A scaled SU(3) Nambu - Jona-Lasinio Lagrangian is used to compute the mass of
the nine scalar mesons in the vacuum and the mass of the gluball. It is shown
that a suitable choice of the vacuum gluon condensate allows to reproduce the
experimental masses of the scalar mesons except for the {K0∗​}(1430). This
choice corresponds to a weak coupling between the gluon and quark condensates,
giving a {f0​}(1500) or a {fJ​}(1710) which is nearly a pure glueball.Comment: 12 pages, Latex, use elsart.st