cosmic salt, with the application of heat, a white precipitate is obtained, which dissolves either colorless or yellowish, in microcosmic salt but the glass, when treated with tin in the reducing flame, on charcoal, assumes a dark greyish color on cooling, and behaves precisely like oxide of bismuth.

The artificially prepared metallic nickel, on a large scale, is not always free from bismuth; should an operator, therefore, wish to determine a small admixture of bismuth in the nickel, before the Blowpipe, he must mix one part of the finely divided sample with two parts of saltpetre, and treat on a platinum wire in the oxidating flame. The pyrognostic assay, which consists of potassa, oxide of nickel, and oxide of bismuth, is detached from the wire, and treated for some time on charcoal in the reducing flame. The oxide of bismuth is very readily reduced by this means; the metallic bismuth sublimes, and coats the charcoal with an oxide.

§ 10. URANIUM-U-Presence in the Mineral Kingdom.

Uranium, which is an exceedingly rare metal, occurs in nature in an oxidized state :

a. As friable and compact Hydrate of the Sesquioxide of Uranium, the last of which is mixed with Lime and Oxide of Lead; the two varieties are called Uran Ochre ;

b. As an Oxide, with Phosphoric Acid, and Phosphate of Lime, in Uranite [3 Ca O, P 05 + 2 (U2 O3, P 05) + 24 aq] mixed with [3 Ba O, P 03]; in an oxidized state, with Phosphoric Acid, and Phosphate of Copper, in Chalkolite-Green Uranite-[3 Cu O, P 05 + 2 (U2 O3, P 05) + 24 aq];

c. As Protoxide, with Titanic Acid, Lime, Oxide of Cerium, Protoxide of Manganese, Sesquioxide of Iron, Oxide of Tin, Water, and traces of Hydrofluoric Acid and Magnesia, in Pyrochlore, from Fredrikswärn-WÖHLER's analysis;

d. As Sesquioxide, with Tantalic Acid and Yttria, in Yellow Yttro-Tantalite [3 YO {T203]; and,

Ta 03
U2

e. As Protoxide, with Silicic Acid, and traces of Sesquioxide of Iron, Sulphide of Lead, and Oxide of Cobalt, in Pitch-BlendeUran-Pecherz-[3 U O, 2 Si O2]. Uranium is also found in

Pechuran, Uranvitriol, Uranbloom, Uranotantalum, Fergusonite, Euxenite, Polykras, and Thorite.

Examination for Uranium.

In the previously described minerals, with the exception of Chalkolite and Pyrochlore, uranium is determined by treating them in a powdered state with microcosmic salt, upon platinum wire, as well in the oxidating as in the reducing flame. See pages 92, 93, Table II.

Pyrochlore, on account of its containing a considerable quantity of titanic acid and iron, destroys the colors given by uranium in the reducing flame; the glass, upon cooling, becomes blood-red. In the oxidating flame, however, the microcosmic salt bead becomes greenish upon refrigeration, but is contaminated with yellow. When the substance contains only a small quantity of uranium, and much iron, the ferruginous reaction is given both with borax and microcosmic salt; therefore, the sample must be fused with bisulphate of potassa, the residue dissolved in water, nitric acid added to convert the iron and uranium into sesquioxides, and then carbonate of ammonia poured into the liquid for their separation,which is treated of under Iron.

If the mineral contains oxide of copper, as is the case with the Chalkolite, from Cornwall, a green glass is also obtained with borax and microcosmic salt, in the oxidating flame. As minerals containing prot- and sesquioxide of iron, and oxide of copper, without uranium, give a similar reaction to the above substances, when examined for this metal, they must be submitted to a different treatment. The substance is to be smelted with carbonate of soda and borax, with an addition of lead, upon charcoal in the reducing flame, until the whole of the copper is reduced and alloyed with the lead.

The glass, when cold, must be pulverized, treated with hydrochloric acid and water, the protoxides of uranium and iron, if present, converted into sesquioxides, by the addition of a few drops of nitric acid, and then carbonate of ammonia added in excess, and the subsequent part of the process conducted in the same manner as mentioned under the head of Iron. According to

LIEBIG, Uranium may be extracted from Pitch-blende—a variety of Uran Ochre-by the following process:-After heating the mineral to redness, and reducing it to an impalpable powder, it is digested in pure nitric acid, diluted with four parts of water, taking the precaution to employ a larger quantity of the mineral than the acid added can dissolve. By this process, the protoxide of uranium is converted into sesquioxide, which unites with the nitric acid, almost to the total exclusion of the iron. A current of sulphide of hydrogen gas is then transmitted through the menstruum, in order to separate lead and copper, the sulphides of which are always present in Pitch-blende. The solution is boiled to expel any free acid, and after being concentrated by evaporation, is allowed to repose. The nitrate of sesquioxide of uranium crystallizes out in flattened four-sided prisms, of a beautiful lemonyellow color.

The sesquioxide of uranium is employed in the arts, for imparting a fine orange color to porcelain, et cetera.

§ 11. COPPER-Cu-Presence in the Mineral Kingdom, and in the products of Smelting Furnaces.

This metal is found very abundantly in nature:a. Metallic, as Native Copper [Cu];

b. With Selenium, as well per se, as with other Selenides. namely, per se, in Selenide of Copper [2 Cu Se]; with Lead, in Selenide of Copper and Lead, and Selenide of Lead and Copper; and with Silver, et cetera, in Eukairite-from the Greek, signifying opportune; in allusion to its discovery just as BERZELIUS had completed his examination of Selenium-[2 Cu Se + Ag Se];

c. In the state of Sulphide, alone, and in combination with other metallic sulphides, namely, per se, as Vitreous CopperKupfer-glanz [Cu S], which generally contains traces of Iron and Lead; with Iron, in Purple Copper-Bunt-kupfererz-and Copper Pyrites; with Arsenic and Iron, in Tennantite [Eas} 2 As, 3S+ 2 (4 Cu, 4 S, 2 As, 3 S]; with Silver and a little Iron, in Argentiferous Copper Glance-Silberkupfer-glanz—[Cu S + Ag S]; with Arsenic, Iron, a little Antimony and Silver, in

4 Fe S

4 Cu

Fe S

Copper Blendes; with Tin, and a little Iron, in Tin Pyrites [Cu S+ Sn S];-the best formula for Tin Pyrites [2} Sn 2 S + 2 (Cu S) + Sn 2 S]-with Antimony, Silver, Iron, and Zinc, in Weissgilitigerz, a mechanical mixture of Brittle Sulphide of Silver with Grey Antimony, et cetera; with the Sulphides of the same Metals and Sulphide of Arsenic, in Grey Copper; with Antimony and Silver, in Antimonial Grey Copper; and with Lead, Antimony, and a little Iron, in Bournonite; with Silver, a little Iron and Arsenic, in Gansekothigerz; with Bismuth, in Cupreous Bismuth; and with Bismuth, Lead, a little Nickel, and Tellurium, in Siberian Needle Ore;

d. In an Oxidized state, either alone or in combination with other Metallic Oxides and Water, namely: as Suboxide, in Red Oxide of Copper-Rothkupfererz-[Cu2 O]; as Oxide with Sesquioxide of Manganese and Water, in Cupreous Manganese—

Kupfer-manganerz

[Cu o

3 (Mn2 Q3)
3 (HO)

} + 3 (2 Mn2 03, + 3 (H 0) ] ;

and as an Oxide, with a little Peroxide of Manganese, Iron, and Water, in Native Oxide of Copper [Cu 0];

e. As an Oxide, in combination with Chloride of Copper in Atacamite [Cu Cl + 3 (Cu O) + 6 aq ];

f. In an Oxidized state, with Acids, either alone or with other Metallic Salts, or Earths, and Water, thus :

1 With Carbonic acid and Water, in Blue Carbonate of Copper -Azurite-[2 (Cu O, C 0o) + Cu O, H 0]; and in Malachite [2 (Cu O) C 02 + H 0];

2 With Arsenic Acid and Water, in Condurrite [6 (Cu 0) As 054 aq]; in Euchroite [4 (Cu 0) As 05 + 7 aq]; in Erinite [5 (Cu O) As 05 + 2 aq]; in Prismatic-Copper Mica [8 (Cu 0) As 05 + 12 aq]; and also with Alumina, in Liroconite-Octohedral Arseniate-[2 (Al2 03, 3 H 0) + 3 (4 Cu O As 05, 8 H 0)];

s With Phosphoric Acid and Water, in Libethenite [4 Cu O, PO5 + 2 aq]; and in Phosphoro-chalcite-Pseudo-Malachite[5 Cu O, P 05+ 5 aq];

• With Sulphuric Acid and Water, in Native Blue Vitriol [Cu O, S 03 + HO+ 4 aq];

5 With Chromic Acid and Chromate of Lead, in Vauquelinite; 6 With Silicic Acid and Water, in Dioptase (3 Cu 0, 2 Si 0o + 3 aq]; with Silicic Acid, Water, and a little Carbonic Acid, in Chrysocolla; and with Silicic Acid, and Silicate of Alumina, in Allophane.

Further, Copper is not only found per se, in scoriæ, et cetera, produced in the smelting of Cupreous Ores, but very often as a secondary constituent in the Slags from furnaced Argentiferous and Plombiferous minerals. It is found:

a

Metallic, in pure Gaarkupfer,—the product of the third smelting of Cupriferous Ores-and in combination with other metals, in Schwartzkupfer-second product; in the Frischstücken -the Argentiferous Leads, obtained in the refining of Copper Ores for Silver; in the Saigerdörnern—the residues which remain after extracting the lead from the Darrlinge, and which yield a crude copper on being subjected to a process of smelting; in the Darrlingen-eliquated coppers, from which the silver has been sweated out by lead; and in Cupriferous Workable Lead;

с

b With Sulphur, per se, and also with Sulphides, exempli gratia, in Rohstein, Bleistein, Kupferstein, Kupferleg-one of the products produced by smelting the roasted stein, which is obtained by smelting roasted Bleistein with Quartzose Copper Ores, with Blestein Slags, and Quartz-and in different Tuttys; In an Oxidized and Vitreous state, in all the slags which are obtained in the manufacture of Crude Copper, and in the refinement of Copper for Silver-Copper is also met with in Fahlerz, Kupferkies, Kuperwismutherz, Zinnkies, Cuban, Nadelerz, Cuproplumbite, Polybasite, Brochantite, Dihydrite, Ehlite, Tagalite, Thrombolite, Chalkolite, Mysorine, Aurichalcite, Klinoklas, Olivenite, Volbortite, and Kieselkupfer.

Examination for Copper.

This examination is very simple, and so certain, that its presence or absence, in any combination, can be determined in a short time.