The surface tension of water $\gamma$ 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.),
$$
\gamma=75.796-0.145 \theta-0.00024 \theta^{2}
$$
where $\theta$ is the Celsius temperature. Caiculate the change of surface tension with respect to temperature $\theta, d \gamma / d \theta$, at $10^{\circ} \mathrm{C}$ and $60^{\circ} \mathrm{C}$.