should be kept in a glass of water. To use them, we dip the wetted
hooked end into the powdered flux (borax or microcosmic salt) some of
which will adhere, when we fuse it in the flame of the blowpipe to a
bead. This bead hanging in the hook, must be clear and colorless.
Should there not adhere a sufficient quantity of the flux in the first
trial to form a bead sufficiently large, the hook must be dipped a
second time in the flux and again submitted to the blowpipe flame. To
fix the substance to be examined to the bead, it is necessary, while
the latter is hot, to dip it in the powdered substance. If the hook is
cold, we moisten the powder a little, and then dip the hook into it,
and then expose it to the oxidation flame, by keeping it exposed to a
regular blast until the substance and the flux are fused together, and
no further alteration is produced by the flame.

The platinum wire can be used except where reduction to the metallic
state is required. Every reduction and oxidation experiment, if the
results are to be known by the color of the fluxes, should be effected
upon platinum wire. At the termination of the experiment or
investigation, if it be one, to, clean the wire, place it in water,
which will dissolve the bead.

(_d._) _Platinum Foil._--For the heating or fusing of a substance,
whereby its reduction would be avoided, we use platinum foil as a
support. This foil should be of the thickness of good writing paper,
and from two and a half to three inches long, by about half an inch
broad, and as even and smooth as possible. If it should become injured
by long use, cut the injured end off, and if it should prove too short
to be held with the fingers, a pair of forceps may be used to grasp
it, or it may be placed on a piece of charcoal.