Rasahridayatantra 7.4.4

7.4.4

dravyāṇi saṃmiśrya nivṛtya bhūtale vyavasthitaṃ śastrakaṭorikāpuṭe /
saṃsthāpayetsaptadināni dhānyagataṃ prayojyaṃ rasajāraṇādikam //

Having mixed the substances, turned them out onto the ground, and placed them in an iron-bowl container,
one should keep it in grain for seven days; it is then used for the calcination of mercury and other operations.