_Phenacetin._—Dose, three to eight grains. Phenacetin is used for headaches, or for reducing the temperature in malaria and other febrile diseases, and to cause sweating. As it is very insoluble, it is best taken in the form of a powder, or in alcohol and hot water. _Potassium, bromide of. See_ Bromides. * _Potassium permanganate_ in solid form is a mild caustic, and is the active principle of Condy’s fluid, which contains about eight grains of the drug in one ounce. It is disinfectant, deodorant, and antiseptic. One part of this drug is soluble in about twenty parts of water. One grain gives a purple colour to a gallon of water. Impure water turns the purple rapidly to a brown colour, therefore the permanganate is a rough test for the presence of organic matter in water. A pale purple solution is useful as a gargle or mouth wash, also as an injection in gonorrhœa; wounds may be cleansed with a similar solution. It is especially useful in poisoned wounds, such as snake-bites, and should in these cases be injected hypodermically (p. 281). Is an antidote to poisoning by opium. Of late years it has been extensively used in the treatment and prevention of cholera. The two-grain tablet is a convenient form for medication. _Purgatives_ may be divided into the following classes:— 1. Laxatives. 2. Simple purgatives. 3. Drastic purgatives or cathartics. 4. Saline purges. 1. Laxatives slightly stimulate the movements of the bowel, but cause practically no increase of the intestinal secretion. Examples of this class are fruit, wholemeal bread, small doses of castor oil, figs, prunes, etc. These may be given regularly in slight cases of chronic constipation. 2. Simple purges are more powerful than laxatives, and in addition to stimulating the movements of the bowel increase the secretion. The result is a soft, easy motion. Examples: rhubarb, senna, cascara sagrada. 3. Drastic purgatives or cathartics. The drugs cause a profuse flow of the intestinal secretions, and, occasionally, of the bile, with greatly increased bowel movements. They cause a copious watery evacuation, accompanied by a good deal of griping. Examples: calomel, colocynth, aloes, podophyllin, croton oil, jalap and oil of turpentine; of these, podophyllin and aloes cause an increase in the flow of bile, with increased intestinal movements, so they may be said to act directly upon the liver. The result is a profuse, watery, bile-stained motion. Calomel does not act directly upon the liver, but stimulates the upper part of the bowel, so that its contents are hurried along before the bile can be reabsorbed, and a loose, watery, bile-stained motion ensues. The most useful purgative of this class is the pill containing colocynth, calomel, and hyoscyamus, of which five to ten grains should be given when there is a furred tongue, constipation, heaviness or weight over the liver, and dyspepsia and loss of appetite.