Abstract: This paper explains by a series of examples the use of the notion of a Chemical Abstract Machine. This is a framework for parallel computations which builds upon the chemical metaphor of Banatre and Le Métayer. We first illustrate the CHAM style by describing the operational semantics of process calculi constructs. Then we apply our approach to the lambda-calculus, designing a CHAM for the weak beta-reduction with sharing, and specializing it into a CHAM for the call-by-need reduction strategy. Our last example is the pi-calculus. We discuss the notions of ``asynchronous'' and ``fully asynchronous'' reductions, and some pi-calculus encodings of the lambda-calculus.