Hillebrand — Occurrence of Nitrogen in Uraninite. 385 



existed and his U0 2 being moreover much too low. A re- 

 examination of the Norwegian mineral seemed desirable, and 

 thanks to Professors W. C. Brogger and A. E. Nordenskiold, 

 who kindly furnished material from several quarries about 

 Moss and from Arendal, this was rendered possible. The 

 results were surprising and established beyond question that 

 the formula found by Blomstrand was purely accidental, that 

 the mineral from different quarries varied in composition and 

 in such a manner that it was inadmissible to suppose that the 

 occurrence analyzed by him represented the pure material 

 from which the others might have been derived by alteration. 

 The most surprising discovery, however, was that nitrogen is 

 an integral component of most uraninites and possibly of all, 

 in quantities ranging from mere traces up to over 2*5 per cent. 



The nitrogen is set free from the mineral as nitrogen gas by 

 the action of a non-oxydizing inorganic acid, and by fusion 

 with an alkaline carbonate and probably also caustic alkalies in 

 a current of C0 2 . As obtained by the use of acids the gas is 

 colorless, odorless, a non-supporter of combustion, unchanged 

 by mixture with air, neutral to litmus papers, not absorbed by 

 caustic alkalies, and insoluble in water, at least its coefficient 

 of absorption is so small as to be inappreciable without 

 elaborate experimentation. When subjected in a eudiometer 

 to the ordeal prescribed by Bunsen * there results no altera- 

 tion in volume, other than that caused by the union of the 

 hydrogen and oxygen added. 



This evidence, while fairly conclusive as to the nature of 

 the gas, was purely negative, and proof of a more positive 

 character was sought. Nitric acid is formed from a moist 

 mixture of the gas with pure oxygen by long continued 

 passage of the electric spark, and ammonia is produced by the 

 so-called silent discharge through a mixture of the gas with 

 three volumes of electrolytic hydrogen. The contraction 

 produced in the latter case could be measured by cubic centi- 

 meters, and water used as an absorbent of the ammonia 

 colored red litmus paper deep blue, besides giving a strong 

 ammonia reaction with Nessler's reagent. With dilute hydro- 

 chloric acid as an absorbent there was obtained an abundant 

 precipitate of ammonium platinic chloride. In a Geissler 

 tube under a pressure of 10 mm and less the gas afforded the 

 fluted spectrum of nitrogen with great brilliancy. 



Special attention was paid to the estimation of U0 2 , or 

 more properly of the oxygen required to effect complete 

 oxidation after solution of the mineral in sealed tubes with 

 sulphuric acid. It was found that concordant results were 

 only to be obtained when the tubes were filled with CO a from 



* Gasometrische Methoden, 2d ed., pp. 13 and 74. 



