranium compound. Whether this last Aren- 

 dal material is the same whence Cleveite and its American 

 representative have been derived by alteration, as seems most 

 probable, or not, it is in any event a true uraninite of more 

 basic character than any of the Norwegian thorium-uraninites, 

 and consequently conforms still less than those to the ortho- 

 uranate formula. 



Only traces of nitrogen were found in uraninite from Przi- 

 bram, Joachimsthal, and Johanngeorgenstadt. None of the 

 specimens contained zirconia, thoria, or other rare earths. 



* Geol. For. Forh., iv, 28, and Zeitschr. f. Kryst., iii, 201. 



f This Journal, III, xxxviii, 481. 



% In this connection it may be remarked that the greatest difference exists be- 

 tween the solubility of the Norwegian and the American uraninites. While 12 

 hours is more than sufficient to effect complete decomposition of any of the 

 former by very dilute H 2 S0 4 at 100° C, nine days is insufficient for the Con- 

 necticut mineral. 



