454 Chemical Description of [Junz, 
a pea. Its most usual colour is pale red, similar to that of a mixture 
of carmine and white lead ; but it is sometimes white, or deep red, 
or nearly yellow. It is so soft that it may be easily scratched by the 
nail, and it may be easily detached from its matrix by the fingers. 
It then leaves a rough irregular cavity. 
This mineral occurs likewise in irregular amorphous masses of a 
reddish-brown colour, sometimes separate, sometimes surrounding 
gadolinite, or mixed with it so as to appear a part of it. It never 
shows any tendency to assume a regular figure, or a crystalline 
texture. 
I have made several analyses of this mineral, which have all given 
different results ; which shows that the relative quantities of its con- 
stituent parts are very variable. 
While analyzing a specimen of this mineral, which did not differ 
in its external appearance from other specimens, I found a new 
quantity of the same earth which had been extracted from the 
amorphous neutral deuto-fluate of cerium. I shall state briefly this 
experiment. 
Twenty-two parts of the pulverized mineral were treated with 
sulphuric acid, which decomposed it, with the exception of 3°5 
parts. The solution was mixed with sulphate of potash, to separate 
the oxide of cerium. It weighed two parts. I then added caustic 
ammonia. ‘The precipitate which fell, being heated to redness, 
weighed 15°5 parts. I poured muriatic acid on it, which readily 
dissolved a portion of it. ‘The residue was only dissolved by means 
of a long digestion. The liquid was evaporated to dryness by means 
of a gentle heat, in order to drive off the excess of acid. I then 
poured water over it, which dissolved the muriate of yttria. The 
residue was dissolved in muriatic acid, and the liquid was saturated 
-by caustic ammonia as accurately as possible. I then added water, 
and caused it to boil. A white gelatinous precipitate fell, which was 
collected on the filter. The liquor that passed through the filter was 
again saturated by caustic ammonia, and heated to ebullition, which 
occasioned the precipitation of a new portion of the same earth. 
When washed and slightly dried, it weighed seven parts. In the 3°5 
parts of yttria separated from the 15:5 parts 1 found, by means of 
caustic potash, a small quantity of alumina; the weight of which, 
however, I did not exactly determine. 
Particular Examination of the new Earth. 
While I was examining the composition of gadolinite during the 
summer of 1815, I obtained in one of my analyses a peculiar sub- 
stance, amounting to 30 per cent. of the weight of the mineral, 
and which possessed properties different from the other earths. It 
was absolutely similar to the substance just found at Finbo. 1t was 
separated from gadolinite in the following manner :—The mineral 
having been dissolved in nitro-muriatic acid, the filtered solution 
was saturated by caustic ammonia, and precipitated by succinate of 
ammonia, having a slight excess of acid. The liquor being filtered, 
