the measurement signals from measuring members 2 u2032 3 u2032 can be alternately recorded separately of each other formed close to the other end of measuring device 61 is a chamber 7 for providing a homogenous quantity of liquid therein a reference measurement is performed on this homogenous quantity of liquid so that by means of calculations differences in the conductivity of the liquid flowing by such as milk in homogenous form can be eliminated from the calculations on the basis of the measuring members where in the preferred embodiment according to fig1 there are two electrodes for supplying the measurement signal and performing the measurement in this preferred embodiment there are two work electrodes 64 65 for providing the signal and two measuring electrodes 5 u2032 6 u2032 electrodes 5 6 respectively in fig8 for performing the measurement it is therefore also the object in this preferred embodiment to perform the reference measurement close to the height measurement so that the variations in the conductivity of the fluid can be eliminated in isolation shown schematically in fig1 is the method of the embodiment according to fig6 7 the measurements by means of respective measuring members 2 u2032 3 u2032 are shown in parallel on the left hand side of the figure a value for the resistance is provided in step 72 72 u2032 the reference value is provided in step 75 on the basis hereof in combination with the temperature from.