Anandakanda 2.1.325

2.1.325

pañcatiktaśṛtaiḥ kvāthaiḥ śuddhiṃ kuryātsuguggulum /
dolāyantre pacettāvadyāvannirmalatā bhavet //

Or with a decoction boiled with the five bitters, one should purify fine guggulu: / one should boil it in a swing-apparatus until it becomes pure.