It is noted that significant (but usually & # 171; shadow & # 187;) parameters of magnetic separation of liquid-dispersed media (suspensions, including ceramic, for the separation of the dispersed phase of impurities of ferroparticles) are their dynamic viscosity and density of the medium. The temperature dependences of the viscosity of the slip and its dispersion component (water) are compared, variants of their description in the operating temperature ranges by functions of exponential and logarithmic forms, respectively, are given, which may also be valid for other media, including those used for other, non-industrial, purposes. The functional form of such a dependence for a slip is used in basic expressions for the efficiency and limiting rate of its filtration magnetic separation - with a convenient in practice legalization of the slip temperature in these expressions