  We study the scaling properties of proton-nucleus total reaction cross
sections for stable nuclei and propose an approximate expression in proportion
to Z^{2/3}\sigma_{pp}^{total} + N^{2/3} \sigma_{pn}^{total}. Based on this
expression, we can derive a relation that enables us to predict a total
reaction cross section for any stable nucleus within 10% uncertainty at most,
using the empirical value of the total reaction cross section of a given
nucleus.
