A System of Instruction in the Practical Use of the Blowpipe Part 50

(8) Special reactions. With carbonate of soda and nitre gives the manganese reaction.

COPPER.

Mineral. Native Copper

Formula. Cu.

Behavior

(1) in gla.s.s-bulb. --

(2) in open tube. --

(3) on charcoal. Fuses to a brilliant metallic bead, which on cooling becomes covered with a coating of black oxide.

(4) in forceps. Fuses and colors the outer flame blue.

(5) in borax. In the oxidizing flame dissolves and then gives the copper reactions.

(6) in mic. salt. As in borax.

(7) with carb. soda. --

(8) Special reactions. --

Mineral. Vitreous Copper

Formula. Cu^{2}S.

Behavior

(1) in gla.s.s-bulb. --

(2) in open tube. Evolves SO^{2} and, when pulverized and gently heated for some time is converted into CuO.

(3) on charcoal. Fuses to a bead, which spirts considerably and gives off SO^{2}. When pulverized and gently roasted, is converted into CuO.

(4) in forceps. --

(5) in borax. The roasted mineral gives the copper reaction, and sometimes also a slight iron-reaction.

(6) in mic. salt. As in borax.

(7) with carb. soda. In the reducing flame is decomposed, forming NaS and metallic copper. If the former be cut out and laid upon silver, it gives the sulfur reaction.

(8) Special reactions. --

Mineral. Copper pyrites

Formula. [,Cu=][,,,Fe=].

Behavior

(1) in gla.s.s-bulb. Decrepitates, sometimes gives a sublimate of sulphur and becomes bronze colored on the surface.

(2) in open tube. Evolves SO^{2} and is finally converted into a dark red mixture of Fe^{2}O^{3} and CuO.

(3) on charcoal. Fuses readily with much ebullition and is magnetic on cooling.

(4) in forceps. --

(5) in borax. As the preceding; but when the copper has been removed by reducing on charcoal, the bead shows a strong iron color.

(6) in mic. salt. As the preceding, but the color in the oxidizing flame is green, owing to the presence of iron.

(7) with carb. soda. Yields a bead of metallic copper and some magnetic oxide of iron which remains on the charcoal. The fused gives a sulphur reaction on silver.

(8) Special reactions. --

Mineral. Fahlerz

Formula. ([,Cu=][,Ag][,Fe][,Zn])^{4} ([,,,Sb][,,,As]).

Behavior

(1) in gla.s.s-bulb. Sometimes decrepitates, fuses, and when very strongly heated, gives a red sublimate of [,,,Sb] with [...Sb], also sometimes a black sublimate of [,Hg] and occasionally [,,,As].

(2) in open tube. Fuses and gives off thick fumes of SbO^{3} and SO^{2}, also generally AsO^{3}, leaving a black infusible residue. If Hg be present, it is sublimed and condenses in the tube in small drops.

(3) on charcoal. Fuses to a bead, which fumes strongly and incrusts the charcoal with SbO^{3}, and sometimes ZnO, which cannot be volatilized.

Emits a strong smell of a.r.s.enic.

(4) in forceps. --

(5) in borax. The residue obtained on charcoal thoroughly roasted gives a copper reaction, and when the latter has been removed by reduction upon charcoal, an iron reaction.

(6) in mic. salt. As in the preceding.

(7) with carb. soda. With this flux and a little borax yields a bead of metallic copper; on silver, the alkaline ma.s.s gives a sulphur reaction.