sometimes, but quite so with the aid of the magnifying glass.

_Lead_, or its chloride, sublimes like tellurium, and, like that
substance, fuses into globules or drops.

_Bismuth_, or its sulphide, sublimes into an orange or brownish
globules, when it is melted, as directed above, for tellurium. The
color of the bismuth and lead oxides are somewhat similar, although
that of the latter is paler.

If any mineral containing _fluorine_, is fused, first with the
microcosmic salt bead, then put into the tube, and the flame of the
blowpipe be directed _into_ the tube upon the bead, hydrofluoric acid
is disengaged and attacks the inside of the tube. The fluoride of
calcium, or fluorspar, may be used for this experiment.

During the roasting, a brisk current of air should be allowed to pass
through the tube, whereby unoxidized matter may be prevented from
volatilization, and the clogging up of the substance under examination
be prevented.


3. EXAMINATIONS UPON CHARCOAL.


In making examinations upon charcoal, it is quite necessary that the
student should make himself familiar with the different and
characteristic appearances of the deposits upon the charcoal. In this
case I have found the advice given by Dr. Sherer to be the best; that
is, to begin with the examination of the pure materials first, until