  An experiment is proposed in which the Aharonov-Bohm effect can be veryfied
through a spectroscopic measurement. The apparatus consists of gaseous
hydrochloric acid (HCl) immersed in the vector potential ${\bf A}$ present in
the center of a toroidal coil, where ${\bf B}=0$. Changes due to ${\bf A}$ in
the absorption spectrum of the gas are investigated.
