_Senna Leaves._
QUALITIES. _Odour_, faint and sickly; _Taste_, slightly bitter,
sweetish, and nauseous. CHEMICAL COMPOSITION. Extractive, resin,
mucilage, and saline matter; it contains within itself a purgative
principle and a bitter element; and although the latter is _per se_
inert, yet in combination, its presence aids and exalts the efficacy of
the former. M. M. Lassaigne and Fenuelle have lately announced the fact
of their having procured the purgative principle of Senna in a separate
form, and to which they have given the name of _Cathartine_. It is said
to be an uncrystallizable substance, of a reddish-yellow colour, and of
a particular smell, and bitter nauseous taste, soluble in alcohol and
water, in all proportions; but farther experiments are required upon
this subject. SOLUBILITY. Both water and spirit extract the virtues of
Senna; to water and proof spirit the leaves communicate a brownish
colour, more or less deep according to the proportions employed; to
rectified spirit they impart a fine green colour. The powdered leaves of
senna are very apt to undergo a change by exposure to a humid
atmosphere, becoming covered with a kind of mouldiness which contains a
small proportion of potass. MEDICINAL USES. See _Infus: Sennæ_.
OFFICINAL PREPARATIONS. _Confectio Sennæ_;, L.E.D. _Extract: Cassiæ
Sennæ. E. Infus: Sennæ._ L.D. _Infus: Tamarind: cum Senna._ E.D. _Pulv.
Sennæ comp:_ L. _Tinct: Sennæ._ L.D. _Tinct: Sennæ comp:_ E. _Syrup:
Sennæ._ L.D. ADULTERATIONS. The leaves of Senna are imported from
Alexandria in a state of adulteration, being mixed by the merchants of
Cairo with the leaves of _Cynanchum Oleafolium_, (Arguel) and with those
of _Colutea Arborescens_; the former are distinguished by their greater
length as well as by their structure, which differs from the leaves of
Senna in having a straight side, and being regular at their base, and in
not displaying any lateral nerves on the under disk; the latter are so
different from Senna leaves, that there is no difficulty in at once
recognising them. The _Tripoli Senna_ contains a much larger proportion
of _Cynanchum_, and of the other adulterations; as a general rule, those
leaves which appear bright, fresh, free from stalks and spots, that are
well and strongly scented, smooth and soft to the touch, thoroughly dry,
sharp pointed, bitterish, and somewhat nauseous, are to be preferred.