Infusion is perhaps the most frequent form in which senna is exhibited. This may be prepared in the proportion of a troyounce of senna, with one or two drachms of fennel-seed, cardamom, or coriander,to a pint of boiling water; though, in consequence of the tendency to precipitation on being kept, it is best to prepare only one-half the quantity at one time. The dose is about four fluidounces. But it is almost always best to use one of the saline cathartics together with the senna and the aromatic; and the addition of manna, while it adds to the cathartic property, answers a good purpose by correcting the taste. The following is an excellent formula.

A compound infusion of senna may be made by taking of senna half an ounce, of sulphate of magnesia and flake manna, each, an ounce, of fennel-seed a drachm, and of boiling water half a pint, and macerating in a covered vessel till the infusion becomes cool. One-third, or one-half of this quantity, may be given for full purgative effect, repeated, if necessary, in from four to six hours; or, in cases of somewhat irritable stomach, one or two fluidounces may be taken every hour or two till it operates.

There are two tinctures of senna, both of which are forms of the old elixir salutis; namely, the Tincture of Senna and Jalap (Tinctura Sennae et Jalapae) of the U. S. Pharmacopoeia of 1850, made of the two ingredients mentioned in the title, with the addition of cardamom; and a Compound Tincture of Senna (Tinctura Sennae, Br.; Tinctura Sennae Composita, Lond., Dub.), containing various aromatics, with raisins, besides senna. in the dose of from two fluidrachms to a fluidounce, either of these tinctures may be used as an adjuvant to purgative infusions, to render them more stimulating in a debilitated state of the stomach, or as a cathartic, without addition, in persons habituated to the use of alcoholic drinks. Neither is now recognized in our national code.

Syrup of Senna (Syrupus Sennae, Br.) is made, according to the directions of the British Pharmacopoeia, by adding sugar to a strong infusion of senna, previously mixed with oil of coriander and a little alcohol, the former to improve its flavour and correct its griping property, the latter to contribute to its preservation. The preparation has been discarded from the U. S. Pharmacopeia, probably because superseded by the fluid extract of senna and fennel-seed. The London and Edinburgh Colleges formerly prepared the syrup by first making a very strong infusion, and incorporating this with molasses, which had been previously boiled to evaporate the moisture, and was added to the infusion while still boiling hot. The latter syrup had the advantage, that the taste of the senna was concealed by that of the molasses. it was generally employed for children, in the dose of one or two fluidrachms.

Fluid Extract of Senna (Extractum Sennae Fluidum, U. S.) is peculiar to our Pharmacopoeia. it is prepared by evaporating a tincture of senna sufficiently by means of the water-bath, and then incorporating it with sugar. Formerly Hoffmann's anodyne and oil of fennel were added; the former to aid in its preparation, the latter as a carminative. in the present code, it is thought best to leave to the prescriber the choice of the aromatic oil, two minims of which may be added to each fluidounce. The ethereal addition is not considered essential, for the purpose intended. The fluid extract is an efficient preparation, if well made. The dose is half a fluidounce for an adult, and half a fluidrachm for a child a year or two old.

Subordinate to senna, as belonging to the same genus of plants, and having the same character, though somewhat weaker, the following cathartic may be suitably considered in this place.