Cohobation

In pre-modern chemistry and alchemy, cohobation was the process of repeated distillation of the same matter, with the liquid drawn from it; that liquid being poured again and again upon the matter left at the bottom of the vessel.

Cohobation is a kind of circulation, only differing from it in this, that the liquid is drawn off in cohobation, as in common distillation, and thrown back again; whereas in circulation, it rises and falls in the same vessel, without ever being drawn out.