Evidence may be found both for and against the use of mercurial ointment (ung. hydrarg.) in these conditions (Stille). The application cannot be depended on for the arrest of erysipelas, but it has some power to relieve the burning pain, and to lessen the chances of pitting in small-pox: it certainly can prevent the maturation of a vaccine vesicle. The late Dr. Hughes Bennett thought highly of this treatment, and Mr. J. F. Marson says that a mercurial plaster in use at the Children's Hospital, in Paris, answers well: it is a modification of the emplastrum Vigo c. mercurio, and contains 25 parts mercurial ointment with 10 of yellow wax and 6 of black pitch; it is most suitable for semi-confluent cases, where the patient can use a little care, for in severely confluent attacks the application would soon be rubbed off by the restless movements ("Reynolds' System," vol. i.). There is also some risk of salivation, and other forms of ointment answer equally well, so that, although I have tried mercurial preparations in such cases, I have latterly abandoned their use.