The polarography of cyclooctatetra-ene and of a new derivative, vinyl cyclooctatetra-ene, has beeh examined. Previously published work by Elofsen on cyclooctatetra-ene has been confirmed, and it has been shown that the recently isolated vinyl derivative is almost identical in polarographic behaviour with the parent compound. Both compounds give waves at the same half-wave potential, which is independent of the pH of the solution. It has also been found that cis-1-phenyl-1 : 3-butadiene is polarographically inert.

A method is described for the analysis of all mixtures of alcohol, ether and water with an accuracy of 0.2 per cent. The composition is obtained from a calibration graph constructed from data obtained by boiling-point determinations and "cloud-point" titrations. A modification to the 3-tube for the boiling-point determination has effected an improvement in technique. The . method is simple and rapid in operation, and would be applicable to other ternary mixtures containing water.

A method is described for the polarographic determination of aluminium, zinc and tin. The factors studied, which influence the reduction wave of aluminium, are the p H and the composit:ion and concentration of the base solution. Conditions have been selected for the simultaneous estimation of zinc and aluminium. The polarographic reduction of aluminium is considered to be irreversible, with a half-wave potential of -1.63 volts against the saturated calomel electrode.

A volumetric procedure is described for the assay of melamine. The addition of an aqueous solution of melamine to a 20% solution of oxalic acid in ethanol produces a crystalline precipitate of melamine mono‐oxalate. The filtered and dried oxalate may be dissolved in acid and titrated with standard potassium permanganate solution. The method is accurate to 0·3% of melamine, and small quantities of cyanogen compounds related to melamine have been shown to have slight effect on the assay.

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