In syphilis, one grain may be given two or three times a day; but its action should be watched, and if it causes salivation, tenderness of the gums, and a coppery taste in the mouth, it should be discontinued until these symptoms disappear. _Camphor._—Dose, two to five grains. Is a stimulant, and an antispasmodic; it helps to calm the nervous system. It is used in cholera and in fevers, and is taken for colds in the head. Camphor is slightly soluble in water, and this solution makes a cooling lotion, which is useful for inflamed or painful parts. A lump of camphor is a good repellent for sand-flies. _Spirit of camphor_ consists of one part of camphor in ten of alcohol; the dose is ten to twenty drops. _Camphorated oil_ consists of one ounce of camphor in four ounces of olive oil, and makes a stimulating liniment for stiff and painful parts. A stronger liniment may be made by adding to this an ounce of spirit, and half to one ounce of solution of ammonia or oil of turpentine. * _Carbolic acid, or phenol._—Dose, one or two grains may be given internally, well diluted, for acute diarrhœa, dysentery, and cholera. Is mostly used as an external application. Carbolic acid acts as a caustic, and may be applied on the end of a match in the case of boils (p. 227). A drop on a piece of cotton-wool applied to a hollow tooth quickly relieves pain. It is much used as an antiseptic lotion for wounds and foul sores, and for cleansing hands and instruments before operation. One part in twenty of water makes a strong solution for cleansing instruments and disinfecting dysenteric and other stools. One part in sixty may be used for sponging or syringing sores and wounds. One part added to nineteen of olive, or other oil, makes carbolic oil, which is a handy dressing for all kinds of wounds. One part to nineteen parts of vaseline, or fresh lard, makes carbolic ointment. _Cascara sagrada, extract of._—Dose, two to six grains. Is a valuable aperient, especially in chronic constipation. Cascara tablets, two grains each, are convenient, and one or two should be taken at night. _Cathartic Co. Tablets._—A useful purge in cases of fever or liver derangement. Two or three for a dose when required. _Castor oil._—Dose, one to three tablespoonfuls. It is a good aperient, but is not very convenient for the traveller, as it takes up much space, which could be better used for aperients which are not so bulky, _e.g._, calomel or cascara. The usual dose of castor oil should be somewhat reduced in the tropics, where it is often not so well borne as in temperate climates. _Note._—The seeds of the castor oil plant should not be eaten, as they are poisonous.