ion, 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 mass
gives a sulphur reaction.

(8) Special reactions. If the copper bead obtained by fusing upon
carbonate of soda be cupelled with assay lead, a
silver bead will be obtained. Or if dissolved in
nitric acid and a drop or two of HCl added, a
white precipitate of AgCl will be formed, which
may be collected and reduced with carbonate of
soda upon charcoal.

* * * * *

Mineral. Tennatite

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

Behavior

(1) in glass-bulb. Decrepitates occasionally and gives a red
sublimate of [,,,As].

(2) in open tube. Evolves [..S] and [...As], which condense and
form a white sublimate.

(3) on charcoal. Fuses to a magnetic bead giving of arsenical and
sulphurous fumes.

(4) in forceps. --

(5) in borax. As the preceding.

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

(7) with carb. soda. Yields a copper bead and metallic iron in the
form of a dark grey powder. The fused alkali
gives the sulphur reaction.

(8) Special reactions. --

* * * * *

Mineral. Bournonite

Formula. ([,Pb]^{2}[,Cu=])[,,,Sb].

Behavior

(1) in glass-bulb. Decrepitates giving off sulfur and, when
strongly heated, [,,,Sb] and [...Sb].

(2) in open tube. Evolves thick white fumes of [...Sb],[.....Sb]
and [.Pb][...Sb]. Also [.S].

(3) on charcoal. Fuses readily and incrusts the charcoal with
[...Sb] and [.Pb] leaving a dark colored bead.

(4) in forceps. --

(5) in borax. If the bead obtained on charcoal be fused on
that support in the reducing flame with borax, a