, 
1817] Thorina; a new Earth. 455 
I mixed it with sulphate of potash, which occasioned a precipitate, 
Before separating the yttria, I wished to prevent the oxide of man- 
ganese from being deposited along with it. For this purpose I fil- 
tered into the liquid a boiling solution of muriate of ammonia, in 
order to form a double salt composed of muriate of ammonia and 
proto-muriate of manganese, which would prevent this last oxide 
from being precipitated by the ammonia. The consequence was a 
bulky white deposite. I continued to pour in the salt till all precipi- 
tation was at an end. The precipitate was thrown upon a filter, 
washed, and dried. Perceiving that it was a substance different 
from any which I expected to find in gadolinite, I wished to prepare 
a greater quantity of it. But though I endeavoured with the greatest 
care to ascertain all the external differences which the specimens of 
gadolinite from Korarvet exhibited, and examined each of them 
separately, I could not obtain the smallest trace of the substance, 
though I had fallen upon pretty correct methods of separating it 
from yttria and oxide of cerium, even when it existed only in small 
proportions. I therefore deferred to a future opportunity further 
researches on this substance, without even mentioning it in the 
analysis of that variety of gadolinite, because I still considered its 
existence as problematic. Having found it again at Finbo, I en- 
deavoured to determine its properties more exactly; but as it happens 
here also that the same mineral does not always contain it, or that 
minerals which contain it are absolutely similar to those which do 
not contain it, I could not be sure at present of obtaining a new 
portion of it, without destroying. a great part of the specimens of a 
mineral which is very rare. I have thought it right, therefore, in the 
present uncertainty, to describe it such as I have found it, that if it 
be discovered hereafter in greater abundance, as it is probable it 
will, my statements may facilitate the means of separating and exa- 
mining it. I may state here, by way of apology for the imperfec- 
tion of this notice, that I have not had altogether half a gramme of 
this earth to make my experiments with. 
To obtain it from those minerals that contain protoxide of cerium 
and yttria, we must first separate the oxide of iron by succinate of 
ammonia. ‘The new earth, indeed, may, when alone, be precipi- 
tated by the succinates ; but in the analytical experiments in which 
I have obtained it, it precipitated in so small a quantity along with 
iron, that I could not separate it from that oxide. The deutoxide of 
cerium is then precipitated by the sulphate of potash; after which 
the yttria and the new earth are precipitated together by caustic 
ammonia. Dissolve them in muriatic acid. Evaporate the solution 
to dryness, and pour boiling water on the residue, which will dis- 
solve the greatest part of the yttria; but the undissolved residue 
still contains a portion of it. Dissolve it in muriatic or nitric acid, 
and evaporate it till it becomes as exactly neutral as possible. ‘Then 
pour water upon it, and boil it for an instant. The new earth is 
precipitated, and the liquid contains disengaged acid. By satu- 
