Anandakanda 1.23.258

1.23.258

māsamātraprayogeṇa pannagaḥ kāñcanaṃ bhavet /
<mercury:: paṭṭabandha>
grāhyaṃ tatphalatailaṃ tu yantre pātālasaṃjñake //

After merely a month's use, lead becomes gold.
<Paṭṭabandha of mercury>
The oil of its fruit should be collected in the apparatus called pātāla.