At the request of Prof. Torald Sollmann of the Council on Pharmacy and Chemistry of the American Medical Association, we made a comparative study of several oily preparations of red mercuric iodid for intramuscular injections in syphilis. The information, concerning the preparations submitted to the investigators, was as follows: OILY SOLUTION OF RED MERCURIC IODID “It is desired to ascertain whether there is any difference between three preparations, each containing 1 per cent. of mercuric iodid, as to pain, discomfort, induration, etc. The preparations will be labeled “1,” “2” and “3.” They will be sterile. “One of these preparations will be a plain solution in oil; another will contain, in addition, 2.5 per cent. of guaiacol; the third will be a proprietary preparation containing the guaiacol. “It is also desirable to know how the oily solution compares with the plain watery solution; but this is of secondary importance.” The preparations all had the same appearance. The patients were taken indiscriminately, and we attempted to keep them on the injections as long as possible, in order to compare symptoms. Owing, however, to discharge from hospital, symptoms of mercury intoxication, etc., we were unable in all cases to give a thorough trial with each preparation. In all, eleven patients were treated and seventy-one injections given--by which time our experimental supply was exhausted. In each case the drug was given intramuscularly in the buttocks and the patients carefully observed for subjective symptoms of pain and for objective symptoms of swelling, induration, abscess formation, etc. The details are given in Table 1. As will be noted, in several of the cases the patients were more or less confused and gave rather indefinite and conflicting answers. In attempting to compare the results from the different drugs, by careful tabulation one finds that symptoms were more marked with the respective sample as follows: Preparation 1 was worse than Preparation 2 or 3 in six cases. Preparation 2 was worse than Preparation 1 in two cases. Preparation 2 was worse than Preparation 3 in five cases. Preparation 3 was worse than Preparations 2 or 1 in one case.