SALICYLAMIDOXIME AS AN ANALYTICAL REAGENT. PART II. GRAVIMETRIC ESTIMATION OF COPPER AND NICKEL AND THEIR SEPARATION FROM OTHER METALS

The use of salicylamidoxime as a reagent for the gravimetric estimation of copper and nickel by weighing the precipitates of composition M(C₇H₇O₂N₂)₂, where M=Cu or Ni, after drying at 110^o, is described. Copper can he effectively separated from mercury^II , lead, cadmium, zinc, manganese^II and cobalt_I^I by precipitating the copper with an excess of the amidoxime at a P_H of 4.0-4.5; while for the separation from iron^III, antimony^III and bismuth^III, the precipitation should be carried out in presence of sufficient tartaric acid at P_H of 4.0-4.5. Nickel can similarly be separated from zinc quantitatively by precipitation with the reagent at a controlled P_H (7.0-7 5) in the presence of some ammonium chloride to prevent the precipitation of the latter element. Determinations of copper and nickel in mixed solutions have been carried out by precipitating copper in an acetate-buffer of P_H near about 4; in the filtrates nickel was precipitated by adding more of the reagent and then ammonia to adjust the P_H of the solution to 7.0-7.5.