UR A ( 454 ) UR A
86.5 Uranium in the ftate of fub-oxyd2.5 Black oxyd of iron6. Sulphuret of lead5. Silex
100.o
Of thefe ingredients the two Iaft appear tohe only cafual, for in an analylis by Lanrpadius,of a Specimen of this mineral from Saxony, ,there were obtained only uranium and iron ;in another there was a flight admixture of cop-per pyrites.
It occurs in veins in primitive mountains,mixed with ores of lead and fdver, with copperpyrites, iron ochre, and cobalt. It is found atJoachimfthal in Bohemia ; Johanngeorgenftadt,in Saxony; and Konglberg in Norway .
It is diltinguilhable from blende, with whichit was formerly confounded, by its fpecific gra-vity, and fracture, as well as chemical charac-ters.
Sp. 2. Micaceous Uranium. Uran -glimmer>Wern. Ur a tie micace, Broch.
Its ufual colour is grafs green of more or lefsintenfity, whence it pafles on one hand togreenifh lilvery white, and on the other to ful-phur yellow. It occurs fometimes as a fuper-ficial cruft but more ufually cryftallized in theform of rectangular tables; thefe tables arefometimes fo thick in proportion to their otherdimenfions as to approach to the cube, andfometimes two oppofite terminal planes are fodeeply bevilled on all their edges as to give theentire cryftal the appearance of a truncated oc-tohedron; the cryftals are generally very fmall,and cellularly aggregated; the terminal planesare ftriated, the lateral ones are finooth; theexternal luftre is more or lefs fhining; the in-ternal is gliftening and pearly; the fracture isftrait foliated in a Angle direction. It is tranf-lucent, foft, not brittle, but eafily frangible.Sp.gr. 3.12.
It is foluble in nitric acid without effervef-cence, and communicates to it a yellow colour.The yellow variety of this mineral appears froman allay by Klaproth , to be pure oxyd of ura-nium; the green varieties contain a little oxydof copper, to which that colour is owin£.
It occurs in veins of ironftone in primitivemountains, accompanied by the other ores ofthis metal, and fometimes by cobalt, and arfe-niat of copper. It is found at Carrarach inCornwall, Eibenltock in Saxony , Safka in the
* Klapr. Aturtyt. J
Bannat, and St. Symphorien near Autun iaFrance .
Sp. 3. Ochery Uranium. Uranokhr , Wern.Qcre d'Urane. Broch.
Its colour is ftraw-yellow palling into orangeand greenifh yellow. It occurs fuperficial, dif-feminated, and mallive; it is dull or flightlyglimmering; its fracture is earthy palling^intofmall and imperfectly conchoidal. It is opake,foft, fometimes even friable; is brittle andmeagre to the touch. Sp. gr. — 3 o
1 he yellow varieties, according to Klaproth ,are pure oxyd of uranium, the orange colouredcontain a fmall admixture of iron.
It occurs with the other ores of uranium.
§. 2. AJfay and Analyfs.
The analylis of the ores of uranium is fuffi-ciently Ample. The only fubftances that havehitherto been found in natural mixture or com-bination with this metal, are lead, iron, copper,fulphur, and lilex, which may all be feparatedin the following manner. b
a. Let the ore be digelted with moderatelydilute nitric acid, by which the greater part ofit will be taken up; the refidue being walhedand dried is to be gently ignited, by which thefulphur will be burnt off; what remains afterignition is to be digelted with dilute nitric acid,and the infoluble portion is Jilex.
b. To the nitric folution* and wafhings mixedtogether, is to be added fulphat of foda as longas any precipitate falls down; this when col-lected on a filter, walhed and dried, is fulphatof lead.
c. The remaining folution is to be totallydecompofed by caultic fixed alkali, at a boilingheat, and the powder thus obtained is to bedigelted in caultic liquid ammonia till the wholeof the copper is taken- up. The ammoniacalfolution being then flightly fuperfaturated bylulphuric acid, the copper may be obtainedeither in the metallic Bate by means of a barof iron or zinc, or in the ftate of brown oxyd,by boiling with caultic fixed alkali.
d. The refidue of the precipitate c. after ex-traction of the copper, is to be evaporated todrynefs two or three times with nitric acid, andis then to be gently digelted in dilute nitric acid,which will take up the uranium, leaving theiron behind in the Itate of per-oxyd.
e. The nitrat of uranium being boiled withcaultic fixed alkali the whole of the uranium isprecipitated as pure yellow oxyd.