Lecocq first found that the sensitivity of diphenylcarbazide test for molybdate ions in mineral acid medium was 1:2.6×10⁵ (it is assumed that he used commercial ammonium molybdate), and Schmitz-Dumont reported a value of 1:2×10⁶ in acetic acid solution. In the present investigation, it is found that the sensitivity is still higher (1:5×10⁷) when the test is carried out in the neutral medium (and in test tubes with an inner diameter of 10 mm). Evidently the sensitivity is greatly influenced by the concentration of hydrogen ions. The use of the diphenylcarbazide as a qualitative reagent for tungstate ions has not yet been recorded before. It is found that in the neutral medium the sensitivity of the test is 0.1 [D]⁵, which is the same as that for molybdate under similar conditions.