Anandakanda 2.5.58

2.5.58

ṣoḍaśāṃśena lohasya dātavyaṃ mākṣikaṃ śilā /
amlena marditaṃ ruddhvā gajākhyaikapuṭe pacet //

Mākṣika and realgar are to be added in one-sixteenth proportion of the iron. / Ground with sour [gruel], sealed, he should cook it in a single elephant-pit furnace.