The phosphomolybdate salts Q3[PMo12O40] [Q = tetra-n-butylammonium (TBA), n-butylpyridinium (BP), cetylpyridinium (CP)] have been used as catalysts for the epoxidation of cyclooctene under organic solvent-free conditions, using H2O2 or t-BuOOH (TBHP) in water as oxidants, and compared with the BP salt of the analogous tungsten derivative, (BP)3[PW12O40]. High catalytic activities have been recorded down to very low catalyst loadings (2 ppm). The activity and selectivity depend on the oxidant and cation nature. The dominant process appears to be homogeneous and this rationalizes, together with the evolution of the phase equilibria, the presence of an induction period for the epoxidation by H2O2 and the evolution of the epoxide selectivity. The recovered catalysts are reusable and exhibit equivalent reactivity.

Various colorimetric reagents have been examined for their sensitivity in a standard method for determining aluminium in ferrous metals. Interfering elements are removed by a mercury-cathode separation followed by cupferronchloroforni extraction. In the method adopted, aluminium is determined by measuring the optical density of its complex with -Alizarin red Scalcium reagent. The method has been tested with a wide range of steels.THIS project was undertaken at the request of the Committee on Sampling and Analysis of Ferrous Metals, Standards Association of Australia, as part of its programme of developing standard methods for the analysis of steels. After a survey of published methods the authors concluded that none was completely satisfactory as a standard method applicable to all types of steels. As a result, the investigation described here was undertaken.The determination of aluminium at low levels is particularly susceptible to errors arising from the introduction of extraneous aluminium, and a high degree of analytical skill is required to prevent contamination by minute traces of this ubiquitous element. In addition to this avoidable random introduction of aluminium, there is an unavoidable pick-up of aluminium from impurities in reagents and from dissolution of aluminium from glassware. This need not be a serious problem because, in the hands of an experienced analyst, the blank from these sources can be quite reproducible. The method of analysis should be designed to keep the magnitude of this aluminium pick-up within reasonable limits. As so many analytical reagents can be a source of minute traces of aluminium, a method should in general require only small additions of reagents, restricting, in particular, the use of alkaline reagents and avoiding their contact with glass. The storage of all reagents in polythene containers reduces the risk of contamination. I t should be emphasised, however, that it is the reproducibility of the blank rather than its magnitude that imposes the lower limit to the range of aluminium that can be determined, and, in fact, the blank may be greater than the net amount of aluminium in the sample aliquot at very low levels of aluminium. I t is unlikely, howe\rer, that satisfactory reproducibility will be attained with very high aluminium pick-up.

The colorimetric nitroso-R salt method for the determination of cobalt has been critically examined. A procedure developed permits cobalt to be rapidly and accurately determined in ores, without recourse to chemical separations. The use of the differential technique of colour measurement permits up to 3 per cent. of cobalt to be determined directly in a 0.2-g sample. Higher percentages of cobalt are determined by taking a suitable aliquot of the dissolved sample. Iron in large amounts causes slightly high results and, when the iron content of the ore is known or suspected to be above 30 per cent., a smaller sample weight should be used. No other knowledge of the ore composition is necessary, as other elements do not interfere.