The drowning-out precipitation of sodium chloride was carried out to observe nucleation phenomena by mixing two saturated aqueous ethanol solutions having different concentrations. The shape of the crystals was found to differ with the operating conditions. Crystals with hollow surfaces that may lead to a decrease in purity were observed only when the initial supersaturation ratio sigma(0) was high. From the induction time, primary nucleation was found to be predominant, with homogeneous nucleation becoming significant at sigma(0) > 0.7. The number of crystals generated increased slightly with increasing initial supersaturation ratio, but started to decrease after a certain supersaturation, where the crystals were agglomerated from the early stages of crystallization. The ＇hollow＇ crystals were generated in such high supersaturations. The crystals generated by homogeneous nucleation agglomerated readily. Since the number of crystals depended on the ethanol concentration in aqueous solution and/or the agitation condition, nucleation was strongly influenced by local mixing.