80 MATERIA MEDICA. 



diet in dyspepsia and constipation ; believed to produce its laxative 

 impression by mechanical irritation ; best used in the form of bra?i- 

 bread, made from the unbolted flour. 



Purging Cassia. — (Cassia Fistula, U. S.) 



Fruit of the C. fistula, a tree growing in the East and West 

 Indies; consists of pods about a foot in length, containing numerous 

 seeds surrounded with a black, sweetish pulp. The pulp is pro- 

 cured by bruising the pods, and boiling in water. It is a mild laxa- 

 tive, and forms one of the ingredients in the Confection of Senna. 

 Dose 3j to 3j. 



Manna, U. S. 



Concrete juice of the Ornus Europcsa, a tree growing in the 

 countries bordering the Levant. Procured both by spontaneous ex- 

 udation, and incisions. Three varieties found in commerce. 1. 

 Flake Manna, the result of spontaneous exudation ; comes in pieces 

 two or three inches long, about an inch wide, bearing the marks of 

 the bark, &c., on which it has concreted ; colour, yellowish- 

 white ; odour, faint; taste, sweetish. 2. Common Ma7i7ia, pro- 

 cured, when the season is more advanced, by incisions ; consists of 

 particles of the flake, mixed with a fluid portion and impurities; 

 colour, darker; inferior. 3. Fat Manna, obtained still later in the 

 season ; consists chiefly of the fluid portion, with numerous impuri- 

 ties ; colour, much darker. Manna consists of common sugar, 

 united to a peculiar saccharine principle, called mannit.e. 



Uses. — A mild laxative, adapted to cases of constipation, hsemor- 

 rhoids, and pregnancy ; also to children. Dose, 5j to 5ij. 



Castor Oil. — (Oleum Ricini, U. S.) 



Product of the Ricinus communis, or Palma Christi, growing in 

 various parts of the world. As found in the United States, it is an 

 annual. The fruit is a three-celled capsule, each cell containing an 

 oblong, spotted, brownish seed. The seeds are powerfully purga- 

 tive, in consequence of an acrid principle which they contain, and 

 which is dissipated by a high heat. The oil is procured either by 

 expression or decoction. 1. Expression. The seeds are gently 

 heated, and then subjected to powerful pressure ; a thick, whitish 

 oil exudes, which is boiled for some time in a large quantity of 

 water; this dissolves out the mucilage, and coagulates the albumen; 

 the clean oil is now removed, and boiled with a minute quantity of 

 water, to drive off the acrid principle. 2. Decoction. The seeds are 

 bruised and boiled in water ; the oil rises and is skimmed off the 

 surface, and is again boiled to remove the acrid principle ; apt to 

 have a darker colour than the other. The acrid principle is thought 

 to consist of several acids. 



