10.9 For low viscosity transparent or translucent liquids
depress the hydrometer about two scale divisions into the
liquid, and then release it, imparting a slight spin to the
hydrometer on release to assist in bringing it to rest floating
freely from the walls of the hydrometer cylinder. Ensure that
the remainder of the hydrometer stem, which is above the
liquid level, is not wetted as liquid on the stem affects the
reading obtained.