This is prepared by dissolving a troyounce of iodine in a pint of alcohol. it is not quite saturated; and it is best, perhaps, as an officinal preparation, that it should not be so; for the least exposure would cause precipitation by the evaporation of the alcohol. Even as it is, it should be kept in a well-stopped bottle. in time, and especially on exposure to sunlight, it undergoes chemical changes, in consequence of reaction between the alcohol and iodine, and should not, therefore, be prepared in large quantities at once.

This preparation is adapted solely to topical use. it cannot be given internally without dilution; and the addition of water to it precipitates the iodine, and thus renders it liable to irritate the stomach. Even for external use, when the object is to affect the system through absorption, it is less suitable than the preparations containing iodide of potassium. As iodine cannot enter the blood unchanged, time is required for the requisite chemical reactions; whereas the iodide may be taken up immediately. Whenever, however, the object is simply to produce an impression on the surface of contact, or, by changes in the cuticle, to protect the parts beneath from the action of the air, this is the preparation to be employed.

When applied freely to the surface, it produces considerable pain and inflammation, followed usually, if the quantity applied has been considerable, by desquamation of the cuticle. The best method of applying it is by means of a camel's-hair pencil. To produce the full effect, it should be used undiluted; and it is often advisable to renew the application daily, or oftener. in contact with the mucous membranes, with the epithelium sound, it occasions little pain, unless parts are touched near the orifices of the cavities lined by the membrane, as the lips, the anal orifice, etc., in which case the application is severely painful. (Boinet, l'Union Med., Juin 14, 1856.) When used for injection into serous cavities, as in hydrocele, ovarian dropsy, empyema, etc., it should be diluted with an equal bulk, or twice its bulk of water. M. Velpeau uses the latter proportion, M. Berard the former. M. Jobert injects it, without dilution, into purulent cavities. {Trousseau et Pidoux, 4e ed., i. 225.) As an embrocation in scrofulous tumours, and other swellings and indurations, it may be diluted with from four to six parts of camphorated tincture of soap; but other preparations of iodine are preferable for this purpose.

The particular circumstances under which it is used have been, for the most part, already enumerated, or will be so hereafter under rubefacients or Protectives.

The vapour from a bottle of the tincture warmed by being held in the hand, inspired into the nostrils, has been successfully used in his own case in the treatment of coryza, by M. Luc, who thus inhaled the vapour for about an hour; the several inhalations lasting somewhat less than a minute, with an interval of three minutes between them. He has since used the remedy with equal success in others. (Ann. de Thérap., 1866, p. 235.)

Still another local application of the tincture of iodine, suggested by Dr. Luton, of Rheims, is by subcutaneous injection in diseases seated in the tissues beneath the skin, such as certain cases of neuralgia, acute or indolent disease of the lymphatic glands, scrofulous tumours, goitre, etc. The tincture, Dr. Luton says, causes a light, frank inflammation, not suppurative, and sometimes followed by atrophic absorption. (Arch. Gén., 6e sér., ii. 386.)

If given internally, the dose may be from ten to twenty drops, grad-. ually increased to thirty or forty, three times a day. it may be given in sweetened water, or wine, when not contraindicated. A good vehicle is syrup of orange-peel, diluted with water.