Where a plain alembic sends its condensate out of the apparatus entirely, the pelican sends it back in. Two curved tubes, the vessel's defining feature, rise from the shoulders of its rounded body and arc back down into that same body, rather than draining out through an open spout to an external receiver. Heat applied to the base of the vessel drives the more volatile part of the liquid up into the dome at the top, where it cools and condenses just as it would in any still head; but instead of escaping, the condensed liquid runs down the two return arms and drips straight back into the pool it rose from. That returning liquid is immediately re-heated and re-distilled, over and over, for as long as the operator keeps the vessel over gentle, steady heat, which could mean days or weeks of continuous slow circulation rather than a single pass lasting hours.
Because nothing is ever removed until the operator chooses to open the vessel, circulation in a pelican is less about separating one substance from another by boiling point, the job an alembic or retort does well, and more about repeatedly refining and subtly transforming a liquid through prolonged, gentle self-distillation, an operation alchemical texts describe as softening or maturing a substance rather than purifying it in a single step.