Anandakanda 2.1.19

2.1.19

taddhuttūradravaiḥ piṣṭvā śuṣkaṃ drāvyaṃ ca pūrvavat /
punarevaṃ prakartavyaṃ suśuddho gandhako bhavet //

Having ground that with dhuttūra juice, dried it, and melted it as before, / this should be done once again; the sulphur will become thoroughly purified.