Rasahridayatantra 2.7

The lower vessel should be eight aṅgulas in width and ten aṅgulas in length, / elevated four aṅgulas below the neck, and furnished with a water receptacle.

The mouth of the lower vessel is entered inside, with the rim of its own mouth submerged in water; / above, a flat earthen vessel should be placed, sixteen aṅgulas wide at the belly.

Distilled in that upper vessel, completely freed from all defects, / the king of mercuries becomes exceedingly fit for substance [transmutation] and for rejuvenation therapy.

Having made a lost amalgam with the three fruits, peacock-flower, drumstick, mustard seeds, and salts, / and having smeared it in the upper vessel, it is to be distilled downwards with burning cow-dung cakes.

Or else, distilled in a lamp apparatus, freed from all defects, / the king of mercuries is to be distilled according to the procedure of transverse distillation.

Powdered mica leaf combined with the king of mercuries and fermented gruel, / placed in a mortar, is triturated until it becomes a lost amalgam.

One should subject the mercury to transverse distillation gradually over a steady fire; / having been thoroughly steamed, it is distilled so long as the steady fire does not drop.

Troubled by trituration, swooning, and distillations, it exhibits sluggishness of potency; / through confinement with earth lotuses, having regained vitality, it does not become impotent.