Anandakanda 1.23.238

1.23.238

sthālīsampuṭayantreṇa dinaṃ caṇḍāgninā pacet /
ūrdhvalagnaṃ tataḥ śubhraṃ mūrchitaṃ cāharecchubham //

With an apparatus of covered cooking pots, one should cook it for a day with an intense fire;
then one should take out the pure, auspicious, swooned [mercury] adhering to the upper part.