204 BLAIR— URANIUM AND VANADIUM [April 17, 



drops of hydrogen peroxide added. If the Hquid becomes brownish 

 yellow in color it shows an excess of vanadic acid. If it does not 

 it is better to take a fresh portion and add a solution of vanadic acid 

 in nitric acid. The amount to be added can be judged by the appear- 

 ance of the precipitate of ammonium uranyl vanadate formed in the 

 first instance. 



Second Method for the Determination of Uranium. 



In the presence of large amounts of alumina and oxide of iron 

 an extremely accurate separation of uranium may be made by using 

 the reaction suggested by Gooch & Havens,- by which aluminum 

 chloride is precipitated in a crystalline form free from iron in a solu- 

 tion of equal parts of ether and the strongest hydrochloric acid satu- 

 rated with hydrochloric acid gas. Havens^ has shown that this 

 method gives a separation of alumina from beryllium, zinc, copper, 

 mercury and bismuth. I have found that it gives an excellent sepa- 

 ration from uranium and vanadium and the method as worked out 

 is as follows : 



Treat two grammes of ore as directed in the method described 

 above for the determination of vanadium and after evaporating the 

 hydrochloric acid solution to syrupy consistency, transfer it to a 

 narrow graduated beaker of about 100 c.c. capacity, using concen- 

 trated hydrochloric acid to wash all the solution from the larger 

 beaker. The liquid should not exceed 20 c.c. to 25 c.c. in volume. 

 Cool the liquid to about 15° C, and saturate it at that temperature 

 with hydrochloric acid gas. The gas may be generated from rock 

 salt or ammonium chloride in lumps and strong sulphuric acid and 

 the current of gas should be constant and of considerable volume. 



When the gas is no longer absorbed but passes freely through 

 the liquid in the beaker note the volume and add an equal volume 

 of ether. Saturation of the liquid generally increases the volume 

 about one fifth and to obtain a satisfactory separation of alumina 

 the volume of ether added should equal the volume of the saturated 

 solution. Continue passing the gas until the solution is again satu- 

 rated, being careful to keep the temperature of the solution close 



' Gooch, " Methods of Chemical Analysis," p. 204. 

 ^ Loc. cit., pp. 216, 217. 



