flame given by lithia is durable, whilst that afforded by strontia is evanescent.

Lime acts as strontia.

Potash, treated as soda, gives a purplish light; but the re-actions of potash and soda with oxide of cobalt are the best tests of their presence, combined with the peculiar light afforded by soda.

ON THE INDICATIONS GIVEN BY THE MOST COMMON OF THE MINERALS ON BEING TREATED BY THE BLOW-PIPE, AIDED BY FLUXES.

MINERALS OF COPPER.

Sulphuret of Copper-Alone, on charcoal, gives off sulphurous acid, fusing readily in the outer flame. In the inner flame it is covered with a crust, and does not fuse.

In the open tube sulphurous acid is disengaged, but no sublimate is produced. The residue, treated with soda and borax, gives a button of copper.

Argentiferous Sulphuret of Copper.-Alone fuses easily, giving off sulphurous acid. Cupelled with lead, on bone-ash, it leaves a large bead of silver, and the cupel appears a blackish green.

Sulphuret of Antimony and Copper, Bournonite.Alone, in the open tube, gives off the antimonial smoke, with an odour of sulphurous acid. A slip of Brazil-wood paper, on being placed within the tube, is bleached.

On charcoal, a deposit of antimony, but no trace of lead. The bead diminishes in size, becoming grey,

and semi-malleable.

of copper.

Fused with soda, it gives a grain

Copper Pyrites, Sulphuret of Iron and Copper.-Alone, on being heated, blackens, becomes red by cooling, and fuses more easily than the sulphuret of copper, finally giving a bead attractable by the magnet. This bead is brittle, and reddish-grey in the fracture. If after a long exposure to the oxidating flame, it be treated with a small quantity of borax, a regulus of copper is obtained.

In the open tube, much sulphurous acid is given off. With soda, globules of iron and globules of copper are obtained, provided the ore has been sufficiently roasted.

Sulphuret of Tin and Copper, Tin Pyrites.-Before the blow-pipe it becomes, by roasting, covered with a snow-white powder, which is oxide of tin. The white powder also encircles the globule to the extent of about two lines.

In the open tube, sulphurous acid is given off.

Needle-ore, Aikenite.—Alone, it fuses, giving off vapour, which coats the charcoal snow-white, slightly yellowish on the interior edge, finally giving a metallic bead resembling bismuth.

In the open tube it gives off a white smoke, one part of which is fusible, and the other volatile. The first part is converted by fusion into limpid drops, which become white by cooling; there is also an odour of sulphurous acid. Treated by fluxes, the resulting bead of bismuth gives the re-action of copper. After a long blast, a grain of copper may be obtained, which by cupellation with lead gives traces of silver. The fusible white

smoke, at the commencement of the operation, indicates the presence of tellurium.

The Oxides of Copper.-The action of the fluxes, &c., on these bodies has already been pointed out.

Chloride of Copper.-Alone, colours the flame blue, with greenish edges. A red pulverulent deposit forms on the charcoal around the assay; the fused matter reduces, giving a grain of copper, surrounded by slag.

With the fluxes, the chloride behaves as the oxides. Carbonate of Copper.-Alone, in the mattrass, gives water, and blackens.

On charcoal, it fuses, and behaves like oxide of copper.

1

Arseniate of Copper behaves with the fluxes in the same manner as the oxide of copper, but exhales a strong odour of arsenic, and gives, when reduced with soda, a white and brittle bead.

ORES OF LEAD.

Sulphuret of Lead, Galena.-Alone, on charcoal, does not fuse until after disengagement of sulphur; globules of lead then form on the surface, and finally, a bead of lead is obtained. By cupelling thus, the presence of silver may be ascertained. After cupellation, the boneash indicates by its colour whether the lead were pure or not; if it were, when cold the cupel would be pure yellow; copper renders it green and iron-brown, or blackish.

In the tube, galena gives off sulphur, and a white sublimate of sulphate of lead.

Oxide of Lead.-Its action with fluxes has been already shown.

Sulphate of Lead decrepitates, fuses on charcoal, in the outer flame into a transparent bead, which becomes milky by cooling. In the reducing flame it effervesces, giving a button of lead.

Carbonate of Lead behaves like oxide of lead.

Phosphate of Lead.-Alone, on charcoal, it fuses, the bead crystallizing as it cools. The crystals have large facets, and a pearly whiteness.

With the fluxes it behaves like oxide of lead.

ORES OF ZINC.

Zinc Blende, Black Jack, Sulphuret of Zinc.-Alone, decrepitates violently. Suffers no remarkable change on ignition; does not fuse, and gives off but a very slight odour of sulphurous acid, being very difficult to

roast.

On charcoal, an annular deposit of oxide of zinc is formed when heated violently in the outer flame.

Soda attacks it feebly; but the zinc is reduced in a good fire, with the deposition of oxide of zinc on the charcoal.

Carbonate of Zinc, Calamine.-Alone gives off no water, but becomes a white enamel, which behaves like oxide of zinc.

ORES OF TIN.

Oxide of Tin.-Its behaviour with fluxes has already been noticed.

ORES OF IRON.

Sulphuret of Iron, (magnetic pyrites).—Alone, undergoes no change.

In the open tube, gives sulphurous acid.

On charcoal, becomes red in the outer flame, and is changed, by roasting, into an oxide of iron.

Common Pyrites.—Alone in the mattrass, gives sulphuretted hydrogen and sulphur.

On charcoal it behaves like magnetic pyrites.

Mispickel, Arsenical pyrites.-Alone, gives first a red sublimate, which is sulphuret of arsenic, then a black; and lastly, in a strong fire, metallic arsenic sublimes. Treated on charcoal, the residue gives no arsenical odour, and behaves like magnetic pyrites.

On charcoal, mispickel gives a thick smoke of arsenic, then fusing, exhaling the odour of that metal. If the mispickel contain cobalt, it can be detected after well roasting the ore, and fusing the residue with borax or microcosmic salt; and after cooling, the glass takes the characteristic colour of cobalt.

Magnetic Oxide of Iron, and Oxide of Iron, behave as already described.

Carbonate of Oxide of Iron, heated in the mattrass, gives no water. Some species decrepitate strongly. Exposed to a gentle heat, it blackens, and gives oxide of iron, very attractable by the magnet.

Chromate of Iron.-Alone, undergoes no alteration. With borax and microcosmic salt, the solution is slow but complete. The characteristic colours are alone apparent when the bead is hot; but as soon as it cools,