on.

Manganese oxides fuse with borax in the oxidation flame to a clear and
intensely colored bead, of a violet hue while hot, but changing to red
as it cools. If a considerable quantity of the oxide is added, the
bead acquires a color so dark as to become opaque. If such be the
case, we have to press it flat, by which its proper color will become
manifest.

In the reduction flame the bead is colorless. A very dark colored bead
must be fused upon charcoal with the addition of some tin. The bead
must be cooled very suddenly, for if it cools too slowly, it then has
time to oxidize again. This may be effected by pushing it off the
platinum wire, or the charcoal, and pressing it flat with the forceps.

The oxides of manganese fuse with microcosmic salt in the oxidation
flame, to a clear brownish-violet bead, which appears reddish-violet
while cooling. This bead does not become opaque when overcharged with
manganese. As long as it is kept in fusion a continued boiling or
effervescence takes place, produced by the expulsion of oxygen, in
consequence of the fact that the microcosmic salt cannot dissolve much
sesquioxide, while the rest is reduced to protoxide, is re-oxidated,
and instantly again reduced. If the manganese is present in such a
minute quantity as not to perceptibly tinge the bead, the color may be
made to appear by the contact of a crystal of nitre while hot. The
bead foams up upon the addition of the nitre, and the foam appears,
after cooling, of a rose-red or violet color. In the reduction flame
the bead sometimes becomes colorless.

The oxides of manganese fuse with carbonate of soda upon platinum
foil or wire, to a clear green bead, which appears bluish-green and
partially opaque when cold (manganate of soda NaO + MnO^{3}). A very
minute trace of manganese will produce this green color. The oxides of
manganese cannot be reduced upon charcoal with carbonate of soda
before the blowpipe. The soda is absorbed, and (MnO + Mn^{2}O^{3}) is
left.

GROUP FIFTH.--IRON, COBALT, NICKEL.

The oxides of this group are reduced to the metallic state when fused
with carbonate of soda upon charcoal in the reduction flame. Metals
when thus reduced form powders, are not fusible or volatile in the
blowpipe flame, but they are attracted by the magnet.

Furthermore, these oxides are not dissolved by carbonate of soda in
the oxidation flame, but they produce colored beads with borax and
microcosmic salt.

(_a._) _Iron._