must be subjected again to the
same process. By examining the bead, both when hot and cold, by
holding it up against the light, it can be soon ascertained whether it
is free from dirt by the transparency, or the want of it, of the bead.

In order to make the examination of a substance, the bead should be
melted and pressed against it, when enough will adhere to answer the
purpose. This powder should then be fused in the oxidation flame until
it mixes with, and is thoroughly dissolved by the borax bead.

The principal objects to be determined now are: the color of the borax
bead, both when heated and when cooled; also the rapidity with which
the substance dissolves in the bead, and if any gas is eliminated.

If the color of the bead is the object desired, the quantity of the
substance employed must be very small, else the bead will be so deeply
colored, as in some cases to appear almost opaque, as, for instance,
in that of cobalt. Should this be the case, then, while the bead is
still red hot, it should be pressed flat with the forceps; or it may,
while soft, be pulled out to a thin thread, whereby the color can be
distinctly discovered.

Some bodies, when heated in the borax bead, present a clear bead both
while hot and cold; but if the bead be heated with the intermittent
flame, or in the flame of reduction, it becomes opalescent, opaque or
milk-white. The alkaline earths are instances of this kind of
reaction, also glucina oxide of cerium, tantalic and titanic acids,
yttria and zirconia. But if a small portion of silica should be
present, then the bead becomes clear. This is likewise the case with
some silicates, provided there be not too large a quantity present,
that is: over the quantity necessary to saturate the borax, for, in
that case, the bead will be opaque when cool.

If the bead be heated on charcoal, a small tube or cavity must be
scooped out of the charcoal, the bead placed in it, and the flame of
reduction played upon it. When the bead is perfectly fused, it is
taken up between the platinum forceps and pressed flat, so that the
color may be the more readily discerned. This quick cooling also
prevents the protoxides, if there be any present, from passing into a
higher degree of oxidation.

The bead should first be submitted to the oxidation flame, and any
reaction carefully observed. Then the bead should be submitted to the
flame of reduction. It must be observed that the platinum forceps
should not