SEN NA is prepared from several species of Cassia [Casset, in NAT. HIST. DIV.], of which the aetarfolia grown in Egypt, Sennaar, and Abyssinia, and shipped from Alexandria, is considered the best. The leaflets, leaf stalks, and pods are frequently present in the senna used in medicine. The pulp of C. Fistula, called also Catliartoearpv-s Fiatuto, consists chiefly of sugar and gum, with some other principles, and is a mild laxative. It accordingly enters into the composition of tho con fection of cassia, and the confection of senna or lenitive eleetuary. These are pleasant-tasted but rather bulky purgatives for children. They are not much used, and the pulp of cassia is chiefly employed to form what is termed essence of coffee. This, when prepared from pulp which has not been kept too long, is mildly cathartic, and a very proper article of diet for persons subject to habitual constipation.
Senna contains a peculiar principle called eathartine, with a fat oil, and a little volatile oil, a colouring principle, mucilage, and malate and tartrate of lime, ehlorophylle, &c.
The active or purging principle is yielded to water, both cold and warm, and to alcohol. If the infusion be made with cold water, it never gripes : this method is now much employed to form the con centrated infusions supplied by wholesale chemists and druggists to country practitioners. It requires that the water should stand twenty four hours on the leaves, which should be kept down with a heavy weight, and the air excluded as thoroughly as possible. The tincture is almost an unnecessary form, while the powder is objectionable from its bulk and disagreeable taste. Various articles, especially aromatics, are occasionally added to infusions to correct its griping tendencies, or increase its purgative power. The confection is an example of such combinations in a solid state. A carefully prepared extract keeps well, retains the odour and virtue for years, and may be given in moderate sized boluses or pills.