Fractional freezing
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Fractional freezing is a process used by chemists to separate two liquids which have a different freezing point. This happens by dropping the temperature of both liquids - one liquid will reach its freezing point and solidify, while the other will remain liquid. This liquid can be poured off, leaving the solid to warm and return to its liquid state.
This process is used to increase the alcohol concentration in hard cider to make applejack, a process sometimes called freeze distillation. It is also used to make ice beer.