We show that the so-called original expression for a dilute random medium derived recently by Skipetrov [Phys. Rev. B 60, 12 705 (1999)] is apparently just the well-known Maxwell-Garnett formula. By comparing another of Skipetrov’s original expressions and the Maxwell-Garnett formula and its extensions, we notice that his expression, only valid for small heterogeneities, always gives higher results than the Maxwell-Garnett formula and its extensions. The comparison illustrates that Skipetrov’s expression is not particularly superior to the Maxwell-Garnett formula and its extensions.

• Received 25 May 2000

DOI:https://doi.org/10.1103/PhysRevB.63.176201