Uptake and excretion of a new inhaled anesthetic, Forane,in vivoare consistent with its measured blood-gas partition coefficient of 1.4. The rate of alveolar change is similar to that of fluroxene and somewhat more rapid than that of halothane. Washin curves of volunteers exposed to a subanesthetic concentration and washout curves of volunteers exposed to an anesthetic concentration for six to seven hours (complete equilibration) are similar. Small, but significant, differences between the curves can be explained by differences in muscle blood flow and ventilation, or by the occurrence of ventilation—perfusion abnormalities.