Art. iir ] Watson, Occnrroice of UranopJiane. 27 



a lens, a small amount of the yellow mineral from particles of 

 the granite and other possible impurities for chemical analysis. 

 O. 1 3 10 gram of the powder was used, which gave : 



Total .... 98.91 



As Packard remarks, the above result clearly indicates that 

 the material was not entirely free from impurities. A second 

 weighed portion was accordingly selected amounting to 0.5120 

 gram of the dull lemon- or sulphur-yellow mineral and treated 

 with HNO:; , which after digestion left a residue weighing 

 0.2460 gram, yielding 0.2660 gram for analysis. This gave: 

 U (U 04)0 61. 28, corresponding to 60. 14 per cent of UO.2 ; CaO 

 6.01. 



Accepting then the percentages of Si02 and Hg O in the 

 first analysis, and those of UO3 and CaO in the last, as repre- 

 senting the composition of the mineral; and disregarding the per- 

 centages of Fe.2 0;5 , Alo O.} , MgO and P.^ Oj , and recalculating 

 the four essential oxides to a basis of 100, the ratios become: 



III 

 I. 

 CaO . . . 6.01 



U0-* . . . 60.14 



SiO--' . . 18.55 



H'^O . . . 13.28 



97.98 100 



I. Analysis of uranophane from Stone Mountain, Geor- 

 gia, from which the small percentages of AI2 Oo , 

 Fe., O.i , MgO and P._, O5 are omitted. 

 II. Analysis I recalculated to a basis of lOO. 

 III. Molecular ratios of II. 



The molecular proportions given under column III cor- 

 respond to the formula Ca0.2U03 . 3Si02 + 7H2 O, which indi- 

 cates one part more of SiOo and H2 O than is required by the 

 formula for uranophane, Ca0.2U0;i .2Si02 +6H2 O. The dis- 



