A new method, differential dissolution (DD), was used to characterize the real stoichiometry of 2-3 mm(2) Bi-2212 samples, which looked like single crystals according to optical microscopy. The shape of the dissolution kinetic curves, used as an indicator of the crystalline state, has shown that the crystals are not real single crystals, but consist of thin single-crystal layers packed along the c axis. The stoichiogram values recorded as a function of time or crystal dissolution degree were used to determine the composition and thickness of each layer, as well as the composition of the interfaces. The results obtained by the DD method, along with data from other techniques, are discussed in terms of the chemical inhomogeneity of Bi-2212 crystals grown by different methods.