Anandakanda 2.6.35

2.6.35

yāmaikaṃ pācayeccullyāṃ samuddhṛtya vimiśrayet /
saṃcūrṇya ca śilātāpye vāśakakṣārasaṃyutam //

One should cook it on a hearth for one yāma, take it out, and mix it;
and having pulverized it with realgar and copper pyrites along with the alkali of vāsaka,