Bi2Sr2CaCu2Ox (Bi-2212) superconducting whiskers grow by annealing a melt-quenched glass precursor. We have confirmed that the Bi-2212 whiskers grow from a Bi-rich melt in this method. The bottom of the whisker is completely surrounded by the Bi-rich melt during the growth. The Bi-rich melt stays at the bottom of the whisker for a long heating duration keeping the chemical composition constant.