Rasahridayatantra 7.4.2

7.4.2

ānīya kṣāravṛkṣān kusumaphalaśiphātvakpravālairupetān kṛtvātaḥ khaṇḍaśastān vipulataraśilāpiṣṭagātrātiśuṣkān /
dagdhvā kāṇḍaistilānāṃ karisurabhihayāmbhobhir āsrāvya vastrair bhasma tyaktvā jalaṃ tanmṛduśikhini pacedvaṃśapākena bhūyaḥ //

Bringing alkali-trees complete with flowers, fruits, roots, bark, and shoots, then cutting them into pieces, having their bodies crushed on a very large stone and thoroughly dried,
burning them with sesame stalks, straining through cloths with elephant, cow, and horse urine, discarding the ash, one should cook that water again over a gentle flame by bamboo-boiling.