Alternating and direct current polarograms of Cd⁺⁺ at different concentrations in the range 0·1 to 10 mM were recorded using 0·1 M potassium chloride solution as the supporting electrolyte. While the diffusion current i_d in dc polarography increased linearly with concentrations up to 10 mM, the summit current i_s at - 0·62 volts vs. S.C.E. (the half-wave potential of Cd⁺⁺) increased linearly up to 1 mM tending to saturate at larger concentrations. The potential width of the ac peaks was lower than the corresponding dc wave-spread indicating that analysis of a mixture of two components with their half-wave potentials close to each other, was possible in the ac polarography.

Alternating and direct current polarograms of cadmium were recorded at different pH values in the range 1–12. At pH < 11, cadmium was reduced reversibly at the dropping mercury electrode, giving well-defined waves on both ac. and dc. polarography. The wave-width of ac. polarograms was less than that of dc. polarograms in the entire range of pH studied.

The composition of cadmium ferrocyanide complex was investigated polarographically using KCl, KBr, KNO₃, (NH₄)₂SO₄, K₂SO₄ and NH₄Cl as the supporting electrolytes. Amperometric titrations indicated that the composition of precipitated complex was Cd₅K₆ [Fe (CN)₆]₄. The results showed the possibility of amperometric estimation of Cd⁺⁺ by Fe (CN)₆^-4 within an error 1 per cent.

The composition of nickel ferrocyanide was investigated following the amperometric titration of Ni⁺⁺ up to 40 mM. concentration against potassium ferrocyanide; it appeared to be 3 NiK₂ [Fe (CN)₆], Ni₂ [Fe (CN)₆] or Ni₅K₆ [Fe (CN)₆]₄. The data showed the possibility of estimating Ni⁺⁺ polarographically within an experimental error of 1 per cent.

Solutions of white consumption and khandsari sugar, jaggery and molasses were passed through cation-exchange resins, to eliminate the possibility of reduction of cationic substances during polarographic analysis. The solution thus obtained showed well-defined polarograms. The half-wave potential of all such technical sugar solutions was found to be ≃ 1·5 volt. The straight lines obtained between diffusion current and concentration showed the possibility of quantitative estimation of the substance reduced, which appeared to be some anionic surface active compound present in the systems. The irreversible nature of reductions of the sufrace active compounds was established. The importance of the reduction with similar half-wave potential in establishing the role of anionic substances in many sugar technological problems are expected to be established by this approach. The white consumption sugars were characterised by absence of any polarographic wave. The concentration of the reducible substance was found more in molasses than in jaggery and still less in khandsari.