A volume of 350 cm³. In mud laboratory experiments, 350 cm³ is the volume chosen to represent 42 US gallons (1 oilfield barrel) (6. 6 m³), so that 1. 0 gram mass represents 1. 0 lbm. This is a convenient concept for mud technicians to use when mixing or pilot-testing mud samples. For example, in preparing a mud formulation or for pilot-testing purposes, adding 1. 0 grams to 350 cm³ of fluid is the experimental equivalent of adding 1. 0 lb to 42 gallons (1. 0 bbl) of fluid.