OBSERVATIONS ON URANIUM. 



demispherolds, the deflected position of which, imperfectly 

 terminated at one of the extremities, exhibits at the other 

 the very decided reentering* angles, that characterise the 

 lieraitrope. 



XII. 



Remarks on the Pechbfende, an Ore of Uranium: by Mr, 

 Vauquelin*. 



"^9 



.R. de Lannoy, a dealer in minerals, and a skilful con- Mineral resem- 

 noisseur in this branch of natural history, had in his col- ^!'"? S^^^^'^" 

 lection several specimens ot a black, shining, compact, blende, 

 heavy mineral, with a conchoidal fracture, the nature of 

 which he did not know. Mr. Haiiy, to whom he showed 

 it, was in doubt between gadolinite and pechblende, which 

 in fact it resembled more than any other substance. 



Having given me a piece of it to subject to chemical ana- proved to be 

 lysis, I soon found, that it was pechblende, or sulphuret of *^*^'*"*^' 

 uranium. Though the experiments, by which I found what 

 it was, have nothing new in themselves, I shall relate some 

 of them, because they afforded me an opportanity of mak- 

 ing a few remarks on the state in which iiranium exists in 

 this ore, and on the combinations it is capable of forming 

 with oxigen. 



The pechblende reduced to powder, and digested in mu*- Treated with 

 riatic acid moderately concentrated, dissolved without any muriatic *cid. 

 perceptible effervescence, only a smell of sulphuretted hi- 

 drogen gas was emitted. 



The solution had a very deep dirty green colour. Di- Solution fil- 

 luted with water and filtered, it left on the paper a small tered, 

 quantity of residuum; which, when washed and dried, ex- 

 hibited all the properties of silex mixed with a little sul- 

 phur. 



During the evaporation, and more especially during the & etap^rated. 

 cooling, this concentrated solution deposited crystals of 

 muriate of lead. These I separated by adding rectified alco- 



* Annales de Chipi«, vol. LXVIII, p. 277. 



hoi. 



