Anandakanda 1.2.134

1.2.134

niṣṭapte hāṭake sūtaṃ pratapte prakṣipecchive /
muhūrtātsvāṅgaśītaṃ taṃ rasaliṅgaṃ payo'ntare //

When the gold is intensely heated, O Śivā, one should cast the quicksilver into the heated [metal].
After one muhūrta, when it has cooled naturally, [one should place] that mercury-liṅga in milk.