Anandakanda 2.6.28

2.6.28

evaṃ ṣaṣṭipuṭaiḥ paktvā nāgaḥ syāttu nirutthitaḥ /
<nāgabhasma (2)>
athavā nāgapatrāṇi cūrṇaliptāni kharpare //

and calcinating it in this manner with sixty puṭas, the lead becomes non-revivable.
<Lead Ash (2)>
Alternatively, lead sheets smeared with powder [are placed] in an earthen pan;