124 
THOMSON’S ANALYSIS OF GADOLINITE. 
crystallized, though imperfectly. The solu- 
tion gave the following characters with 
re -agents : 
Prussiate of potash : No precipitate. 
Caustic ammonia : A white precipitate, 
not soluble in an excess of the alkali. 
Caustic of potash : A white precipitate , 
soluable in an excess. 
Oxalic acid : No precipitate. 
Oxalate of ammonia : No precipitate. 
Benzoate of ammonia : No precipitate. 
Tincture of nutgalls : A white precipitate. 
Gallic acid : No precipitate. 
The white matter obtained was therefore 
glucina. 
The preceding analysis gave the constitu- 
ents of gadolinite as follows : — 
Silica. 6-22024-880Yttria 11 •00744-348Pro- 
toxide of cerium 1-430 5-720 Glucina 3*182 
12*728 Protoxide of iron 3*374 13*500 Platinum 
0*450 1*800 Moisture 0*247 1*088. Total 
25.991 104*064. 
Suspecting that the increase of weight in 
this analysis, which rather exceeds 4 per cent., 
might have been owing to the yttria not 
having been sufficiently ignited,* it was 
repeated in the following manner : — 
A. 30 grs. of the finely powdered mineral 
were boiled in a flask with nitro -muriatic 
acid till the whole was decomposed. The 
silica separated in the usual way, and most 
carefully washed with boiling distilled water, 
weighed after ignition, 7*3 grs. It was beau- 
tifully white and pure. 
B. The residual solution w*as mixed sal- 
ammoniac, and evaporated to dryness. 
When again dissolved only a mere trace of 
platinum remained. 
C. The solution was now mixed with 
oxalic ^acid, and, to ensure the precipitation 
of any manganese that might exist in the 
mineral the whole was evaporated to dryness. 
The white matter remaining undissolved on 
digesting the mass in water, after being well 
washed and ignited, weighed 15 grs. It was 
of a light-yellow colour. 
D. It was dissolved in nitric acid. The 
solution was evaporated to dryness, the 
residue dissolved in a small quantity of water, 
and crystals of sulphate of potash were 
allowed to remain in the solution for a week. 
The clear liquid was then drawn off, and the 
white matter, after being well washed in a 
saturated solution of sulphate of potash, was 
dissolved in dilute nitric facid, and precipi- 
tated by ammonia and boiled in a flask, to 
ensure the complete separation of the sulphu- 
ric acid. The peroxide of cerium, after 
ignition, weighed 1*400 grs. = 1*3 grs pro- 
toxide. 
E. The sulphate of potash solution from 
(D) was mixed with a solution of carbonate 
of ammonia in great excess. To what 
remained after the clear liquid had been drawn 
off fresh solutions were added, and this was 
repeated six times before the whole was dis- 
solved. There remained only a few flocks, 
not weighing 0*01 gr. As they became black 
* We had found that the carbonate of cerium 
is not decomposed by exposure to a pretty 
strong red heat. 
when dried they probably consisted of oxide 
of manganese, but the quantity was too small 
to permit the use of re-agents to determine 
its nature. 
The 15 grs. of white matter were therefore 
composed of Yttria 13*6, Peroxide of ceri- 
um 1*4 Manganese, trace total 15*0 
F. The oxalic solution from(C.)was preci- 
pitated by ammonia, and the precipitate 
washed to get rid of the oxalic acid. It was 
then dissolved in muriatic acid. To separate 
the glusina from the iron, caustic potash, 
and then carbonate of ammonia were tried ; 
but neither of these methods was found to 
answer. The separation was therefore accom- 
plished by the same process as in the former 
analysis. There were obtained Peroxide of iron 
4*53 4077 protoxide Glucina 3*47. 
This analysis'gives the composition of ga- 
dolinite as follows : — Silica 7*300-24*33 Yttria 
13*600-4*533 Protoxide of cerium 1*300-4*33 
Glucina 3*470-11*60 Protoxide of iron 40*77- 
13*59 Platinum trace-trace Manganese trace- 
trace Moisture 0*296-098. Total30*043 100*17- 
This analysis gives us the' constituents of 
gadolinite as follows: — 12*16 atoms silica 
8*06 yttria 0*88 protoxide of cerium 3*91 
glucina 3. protoxide of iron. 
Were we to suppose the protoxide of iron to 
be an accidental ingredient, we might consider 
gadolinite as composed of 2 atoms silicate of 
yttria, 1 atom silicate of glucina and cerium, 
or we might consider it as composed of 1 
atom silicate of cerium, 4 atoms silicate of 
glucina, 8 atoms silicate of yttria. 
If the protoxide of iron be an essential con- 
stituent, the oxide of serium, glucina, and 
protoxide of iron must be in the state of 
disilicates. 
II. EXPERIMENTS ON YTTRIA. 
The neutral colourless sulphate of yttria 
was dissolved in water, and the solution, 
when treated by re-agents, exhibited the 
following properties : — 
1. Prussiate of potash : A white chalky 
precipitate. 
2. Ammonia : A white precipitate, hot 
soluble in excess. 
3. Potash : A white precipitate, not solu- 
ble in excess. 
4. Alkaline carbonates : A white precipitate 
soluble in excess. 
5. Infusion of nutgalls O. 
6. Gallic acid : O. 
7. Tincture of nutgalls : White, merely 
from the alcohol. 
8. Alcohol: White. 
9. Chromate of potash ; Yellow. 
10. Bichromate of potash : O. 
11. Hydriodate of zinc : O. 
12. Sulphate of potash : O. 
13. Oxalic acid : A white precipitate. 
14. Oxalate of ammonia: A white preci- 
pitate. 
When a solution of muriate of yttria was 
exposed to the galvanic action, chlorine was 
given out at the negative pole, and a small 
quantity of some other gas, (probably hydro- 
gen) at the positive pole. A quantity of 
gelatinus matter collected round the nega- 
tive wire. 
