3-OXIMINOME THYLSALICYLIC ACID AS AN ANALYTICAL, REAGENT. PART I. GRAVIMETRIC ESTIMATION OF COOPER AND NICKEL

The reactions or 3-oximinomethylsslicylic acid with metallic ions have been fully investigated. It has been found that this reagent behaves very much like salicylaldoxime with respect to colour, solubility, etc. of its metallic derivatives ; but the pH values of incipient precipitation of the metallic ions are somewhat different from those found with salicylaldoxime. Like sali­cylaldoxime this reagent has also been found to produce an orange-yellow precipitate with titanium in acid solution, though Flagg and Farman (lid. Eng. Chem, Anal. Ed.., 1910, II, 529, 653) did not notice this characteristic reaction of salicylaldoxime. FeIII and UVI yield soluble coloured complexes in acid and alkaline medium respectively. The use of 3-oximinomethylsalicylic acid as a reagent for the gravimetric estimation of copper and nickel, which famish precipitates of composition M(C5H3O2N)2, (M=CuII or NiII), after drying at 110°, has been described. Copper can be effectively separated from HgII, PbII AlIII, CdII ZnII. MnII and CoII by precipitating it with an excess of 3-oximinomethylsalicylic acid at pH 2.5 to 3.0 ; while for its separation from FeIII, SbIII and BiII, the precipitation had to be carried out in the presence of sufficient tartaric acid at pH 2.5 to 3.0- Determination of copper has also been made from solutions containing arsenite, arsenate, vanadate and phosphate at pH 2.5 to 3.0. Nickel has been estimated gravimetrically with this reagent at a controlled pH (5.6-6.0