At the TX-100 and CTAB mixture concentration in the solutionat which its micelles can be present (Figs. 9 and S19), the changesof as a function of ethanol concentration are quite different fromthat at the mixture concentration lower than CMC. The conductiv-ity changes in the range of low ethanol concentration almost in the same way as the apparent molar volume of ethanol. The decrease of conductivity is connected with the decrease of the CTAB dis-sociation both in the monomeric form and in the micelles. On theother hand, as the measurements of the micelle size indicate, themicelle size decreases as a function of ethanol concentration inthe range in which alcohol is present in the monomeric form insolution. It is possible that the micelle density changes also in thisrange of ethanol concentration. It is also probable that the degreeof counterion binding to the surface active ion increases slightly ina certain range of ethanol concentration. Due to the effect of thesemagnitudes on the conductivity, the minimum of (Figs. 9 and S19)is observed on the isotherms of conductivity in the range of ethanolconcentration in which the presence of TX-100 and CTAB mixedmicelles cannot be excluded. The changes of the degree of thecounterion binding to the surface active cation and of the size ofthe micelles are confirmed by the changes of the conductivity as afunction of the TX-100 and CTAB mixture concentration and onlythe CTAB concentration (Figs. 4 and 10). The values of CMC deter-mined from the conductivity changes as a function of surfactantmixture concentration at the constant ethanol concentration equalor higher than 1.07 M are considerably larger than those obtainedfrom the surface tension, density and viscosity isotherms (Table 3).If the conductivity is plotted against the CTAB concentration(Fig. 10), then the influence of TX-100 in the mixture in the bulkphase on is evident over the surfactant mixture concentrationhigher than CMC. At the same CTAB concentration, the bigger molefraction of TX-100 in the bulk phase, the bigger value of the specific