MANUFACTURE OF RADIUM MATIGNON 225 



Carnotite is a vanadiate of uranium and potassium, V2O5.2UO3.- 

 IC0.3H.0, of a yellow tint. It is rarely found in a pure state. 

 In the ITnited States carnotite impregnates the old porous sands, 

 giving them a pale yellow tint. The average mineral contains 1.5 

 to 2.8 per cent of uranium oxide with 3.5 per cent of the anhydrous 

 VoOg. These sands extend through immense tracts in the States 

 of Colorado and Utah in beds var3dng in thickness from y^ to 2 

 meters or more. 



Autunite, P2O5.2UO3.CaO.8HoO, or uranite, has been much ex- 

 ploited in Portugal, in the Province of Beire Baixa. This mineral 

 is prone to mechanical enrichment. 



THE EXTRACTION OF RADIUM 



To Mme. Curie and M. Debierne we owe the method for the ex- 

 traction of radium from uraniferous minerals. All the processes 

 since developed utilize in their main lines the methods instituted 

 by these two scientists. 



The Austrian Government, whose mine in Joachimstahl has been 

 long worked, extracts the uranium from the pitchblende by a 

 fusion of the pulverized mineral with sodium sulphate. Under 

 such conditions, the sulphate changes the uranium oxide into sodium 

 uranate, easily soluble in dilute sulphuric acid. During the fusion, 

 the radium, if not already in this state, is changed into an insoluble 

 sulphate which remains in the residue. It was these residues, 

 accumulated about the Austrian works, which served, we have 

 already seen, as the first material for the isolation of radium. 



We will now state the method used in America in the treatment of 

 carnotite. This method was applied on a very large scale, about 

 150 grams of radium resulting from the treatment of more than 

 750,000 tons of the active sand. Then we will indicate the modifi- 

 cations which were necessary for the treatment of pitchblende. 



TREATMENT OF THE AMERICAN MINERAL CARNOTITE 



The ore arrives at the works in sacks marked with figures which 

 indicate the richness in uranium determined approximately by means 

 of an a-ray electroscope. 



The principle of the method of reduction is very simple. The 

 sands impregnated with carnotite are treated with a warm solution 

 of hydrochloric acid which dissolves the carnotite with its elements, 

 vanadium, uranium, and radium. The addition of sulphuric acid 

 precipitates the insoluble barytes, always present, carrjnng along 

 with them all the radium asTadium sulphate. Since the presence 

 of barium is necessary in the subsequent stages of the process, some 

 is added if the mineral itself contains an insufficient quantity. 



