414 



Sir W. Crookes. 



(3) The salt was treated in the same way as No. 1, except that the 

 excess of water and acid were not driven off. 



(4) A small quantity was heated for some time on a water-bath till 

 it was thoroughly dry. It was then powdered and put in a cell. 



(5) 50 grains were put in a glass cell and heated on a water-bath to 

 about 75° C. till it had dissolved in its water of crystallisation. 



(6) 50 grains in a glass cell were heated on a sand-bath to about 

 230° C. The water of crystallisation having been driven off the salt 

 fused, and on cooling remained a hard, yellow, glassy mass. 



(7) A similar quantity of the same salt was heated to a little above 

 230° C. till it commenced to decompose. 



(8) A similar quantity was heated more strongly, till about half the 

 nitrate had decomposed. 



(9) The same quantity was heated till decomposition was complete. 



(10) As a standard, some of the same lot of commercial uranium 

 nitrate from which these lots were taken was put in a cell. 



These ten cells were placed in a lead screen apparatus, and a sensi- 

 tive plate was exposed to their influence for twenty-four hours. On 

 development there was not much difference between any of the impres- 

 sions, that under No. 9 being a little the strongest. 



Thus it appears that no modification of physical or chemical con- 

 dition materially affects the radio-active property of a uranium com- 

 pound when, to begin with, the salt experimented on possesses it ; 

 other imilar experiments show that, starting with an inactive uranium 

 salt, nothing that can be done to it will cause it to acquire this property. 

 It is therefore evident that, as I had suspected, the radio-active pro- 

 perty ascribed to uranium and its compounds is not an inherent 

 property of the element, but resides in some outside body which 

 can be separated from it. 



Having by repeated crystallisation succeeded in preparing a photo- 

 graphically inactive uranium nitrate, I started experiments with 

 several pounds of the commercial salt to ascertain the readiest means 

 of separating from it the active body. 



13. Into a stoppered cylinder I put 1 lb. of crystallised nitrate and 

 poured on it a pound of methylated ether, sp. gr. 0*72. The salt 

 easily dissolved on shaking, and after a few hours the whole of the 

 crystals had disappeared, leaving at the bottom of the cylinder 1000 

 fluid grains of a heavy aqueous solution. I separated the aqueous 

 solution from the ethereal solution, and evaporated it to dryness to 

 remove traces of ether. The ethereal solution was allowed to evapo- 

 rate spontaneously. Equal quantities of the soluble and the insoluble 

 in ether I put into glass cells and added sufficient dilute nitric acid to 

 dissolve the salt, and then evaporated each lot to dryness on the 

 water-bath. When dry the two cells, and a third containing some of 

 the original nitrate, were put on a sensitive plate for twenty-four hours. 



