fractional distillation
noun [ U ] chemistry specialized uk/ˌfræk.ʃən.əl dɪs.tɪˈleɪ.ʃən/ us/ˌfræk.ʃən.əl dɪs.təˈleɪ.ʃən/
分馏（化学过程，将液体混合物加热，使其中沸点不同的各个物质气化，再分别冷却收集，从而得到分离）
the chemical process of separating different substances that have different boiling points by heating a liquid mixture until it turns into gas and then cooling and collecting each substance separately