410 S. RADCLIFF. 
The sulphate mixture (c) contains about 37% of rare earths 
of the composition :— 
Thorium oxide wie ... 13°2 per cent. 
Oerium oxide ... i .. 44°0 cA 
La and Dy oxide a oc | 4256 . 
Yttrium oxide Sy. a.) SLAee 
The activity of these rare earths increases at about the 
rate expected from the presence of actinium and almost 
the whole of the actinium in the ore appears to be carried 
down with the precipitated lead and barium sulphates. 
This is in accord with the observation of Debierne,* who 
states that actinium can be removed from a solution by 
precipitating barium as sulphate in it. 
As ten tons of concentrates yield only 40 kilos of sulphates, 
the concentration of the actinium is very considerable. 
The sulphates, which have the composition:— 
Lead sulphate a ... 69°24 per cent. 
Barium sulphate ... vt P50 xs 
Ferric oxide ... che iey ly eako a 
Silica: |. a eA wa - 10782 ~ 
Titanic oxide a Rye) ae 
Rare earths ... at Pe ieee Hl) < 
are treated as follows:— 
1. They are fused in an iron crucible with excess of 
caustic soda containing some carbonate of soda; the melt 
is extracted repeatedly with hot water, and this removes 
the greater part of the lead. 
2. The insoluble residue is digested under a steam pres- 
sure of 90 fds. with an excess of carbonate of soda. 
3. The carbonate residue after washing is treated with 
dilute hydrogen chloride and the solution evaporated to 
1 C.R., 129, p. 593. 
