precipitate be separated after boiling, or so small a quantity as cannot
well be collected,—evaporate the liquid to dryness, char it by means of
nitric acid and chlorate of potash, as directed for copper (p. 357),
boil the carbonaceous mass for half an hour in a mixture of eight parts
of hydrochloric acid and one of nitric acid, and introduce the filtered
solution into the modification of Marsh’s apparatus for detecting
arsenic described in page 204, but without the tube _e h_. Kindle the
gas at _e_, and try whether a black, dull stain, not removable by
solution of chloride of lime, be produced on a surface of porcelain held
across the flame. If no stain be produced, there was no antimony in the
liquid under examination. If the porcelain be stained, apply the heat of
a spirit-lamp flame to the tube _d e_. Antimony will be deposited within
the tube where the heat is applied. In order to ascertain its nature,
break the tube, heat the portion containing the crust with
nitro-hydrochloric acid, evaporate to dryness, dissolve the residue in
hydrochloric acid, decompose a part of this solution with water, and
subject the rest to a stream of hydrosulphuric acid gas, which will
produce the usual orange sulphuret of antimony.