throw down any lead which may remain in solution. It is then to be
filtered while _cold_, and evaporated sufficiently in a vapour-bath. The
solution in this state will sometimes be sufficiently pure for the
application of the tests for morphia; but in most cases it is necessary,
and in all advisable, to purify it still farther. For this purpose the
morphia is to be precipitated with carbonate of soda; and the
precipitate having been collected, washed, and drained on a filter, the
precipitate and portion of the filter to which it adheres are to be
boiled in a little pure alcohol. The alcoholic solution,—filtered, if
necessary,—will give by evaporation a crystalline residue of morphia,
which becomes orange-red with nitric acid, and blue with perchloride of
iron. The latter property I have sometimes been unable to develope when
the former was presented characteristically.