RECOVERY OF ACTINIUM AND IONIUM FROM OLARY ORES. 409 
state approaching purity, and methods for its complete 
isolation remain to be devised; the progress of the separa- 
tion can of course be followed by means of the electroscope. 
Unfortunately actinium preparations frequently show little 
or no activity initially, and it is necessary to keep them 
for some weeks in order to observe the characteristic rise 
of the activity with time. 
The uranium concentrates as received for treatment 
contain between three and four per cent. of rare earths, 
the mixture having the composition :— 
Thorium oxide se ... 0°32 per cent. 
Cerium oxide on ... 27°60 ae 
La and Dy oxide... ... 46°60 & 
Yttrium oxide ot ne Zora 
99 
These earths distribute themselves in three of the works’ 
products. They are found :— 
(a) In the hydroxides of the elements of the iron 
group which are precipitated by carbonate of soda 
during the extraction of the uranium. 
(b) In the uranium oxide recovered. 
(c) In the mixture of impure sulphates of lead barium 
and radium recovered in the course of the extrac- 
tion of the radium. 
The uranium oxide contains only traces of rare earths, 
and as these are only very feebly radioactive, they have 
not been examined in detail. 
The hydroxides (w) when washed and dried contain about 
5% of a mixture of rare earths of the composition :— 
Thorium oxide aoe Bee, io per Celt. 
Cerium oxide ... snd ses, O47 os 
Paand Dyroxde 7; 87280.) 263 NA 
Yttrium oxide ee ca Ten 
99 
These rare earths appear to be actinium free. 
