We report the isothermal magnetization cut-yes of a YBCO superconducting sample prepared by a flame-quench-melt-growth (FQMG) method. Hysteresis loops have been calculated and analyzed in the framework of a critical state model including the Meissner current. The bulk critical current and Meissner current as a function of applied field were extracted, and the volume fraction of the grains, f(g), has been estimated to be 0.64 from a comparison of the theoretical and experimental M-H hysteresis loops. The lower critical field, mu(0)H(c1), was found to be 14.4 mT. (C) 2000 Elsevier Science S.A. All rights reserved.