Crotonic acid, or its products, are occasionally absorbed, and cause disturbance of the heart and nervous centres.

Oleum Ricini-Castor Oil.-The oil expressed from the seeds of Ricinus communis. Imported chiefly from Calcutta.

Characters of the seeds.-Oval, somewhat compressed, smooth and shining, grey, marbled with reddish-brown or blackish-brown spots and stripes.

Substance resembling Castor Oil Seed: Croton Oil Seed (q.v.).

Characters of the oil.-Viscid, colourless, or pale straw yellow, having a slightly nauseous odour and a somewhat acrid taste. Entirely soluble in one volume of alcohol and in two volumes of rectified spirit.

Composition.-The bulk of castor oil consists of ricinoleic acid, C18H34O3, combined with glycerine. Palmitin, stearin, cholesterin, and possibly a resin and an alkaloid also occur in small quantities.

Dose.-1 to 8 fl.dr.

Preparations.

Oleum Ricini is contained in: Collodium Flexile (1 in 49), Linimentum Sinapis Compositum (1 in 9), and Pilula Hy-drargyri Subchloridi Composita (1 in 5).

Action And Uses. 1. Immediate Local Action And Uses

Externally, pure castor oil is bland, like almond oil; and is applied as a local sedative and protective, for instance, in injury of the conjunctiva by quicklime.

Internally.-Castor oil is perfectly non-irritant if pure, until it reaches the duodenum, where it is decomposed by the pancreatic juice, and the ricinoleic acid at once comes into action. If the oil be rancid, irritation of the stomach will cause nausea and vomiting.

Castor oil is a simple purgative, at once rapid and certain, mild and painless, producing one or more liquid but not watery stools in four to six hours, followed by a sedative effect. It is believed to stimulate the muscular coat and intestinal glands, but not the liver. It also purges when given as enema.

Castor oil is used as the best of all simple purgatives when a free evacuation of the bowels only is desired. It can be given in all conditions where a laxative is permissible, and is therefore specially employed in the treatment of diarrhoea due to the presence of indigestible or undigested food in the bowels, in the constipation of typhoid fever, after abdominal operations, in pregnancy, and post-partum. It is a valuable purgative for children and for the old and infirm. In some forms of indigestion in infants, and of chronic obstruction of the bowels, small doses (5 min. for an infant), may be given three or four times a day for days or even weeks, as an emulsion, with the best result. Small doses of tincture of opium are sometimes combined with castor oil.

2. Action On The Blood ; Specific, And Remote Local Action

Ricinoleic acid enters the blood and tissues, and leaves the body in the excretions, including the milk, which purges the infant at the breast.

The Leaves of the Castor Oil Tree, applied locally to the mamma as a poultice, are said to be galactagogue.

Kamala-Kamala.-A powder which consists of the minute glands that cover the capsules of Rottlera tinctoria. Imported from India.

Characters.-A fine granular mobile brick-red powder, with little odour or taste ; difficult to mix with water ; mainly soluble in alcohol and ether, the residue consisting principally of tufted hairs.

Impurities.-Sand or earth. Resembles Oxide and Iodide of Mercury, but is not heavy.

Composition.-Kamala contains an active resin, rottlerin, allied to coussin (see Cusso), tannin, red colouring matter, etc.

Dose.-30 gr. to 1/4 oz., as an electuary with tamarinds.

Action And Uses

Kamala is an anthelmintic and slight gastro-intestinal irritant, sometimes causing nausea, vomiting, colic, and diarrhoea. It is used to expel the tape-worm, lumhricoid, and oxyuris.