_Beer_, _ale_, and _porter_ are made from an infusion of malt—that is, fermented barley, flavored with hops. They each contain from 4 to 6 per cent. of alcohol. In large doses alcohol in any form causes mental excitement, delirium, loss of co-ordination, and finally stupor and coma. Death may result from paralysis of the heart or respiration. =Aloes.=—This is cathartic and stimulant, and is given in chronic constipation, amenorrhea, and atonic dyspepsia. The laxative _dose_ is from ½ to 2 grains; the purgative and emmenagogue _dose_ is 2 to 5 grains. =Ammonia.=—This is a gas employed medicinally in the form of a watery solution (water of ammonia) or an alcoholic solution (spirit of ammonia). These preparations are used internally as heart stimulants, respiratory stimulants, gastric antacids, and externally as counterirritants. The _dose_ of the _Aromatic Spirit_ (Spiritus Ammoniæ Aromaticus) is from ½ to 1 dram (2-4 c.c.), well diluted. Large doses of ammonia preparations cause burning pain in the throat and abdomen, vomiting, purging, and collapse. =Antipyrin.=—This drug has about the same action and uses as acetanilid, and may be given in the same _dose_. =Antitoxin of Diphtheria.=—This is obtained from healthy horses which have been rendered artificially immune to diphtheria from having received a prolonged course of treatment with diphtheria toxin in doses gradually increased. The immunity is due to the formation in the blood of a substance which in some way counteracts the poison or toxin of the disease. This substance is known as the antitoxin. It exists in the serum of the blood, and so far has not been separated from it. The dose of the serum is measured in units, a unit being ten times the amount of antitoxin required to save the life of a guinea-pig which has been injected with 100 fatal doses of diphtheria toxin. Antitoxin acts both as a curative and a preventive remedy. Since its introduction the mortality of diphtheria has been reduced more than one-half. The _curative dose_ is from 2000 to 5000 units, to be repeated in from six to twelve hours, if necessary. The _prophylactic dose_ is 500 units. The protection afforded is only temporary, lasting from two to three weeks. The injections are sometimes followed by a rise of temperature, pain in the joints, or a cutaneous rash, but these symptoms are without serious significance. =Aspirin.=—This is acetyl-salicylic acid and is used like sodium salicylate in rheumatism and pleurisy, and as an antipyretic and analgesic. _Dose_, 5 to 15 grains.