cf. Pifer and Wollish, C.A. 46, 4952f.Solutions of the salts in acetous (anhydrous HOAc) Hg(AcO)2 (I) are titrated with HClO4 in anhydrous AcOH.Solution of an amount of alkaloidal halide equivalent to about 10 ml. of 0.1 N solution in 10 ml. of approx. 0.2 N Hg(AcO)2 converts about 50% of the Hg to HgX2.Dissolve the sample in 2-5 ml. of AcOH and 10 ml. of I, add 2 drops of 0.5% blue BZL (Ciba, Basle, CIBA 22062S) in AcOH and titrate with 0.1 N HClO4 in AcOH containing less than 0.05% H2O to a change from blue to red.When the color change is not sharp, e.g. precipitation with morphine, titrate to an intermediate reddish violet.Results between 98.7 and 100.3% are obtained for the HCl salts of ethylmorphine, cocaine, ephedrine, morphine, narcotine, dihydrohydroxycodeinone, papaverine, pilocarpine, and pyridoxine; and atropine methobromide, carbachol, and hyoscine-HBr.Diphenhydramine-HCl, terramycin-HCl, and tubocurarine Cl- were determined with 0.01 H HClO4 by using a "neutralized" Hg(AcO)2 reagent prepared by addition of 10 ml. of 0.1 N Et3N in AcOH to 100 ml. of 0.2 N Hg(AcO)2, then addition of 5 ml. of 0.5% crystal violet and 0.1 N HClO4 to the first change to green in the intermediate blue.Samples equivalent to not more than 10 ml. of 0.01 N HClO4 are suspended in 1 ml. of AcOH, 1 ml. of Hg(AcO)2 reagent is added, and the solution is titrated to the first change to green.The yellow color of terramycin necessitated the addition of 2 drops of 0.05% crystal violet in AcOH and titration to the absence of red tint in the green color.Aureomycin-HCl did not dissolve on addition of 1 ml. of Hg(AcO)2 solution and reproducible results were not obtained.