OBSEEVATIONS ON URAMIU51. 7I 



to a proper degree, afford neutral salts, which crystallize 

 each in its peculiar form, but all of a yellowish green colour. 



The yellow oxide on the contrary combined with these Salts of the 

 acids never forms perfectly neutral salts, and does not crys- neutral "nol '^' 

 tallize in distinct and regular figures. c/ystallizable. 



The green oxide does not dissolve in alkaline carbonates: The yellow- 

 but the yellow oxide does in large quantity, as Mr. Klaproth kSs'Tul^hi" 

 a rst observed. green does not. 



From these experiments it appears to me beyond a doubt, Two oxides of 

 that uranium is susceptible of two degrees of oxidation, yanium there- 

 and this is principally the object I had in view to demon- 

 strate here; one by .which it forms a deep green oxide, the 

 jother by which it yields an orange yellow oxide. It exists 

 in the first of these states in the pechblende ; and it is in 

 the second that it constitutes the yellow ore of uranium, 

 such as that which Mr. Champeux discovered in the envi- 

 rons of Autnn, in the department of the Upper Saone. 



The pechblende of which I have given the analysis ap- Oxide of the 

 pears to me to contain uranium in the first degree of oxida- 'I'st degree in 

 tion, for it dissolves in muriatic acid without any perceptible * 



evolution of gas. 



I even doubt whether the sulphur contained in this ore which is not a 

 be combined with the oxide of uranium, for the quantity is ^"^P'^^'^'*'' 

 extremely small in proportion to that of this metal; and am 

 more inclined to suppose, that it belongs to the lead, which 

 also exists in it. 



This reflection did not escape Mr. Klaproth, for he says Klaproth of a 

 in the second volume of his analyses: " I do not consider ^""''»'^opi- 

 the black ore of uranium as a sulphuretj but as a metal 

 combined with little oxigen. It is this nearly metallic state 

 of the ore, that occasions the evolution of nitrous gas while 

 it is dissolving in nitric acid." Mr. Klaproth however has 

 not distinguished two species of the oxide. 



These two oxides comport themselves with the acids and The oxides 

 alkalis nearly as the oxides of iron. Thus the green oxide a'la'ogons to 

 of iron uniting with acids saturates them perfectly, 3^^^^'°^"^^'*^"" 

 forms crystal iizable salts; and does not dissolve in alkalis. 

 The red oxide on the contrary, in its combination with 

 acids, which it does not saturate, forms uncrystallizable 

 salts; and it dissolves in concentrated bubcarboaates. 



From 



