A recent theoretical study published in this journal suggests that it is possible to observe damped chemical oscillations in a system containing linear feedback and no chemical reaction. The model system consists of a loop of reactors coupled by mass transport, into which a non-reacting chemical is injected. In this Letter, we demonstrate that such oscillations correspond to the repeated passage of a chemical pulse around the closed loop. (C) 2003 Elsevier Science B.V. All rights reserved.