The Gibbs principle for the equilibrium of systems with two simple or composed phases

Summary A precise formulation of the Gibbs principle is proposed and the equilibrium equations for systems having two phases of the same substance are derived and discussed when: a) one of them is solid, isotropic and elastic and the other one is liquid or vapour and both the phases are simple, b) one is liquid and the other is vapour of the same binary mixture. Some final remarks are provided for the case of crystal phases.

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Sommario Viene proposta una rigorosa fomulazione del principio di Gibbs; vengono derivate e discusse le equazioni per l'equilibrio di un sistema formata da due fasi di una stessa sostanza, quando: a) la sostanza é semplice; b) una é liquida e l'altra é di vapore di una stessa miscela binaria. Alcune considerazioni finali riguardano il caso in cui la fuse solida é cristiallina.

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Work supported by the Italian C.N.R.