Abstract: A method for determining the spatial and phase distribution of a liquid-vapor multiphase fluid. The method comprises adding a fluorescent monomer and a quencher to the fluid to be studied. The fluid is then dispersed and the monomer excited. The excited monomer combines with the quencher to form a fluorescent exciplex. The monomer fluorescence is predominantly in the vapor phase and the exciplex fluorescence is predominantly in the liquid phase.

Abstract: Process and apparatus for directly measuring the ion strength of an electrolyte solution is disclosed. The pH value of the electrolyte is measured by means of a first measurement with a first indicator dependent on the ion strength and by means of a second measurement with a second indicator dependent on ion strength in a manner different from the first indicator whereby the ion strength is computed by means of the approximation ##EQU1## J=ion strength Jo=ion strength upon calibrationpH'(N)=pH value, measured with a first indicator N dependent on the ion strength (HPTS)pH'(X)=pH value, measured with a second indicator X dependent on the ion strength, the ion strength dependence of which is different from that of the first indicatorW(N)=valency of the first indicatorW(X)=valency of the second indicatorwith ##EQU2## The ion strengths of other ions and of unknown electrolyte may also be computed.