A test for water mud or oil mud, generally known as the retort test. Proper procedures for retort tests have been published by API. The test is a distillation of a mud sample that measures condensed oil and water collected from the retort. Data obtained are: (1) vol. % water, (2) vol. % oil and (3) vol. % retort solids. Retort solids is the volume that was not recovered as a liquid. Three sizes of retort apparatus are available: 10-, 20- and 50-cm³ mud sample size. Some designs have a small oven in the carrying case to heat the sample (the preferred method for oil muds) while others use a blade heater that goes into the mud sample. Retorts should be heated to around 700掳F (371掳C) to be effective.