Anandakanda 2.2.29

2.2.29

kṣiptvādāya tu taccūrṇaṃ tattulye gandhamākṣike /
amlena mardayedyāmaṃ ruddhvā laghupuṭe pacet //

taking that powder, [and adding] an equal amount of sulfur and pyrite, / one should grind it with sour liquid for one watch, seal it, and cook it in a light calcination pit.