Abstract
Fick's 2nd law of diffusion was solved for small values of time (the solution of error function) for the problem of diffusion in a sphere which contains a surface layer where the diffusion coefficient is higher than that in the interior of the sphere. A solution to the same problem in the conduction of heat was already obtained by Carslaw by separation of variables. The solution for the heat conduction was rewritten as the solution for the diffusion problem, and then these two types of solutions were compared with each other. There was very good agreement between them. The range of variables where the solution of error function is applicable was discussed.
