acid gas, and if it be perceptibly coloured orange-red, treat the whole
liquid in the same way; boil to expel the excess of gas, collect the
precipitate, dry it, and reduce it by hydrogen gas in the following
manner. Put the sulphuret in a little horizontal tube, transmit hydrogen
through the tube by means of the apparatus represented in Figure 9, and
when all the air of the apparatus is expelled, apply heat to the
sulphuret with a spirit-lamp. Hydrosulphuric acid gas is evolved, and
metallic antimony is left, if the current of hydrogen be gentle, or it
is sublimed if the current be rapid.—When there is much animal or
vegetable matter present in the sulphuret, the metal is not always
distinctly visible. In that case, dissolve the antimony by the action of
nitric acid on the mixed material and broken fragments of the tube, and
throw down the orange sulphuret again from the neutralized solution by
hydrosulphuric acid.