In French law. Contracts are of the following varieties: (1) Bilateral, or synallagmatique, where each party Is bound to the other to do what is just and proper; or 2) unilateral, where the one side only is bound; or (3) Commutaif where one does to the other something which is supposed to be an equivalent for what the other does to him; or (4) Aleatoire, where the consideration for the act of the one is a mere chance; or (5) contrat de bienfaisance, where the one party procures to the other a purely gratuitous benefit; or (6) Contrat d titre onereux, where each party Is bound under some duty to the other. Brown.