Rasarnava 6.38

6.38

grāhayedabhrapatrāṇi nikṣipyāmle dinatrayam
lepayettena kalkena kāṃsyapātre nidhāpayet
sūryyatāpena saptāhaṃ drutiḥ sañjāyate kṣaṇāt //

One should take the mica sheets, throw them into sour [liquid] for three days, / smear them with that paste, and place them in a bell-metal vessel; / by the heat of the sun for seven days, liquefaction is produced in an instant.