34 
Transactions of the JRoyal Society of South Africa. 
(2) The spectrum of the Uranyl Ion has already been given (I. c, p. 48). 
The following formula explains it in mathematical terms, viz. n = ^ = 
2113 + 66 N (in which N is 0, 1, 2, 3, and 4) : 
Calculated: 2113, 2179, 2245, 2311 and 2377. 
Observed : 2114, 2180, 2243, 2310 and 2381. 
As shown in the same paper the bands of the unionised solid salts can 
be calculated fairly closely from these figures by dividing by the sixth-root 
of the ratio of the molecular weight of the salt to that of U0 2 + + . Thus 
the bands of autunite are given by — 
V 2 x 270 
Calculated : 1937, 1997, 2058, 2118 and 2179. 
Observed : 1945, 2000, 2062, 2128 and 2190. 
I wish to thank Mr. T. P. Waites for the fine specimen of autunite in 
crystals large enough to permit observing the absorption-spectrum. 
