Approximations Describing the Rate of Diffusion of Dye into an Infinite Cylinder and Plane Sheet from a Constant Surface Concentration

Approximations to the Hill and McBain equations with 3–figure accuracy were obtained by dividing the whole interval of the equations into three subintervals, and making approximations to the subintervals by means of the method of Hastings. The approximations allow the calculation of the diffusion coefficient of a dye from an experimentally determined rate–of–dyeing curve.