Bromine reacts with substituted methyl phenyl sulphides and isopropyl phenyl sulphide in 2 : 1 methanol-water (v/v) to give the corresponding sulphoxides. The reaction follows second-order kinetics, first order in bromine and first order in sulphide. The reaction rate is increased by the presence of NaOAc and decreased by addition of NaBr in solution, The reaction is very sensitive to structural factors. It is favoured by electron-donating substituents in the phenyl ring (p-= -3.2). On the other hand isopropyl phenyl sulphide reacts about 30 times more slowly than methyl phenyl sulphide. A mechanism involving preliminary fast formation of a brornosulphonium cation followed by its rate-determining hydrolysis is suggested.

A procedure for the determination of titanium dioxide in soaps by furnace atomic absorption spectrometry is described. The method has the advantage of being rapid and simple. After the soap is dispersed in water, the titanium dioxide content is determined directly without any preliminary treatment with acids and bases to solubilize the titanium dioxide.

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A statistical investigation has been carried out on the accu. racy and precision of the analytical method of automatic determination of enzymes in detergent powders. The statistical design may be applied to any investigation in w h i h the optimizing of the number of trials is required as a function of the wanted precision and supportable costs. A table, that reports the half-range, as a percentage, of the 950/0 confidence interval on the base of the concentration values of the enzyme and carried out samplings, has been obtained. By means of this table and with suitable interpolations, every operator may fix beforehand the number of samples to examine, if a certain precision must be obtained, or conversely the range of the confidence interval got on the base of the number of samplings. The experimental data have been elaborated by a desk computer, introducing in the machine the resulting absorbance values.

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