The surface tension of water in dynes per centimeter is

Question

The surface tension of water, in dynes per centimeter is given by the empirical equation (W. D. Harkins: The Physical Chemistry of Surface Films, Reinhold, New York, 1952, p. 76.),

γ= 75.796 - 0.145θ - 0.00024θ²,

Where θ is the Celsius temperature. Calculate the change of surface tension with respect to temperature θ, dγ/dθ , at 10° C and 60° C.