Rasarnava 11.173

11.173

gandhanāgadrutiṃ dattvā tāṃ mūṣāṃ suravandite
garte gomayasampūrṇe vinyasya puṭapācanam
dadyāt karīṣatuṣayoḥ prasṛtidvitayena ca //

and having given the liquefied sulfur and lead, O you praised by gods,
one should place that crucible in a pit filled with cow dung
and give a calcination fire with two handfuls of dry cow dung and chaff.