These recent additions to our materia medica are closely allied chemically, both being products in the distillation of coal tar.
They are of use from their faculty of coloring abraded surfaces of the cornea, thus enabling us to locate such abrasions rapidly and accurately. To the oculist this is of but little assistance, as he can readily diagnose these conditions by the methods now in use, and yet in some cases it is of assistance even to him, as in the extraction of small foreign bodies where we must get the substance between us and the iris, or against the black pupil. In these cases, the green ringaround the offending material enables us to see it in any position. Likewise, in cases where we have much photophobia, we can tell more quickly and easily to what extent the cornea is involved.
In no other condition than that of abrasion of