(Hæmatoxylon Campechianum). _Logwood._
QUALITIES. The wood is hard, compact, and heavy. _Odour_, none; _Taste_,
sweet, and astringent; _Colour_, deep red. CHEMICAL COMPOSITION. The
colouring matter of this wood has been very recently submitted to a
rigid examination; and the name of _Hematin_ has been given to it; it
affords small brilliant crystals of a reddish white colour, and slightly
astringent, bitter, and acrid flavour; sulphuretted hydrogen passed
through its solution in water, gives it a yellow colour, which
disappears in a few days. Gelatine throws it down in reddish flakes. The
habitudes of Logwood are curious with respect to mutability of colour.
The recent infusion, made with distilled water, is yellow, but that with
common water has a reddish purple colour, which is deepened by the
alkalies, and changed to yellow by the acids; various salts precipitate
it; _acetate of lead_; _alum_; the _sulphates of copper and iron_;
_tartarized antimony_; and _sulphuric_, _muriatic_, _nitric_, and
_acetic acids_, are on this account incompatible with it. MED. USES. It
is supposed to be astringent, and is therefore given in protracted
diarrhœas, and in the latter stage of dysentery. OFFICINAL PREP.
_Extract. Hæmatoxyli._ L.