Rasarnava 4.7

4.7

dravadravyeṇa bhāṇḍasya pūritārdhodarasya ca
mukhe tiryakkṛte bhāṇḍe rasaṃ sūtreṇa lambitam
taṃ svedayet talagataṃ dolāyantramiti smṛtam //

In a pot whose belly is half filled with liquid substance,
with the pot placed horizontally at the mouth, mercury suspended by a thread
is steamed, hanging above the bottom; this is called the Dolāyantra.