Abstract : Weintroducea new kind of abstract machine based on the chemical metaphor used in the G language of Banatre & al. States of a machine are chemical solutions where floating molecules can interact according to reaction rules. Solutions can be stratified by encapsulating subsolutions within membranes that force reactions to occur locally. We illustrate the use of this model by describing the operational semantics of the TCCS and CCS process calculi. We also show how to extract a higher-order concurrent l-calculus out of the basic concepts of the chemical machine.