These are preparations for injection into the rectum. When the quantity injected is large, and especially if cold, it is usually returned almost immediately; therefore, when we wish to get it retained, a small quantity only, and warm, must be employed. The vehicle in most injections is starch mucilage. In the enema of aloes 10 ounces, and in those of Epsom salts and of turpentine, 15 ounces of the vehicle are used, and these enemata are employed for the purpose of evacuating the bowel. In the case of the enema opii which we wish to be retained the quantity is only 2 ounces. This is used both as a local and general sedative, in order to relieve pain in or about the pelvis, or to produce the general action of opium after its absorption, in cases where medicines cannot be retained by the stomach, or when it is un-advisable to administer them by the mouth. The enema asafoe-tidae is perhaps the most powerful remedy we possess in cases of tympanitic distension of the bowels. As it is used for the purpose of exciting the contraction of the bowels and the expulsion of flatulence, but not of simply evacuating the rectum, an intermediate quantity is used, viz. 4 ounces. Asafoetida contains a gum as well as a resin, and therefore no mucilage is required to suspend it, and water only is required in preparing it. The enema of tobacco is now so rarely used, on account of the danger from collapse, that it has been omitted from the B.P. of 1885; but formerly, before the introduction of chloroform, it was frequently employed in order to cause muscular relaxation of voluntary and involuntary muscles in hernia, tetanus, obstruction of the bowels, etc.

B.P. (5). None In U.S.P

Enema Aloes (aloes 40 grains, potassium carbonate 15 grains). „ Asafoetidse (asafoetida 30 gr., water 4 fl. oz.).

„ Magnesii Sulphatis (sulphate of magnesium 1 oz., olive oil 1 fl. oz.). „ Opii (tincture of opium 1/2 fl. dr.). „ Terebinthinae (oil of turpentine 1 fl. oz.).