Figure 8-21.—Field identification of unknown bituminous materials.
Field
identification
of
bituminous
materials is summarized in figure 8-21.
Solubility Test
The
solubility
test
consists
of
taking a small amount of the unknown
bituminous material, enough to cover the
head of a nail if a solid, or few drops of
a
liquid
material
and
attempting
to
dissolve the material by stirring it in a
petroleum
distillate;
gasoline,
kerosene,
diesel fuel, and so forth. If the material
is an asphalt, it will mix uniformly with
the distillate. Tars, however, will form a
stringy
undissolved
mass.
Emulsions,
in
addition
to
other
distinguishing
tests,
may also be identified in the solubility
test
since
they
will
form
undissolved
balls or beads of the emulsion at the
bottom
of
the
container
of
petroleum
distillate.
The
solubility
test
provides
a
positive method of identification (fig. 8-
22).
8-24
