OOLUMJSIUM.

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acid.—The solution of this Oxide in nitric acid does not yield a bl-ueprecipitate with ammonia, unless in small quantity from the acciden-tal presence of copper, and may thus be distinguished from solutionsof the green ores of copper.—It docs not, like muriate of copper, com-municate a greenish blue color to flame.

(Geological situation and Localities.J These crystals or platesare usually disseminated in the fissures, or attached to the surface, ofother minerals, especially the compact brown oxide of iron, black ox-ide of uranium, quartz, hornstone, granite, mica slate, indurated clay,&c.

Tt is found in Cornwall ; at Johanngeorgcnstadt, &c. in Saxony ;in France , Hungary , &c.—In the United States , it has probably beenobserved in .Maryland ; near Baltimore .

3. earthy ghee's oxide of uramum.* Its color is greenishyellow, sometimes sulphur or straw yellow. The shade of green,which is not always very obvious, may often be brought to view bymoistening the surface; and sometimes, from accidental impurities,the yellow is mixed with a shade of brown or red.

It is sometimes in the state of a powder, forming a mere crust;and sometimes in small masses, either friable, or somewhat induratedwith an earthy or uneven fracture, nearly or quite dull.

(Localities.J It most frequently accompanies the other ores ofuranium ; and of course has the same localities.—In the UnitedSlates, this variety is supposed to exist in Maryland , near Baltimore ;—and in Maine , at Brunswick.

GENUS XXII. COLUMBIUM . JUrcHErv .f

Columbium may be extracted in the state of a white oxide from itsores; and this oxide may be reduced by a strong heat into a globulemoderately hard, with a metallic lustre at its surface, and a dullgrayish black fracture. This metallic substance is by the action ofacids again converted into a white oxide.

This Oxide has a spec. grav. of 6.50. Its color is not changed ina red heat, nor does it communicate any color to borax, when fusedwith it. It is nearly insoluble in the nitric, muriatic, and sulphuricacids. Its proper solvent is potash or crystallized carbonate of pot-ash. 'When fused with eight times its weight of carbonate of potash,a mass is obtained, which is soluble in water. If any of the threepreceding acids be added to this solution, the oxide of Columbium isprecipitated, and is not redissolved by an excess of acid. But the

* Urane oxide terreux. IIjxt. fran ocker. AYiaixnt. frail ochre. Jam.

•J- Tantalum. F.klukiuj.