2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/34874We show that the analysis presented in a recent comment by Coll and Ferrando \cite{comment} (qr-qc/0312058) is based on the erroneous assumption that the chemical potential and fractional concentration of a {\it mixture} of perfect fluids are unknown variables.General Relativity and Quantum Cosmologytext