  We solve the site-site Ornstein-Zernike equation using the Percus-Yevick
closure for binary hard-sphere mixture. We calculate an excess chemical
potential for the mixture's diameter ratios of 0.3, 0.5, 0.6 and 0.9, and at
packing fraction of 0.49 using the analytical expression. Our numerical results
are in good agreement with those in the literature.
