The _hypodermic use of mercury_ can be made effective, but there are but few preparations which can be used that do not cause pain and subsequent irritation. Perhaps that which gives least pain is the sozoiodolate of mercury. This is sparingly soluble in water, dissolving in about 500 parts by weight. As the dose is 9 or 10 Cg., the amount of water necessary for this solution is so bulky that the dose should be injected into the gluteal region. Corrosive sublimate is also used in 1 per cent. solution, made up in common salt solution of the usual strength of 9 to 1000. Of this 10 minims represent a suitable dose to commence with, which may be increased to 30 or 40 minims when necessary. This should be given in the same region, the needle being driven in its full length perpendicularly to the surface. When this is done an injection is made into the muscle, where it seems to be more effective than in the subcutaneous fat. When the dose is increased to more than 20 minims a 2 per cent. solution may be used and the amount of fluid correspondingly reduced. _Fumigation_ is a method now not often adopted, calomel being used for the purpose, an ordinary cabinet hot-air bath confining the vapor about the patient. One treatment a day by either of these methods is usually sufficient. About the _initial sore_ dry calomel, pure or reduced with bismuth subnitrate, may be used. The condylomas met with about the perineum will often shrink and disappear under the influence of this application. _Mucous patches_ should be treated with absolute cleanliness; in the mouth a wash of diluted hydrogen dioxide may be used, and the patches touched with a strong nitrate of silver solution, pure carbolic acid, or camphophenol. This will not prevent contagion from such a source, but will reduce it to a minimum beneficial in every respect. The various eruptions of syphilis will disappear gradually under the influence of a local application of one of the mercurial preparations, either the ordinary mercurial ointment or ammoniated mercury. In cases of _inherited syphilis_, especially in young children, a reduced mercurial ointment, or the use of gray powder (mercury with chalk) will give the best results. The dose should be regulated by the age of the patient; for instance, of the latter 1 to 2 Cg. for an infant. The iodides have also proved successful. _Iodine_ and its preparations have by many authorities been held to be useful in the later and especially in the gummatous lesions of syphilis. There are patients who cannot take iodine to any extent without suffering from such disturbance of mucous membranes, especially in the nose and intestines, as to make it an exceedingly unpleasant remedy.