Consider the precipitation of a spherical B$-$rich phase $($ phase$)$ from a dilute solution $($ phase$)$ of B in A$.$ Suppose the original concentration of $B$ in the solid solution is $C_0=5{10}^{21}$ atoms $\frac{?}{c{m}^3},$ the diffusion coefficient of $B$ is $D=2{10}^{-10}c\frac{m^2}{sec},$ and the interface transfer parameter of $B$ is $M=2{10}^{-6}c\frac{m}{sec}.$ The equilibrium concentration of $B$ in the $$ and the $$ phases and $($:$C_{}$