other mineral acids, for it does not form any insoluble salt or
precipitate with bases.
The most convenient process consists in first ascertaining the acidity
of the fluid, then neutralizing it with potass, evaporating to dryness,
and heating the residue in a tube with sulphuric acid. The vapour
disengaged, if abundant, may be known by its orange colour in the tube
and its odour. But if small in quantity it is best to distil over the
vapour in a proper apparatus, and to subject the condensed product to
the tests of morphia, narcotin dissolved in sulphuric acid, and
proto-sulphate of iron dissolved in water. A convenient tube for the
purpose is that represented in Fig. 3; into which the materials are
introduced by the funnel, Fig. 4. The wide part of the tube may then be
drawn out in the spirit-lamp flame to any length or fineness that may be
necessary, so as to conduct the vapour into another tube as a condenser,
or directly into the substances to be used as tests.