EXTERNAL APPLICATION.—The tinct ure of iodine is extensively used as a counter-irritant. As such it may be said to have become a household remedy, and to be more or less beneficial in almost all ailments characterized by pain, except when abrasions arc present. When ap plied over the skin, the latter becomes yellow and future applications gradually cause it to become brown. Burning and itching are then experienced; the appli cations had better be stopped until the distressing symptoms disappear. As al ready stated, poisoning can occur when too great an area is covered. As a rule, the surface covered should not exceed that represented by the two hands. When applied over the chest, its effects may be sustained by painting the front of the thorax one day and the back the next. A piece of cotton wadding placed over the surfaces thus treated enhances the efficacy of the iodine. In ophthalmology it is frequently employed in the treat ment of trachoma.
Eymonnet has prepared a paper moist ened with solution of potassium iodide and dried, and another paper prepared with potassium iodide and tartaric acid, moistened and dried. If these papers be kept separate and dry they will keep in definitely. If a rubefacient be required, the papers are moistened and brought in contact with the skin. Iodine is liber ated and causes a reddening of the skin, followed by desquamation. R. Lepine (La Semaine Mad., Jan. 30, '89).
The following method of employing iodine topically is of service. A piece of
gutta-percha tissue is taken and given three or more coatings of tincture of iodine; it is then dried and applied in the selected locality, with the iodine coating turned toward the skin, and secured with a roller bandage. In this way the good results of the topical ap plication of iodine may be secured with out smarting. M. Iversen (Med. News, Apr. 20, '95).
Iodine applied by painting is absorbed by the skin. This absorption, very small when the painted part is exposed to the air, becomes much more active when it is hermetically covered. The superficial alteration of the epidermis produced by the tincture of iodine, provided it does not go on to destruction of the corneous layer, appears to be an obstacle rather than an aid to absorption. Under the most favorable conditions the absorption is too irregular to make the paintings of iodine useful in general iodine medica tion. Iodoform and ethyl-iodide are ab sorbed by the healthy skin, the latter in sufficient quantity to be useful, if needful, for a general iodine treatment. Linossier and Lannois (Bull. Gen. de Then, De liv., p. 335, '97).
Seventy-eight cases out of 100 cured with nascent iodine generated by admin istering potassium iodide internally, and, when the iodine begins to be eliminated in the lacrym al secretions, painting the upturned lid with oxygenated water. R. Roselli (Semaine Med., July 20, '93).