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The quasi-chemical approximation is applied to the calculation of adsorption isotherms for two-component surfactant systems. No further approximations are necessary. The effects of the relative sizes of the interaction energies of the various nearest neighbor pairs are investigated, and plots of representative adsorption isotherms are given. Some possible applications of the theory to foam flotation and other surface chemical separation techniques are suggested.

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We discuss here the partial differential equations governing the migration of a decomposing pollutant adsorbing according to a Langmuir isotherm and undergoing 2-dimensional flow in a saturated aquifer. The equation governing the mass transfer of the pollutant to the surfaces within the aquifer are solved in closed form, permitting the use of larger values of the time increment Δt in the numerical integration of the dispersion-advection equation governing the behavior of the dissolved pollutant. In this numerical integration transverse numerical dispersion is eliminated by using conformal coordinates (velocity potential and stream function), and longitudinal numerical dispersion is very substantially reduced by use of an asymmetrical 4-point formula to represent the advection term. Some representative results are given as contour maps. The mass transfer rate coefficient is estimated as the least positive eigenvalue of a diffusion problem.

The recent revelation that many unleaded gasolines contained an organomanganese antiknock compound was a surprise to many who thought that they were using gasoline without polluting metal additives. In these cases a black exhaust pipe deposit which might be mistaken for carbon is indicative of the presence of manganese. A 0.01-g sample of the deposit is treated with 1 ml of dilute nitric acid, heated to boiling, then cooled and sodium bismuthate added. The mixture is then subjected to centrifugation in order to better determine whether or not the characteristic permanganate ion color is present in the supernatant solution. It is also possible to examine spark plug deposits in the same manner.