AbstractPredicted continuous phase mass transfer coefficients for fluid and solid spheres in the Stokes region of flow are correlated as Sherwood numbers plotted against Peclet numbers. These correlations permit a study of the effect of internal circulation on the rate of mass transfer from fluid spheres. At a Peclet number of 104, the theory predicts a threefold increase in transfer due to the circulation movements within a gas bubble. At a Peclet number below 10−2, the difference between a circulating and non‐circulating (or solid) sphere is indiscernible.The analysis presented in this paper for fluid spheres is based on a study by Friedlander(1)of mass transfer around solid spheres. A more elaborate concentration profile through the boundary layer has been used in the present investigation and the result reported for solid spheres differs about 8% from that given by Friedlander.The more interesting details of the mathematical treatment and the machine computation of the resulting differential equations are inclu