Prior to each injection, a patient should have a complete uranalysis, receive a cathartic on the evening preceding, and be allowed only liquids for the meal preceding. Subsequently to the injection, he should be allowed only liquids for the succeeding meal, and be retained under observation for at least twelve hours. Untoward symptoms following the injection are treated usually with epinephrin solution (0.6 to 1.2 cc.) or atropin. Arsphenamines are administered intravenously, usually in the median cephalic or the median basilic vein at the bend of the elbow. This method requires aseptic technic throughout. All apparatus should be thoroughly washed before sterilization, since it is believed that symptoms may arise from substances extracted from glassware and rubber tubing. The water used must be distilled, preferably twice, and freshly boiled. The dose of arsphenamine is 0.3 to 0.6 gm., that of neo-arsphenamine is 0.3 to 0.9 gm. Until tolerance is ascertained, the dose should be small and not repeated in less than a week. NEO-ARSPHENAMINE 1. Only a single ampule should be dissolved at a time. The powder should be dusted over the surface of a small portion of the water and permitted to dissolve without agitation. The solution is then made up to bulk. Specimens which do not dissolve readily are to be rejected. 2. Cold water only is to be used. 3. The solution should not be stronger than 0.1 gm. of the drug in 2 cc. of water. 4. A very small needle should be used, and the time of the injection should not be less than five minutes. ARSPHENAMINE 1. _Cold Water Should be Used in all Cases._—(Exception. “Arsenobenzol” requires hot water. Consult instructions issued by individual manufacturers for possible departures from these directions.) 2. _Neutralization and Alkalinization of the Solution._—With a graduated pipette or burette add 0.9 cc. of normal NaOH, standardized against normal acid, for each 0.1 gm. of the drug. The alkali should be added all at once, the amount specified being slightly in excess of that required to redissolve the flocculent precipitate first formed. 3. _Concentration of the Drug._—It is important that the concentration of the drug is not greater than 0.1 gm. to 30 cc., _i.e._, 180 cc. of water for the usual dose of 0.6 gm. 4. _Method of Injection._—The gravity method only should be employed. When several patients are to be injected from the same solution, the container for the solution should be graduated. A glass stopcock is of value in controlling the flow of solution, but in its absence the rate of injection can be governed by the elevation of the fluid and by the size of the needle. A needle of 18 or 20 B. & S. gauge is best.