Cohobation

Bottle with curved pouring pipe for cohobation at the Museo Galileo, Florence

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.^[1] 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.^[2][3]

References

1. "Cohobate"; "Cohobation". Oxford English Dictionary. Oxford University Press. 2nd ed. 1989.
2.  This article incorporates text from a publication now in the public domain: Chambers, Ephraim, ed. (1728). "Cohobation". Cyclopædia, or an Universal Dictionary of Arts and Sciences (first ed.). James and John Knapton, et al.
3. This article incorporates text from a work in the public domain:  Porter, Noah, ed. (1913). "Cohobation". Webster's Dictionary. Springfield, Massachusetts: C. & G. Merriam Co.