=Iodids.=—The salts of iodin—potassium, sodium, ammonium iodid—resemble each other in their action and uses. They are used as alteratives in constitutional diseases, like chronic rheumatism and gout, as absorbents of exudates in chronic inflammatory diseases, and as eliminants in chronic mineral poisoning. Their continued use occasions a group of symptoms—frontal headache, nasal discharge, sore throat, and a cutaneous eruption—termed _iodism_. The _dose_ is from 5 to 30 grains (0.3-2 gm.), well diluted, after meals. =Iodoform.=—This drug owes its virtues to iodin, of which it contains about 50 per cent. When brought into contact with raw surfaces it exerts a mild anesthetic effect, liberates its iodin, and thereby acts as an antiseptic. When applied too freely it may be absorbed and cause toxic effects—headache, elevation of temperature, restlessness, a diffuse red rash on the face and limbs, delirium, stupor, and collapse. The unpleasant odor of the drug can be removed from the hands and from instruments by oil of turpentine. =Ipecac.=—This drug is used as an emetic and expectorant. As an emetic it is safe, but somewhat slow in action. It is especially useful in the young and feeble, as it causes but little depression. The _dose_ of powdered ipecac, as an emetic, is from 20 to 30 grains (1.2-2 gm.); of the _Syrup_ (Syrupus Ipecacuanhæ), as an expectorant, from 10-60 minims (0.6-4 c.c.); as an emetic, from 2 to 4 drams (8-15 c.c.); of the wine, as an expectorant, from 10 to 30 minims (0.6-1.8 c.c.); as an emetic, 1 dram (4 c.c.). =Iron. (Ferrum).=—The various preparations of iron are employed as tonics and astringents. As tonics, they are especially indicated in simple anemia; as astringents they are employed locally in bleeding, and, internally, in diarrhea. The _dose_ of _Reduced Iron_ (Ferrum Reductum) is from 1 to 5 grains (0.06-0.3 gm.); of the _Pills of Iron Carbonate_ or _Blaud’s Pills_ (Pilulæ Ferri Carbonatis), 1 to 3 pills; of the _Tincture of Ferric Chlorid_ (Tinctura Ferri Chloridi), 5 to 10 minims (0.3-0.6 c.c.); of the _Solution of Iron and Ammonium Acetate_ or _Basham’s Mixture_ (Liquor Ferri et Ammonii Acetatis), 1 to 4 drams (4-15 c.c.); of the _Sulphate of Iron_ (Ferri Sulphas), 1-3 grains (0.06-0.2 gm.); of the Syrup of _Iodid of Iron_ (Syrupus Ferri Iodidi), 5 to 60 minims (0.3-4 c.c.). The _Solution of Iron Subsulphate_ (Monsel’s solution) is used only as a hemostatic, and _Iron Hydrate with Magnesia_ as an antidote in arsenic-poisoning. The _dose_ of the latter is a tablespoonful every ten to fifteen minutes.