An apparatus for measuring the oil and water fractions of a fluid, such as a drilling fluid. The apparatus includes a vessel body having an inner chamber coupled with a fluid inlet and an outlet. A heating element is coupled with the vessel body operable to communicate heat sufficient to vaporize a fluid within the vessel body to a gas. A gas analytical device is coupled with the outlet operable to measure components of the gas exiting the vessel body via the outlet. A rotary milling cutter translatable through the inner chamber and into solids remaining from the vaporized fluid, and having cutters operable to break solids within the inner chamber remaining from the vaporized fluid. The solids may be ejected through a solids discharge port.