To clarify the adequate shape of pipe, the mixing states of emulsion in pipe were experimented about various shapes. They were understood to be the necessary conditions, that there were no level parts, no going down parts and no variable radiuses of curvature in the way of piping. Coil pipe was chosen, as it fulfilled these conditions. The mixing states of emulsion in pipe was clarified by the analysis of the mixing states of water. The characteristic curves of emulsion, acquired by the experiments on the mixing states of emulsion using a coil pipe, corresponded to the charaeteristics of emulsion, supposed from the analysis of the mixing states of water.