The Treatise of Sage Uromarishi.

They did not speak out of simple kindness; they spoke in riddles.
The Siddha Konganavar (one of the 18 great Tamil Siddhas), in his teachings on Sarakku-vaippu (the complex preparation and storage of potent mineral substances), spoke with great pride, yet he did not establish the truth as clearly as the certainty of death.
He claimed that Thurusu (Blue Vitriol/Copper Sulfate) was the "Guru" In Siddha alchemy, the 'Guru' refers to a catalyst or a primary substance that transforms others—showing it well to his own followers.
In those instructions, the path of harsh caustic salts was written.
For the final conclusions of the hundred verses spoken by the great Yoga Rishi, one’s own strength and skill are simply not enough. 7.

If you say your skill is not enough, it is because he did not tell you to place it in a Kuppi (a specialized glass vial for alchemical heating) and burn it from below;
Instead, he sang of the skill of sprinkling Theeneer (literally "fire-water," referring to acids or potent distilled extracts).
Attempting shortcuts in these secret methods leads to ruin.
In the Thirumoovayiram (the "Three Thousand Verses" or Thirumandiram), there is a humble prologue.
The Singi-vithai (the alchemical art of processing cinnabar or zinc into medicine) is a lineage that will not be understood by just anyone.
Worshipping the feet of that ancient Siddha, I sing this; and this Singi-alchemy shall surely succeed. 8.

To make it succeed, they sang of the Natha-petham (the variations in the "sound" or essential vibrations of substances) for the Singi.
What comes of that? By joining it with the changing physical form and mixing it, it became known as "Singi."
If you wish for it to shine, its greatness is immense.
There is the proper method, there is medicine, there is the purging process, and there is the medicinal wax.
Purchase one Palam (a traditional unit of weight, roughly 35 grams) of Singi and crush it into a wide-mouthed clay pot. 9.

Once powdered, pour fruit juice into a ceramic vessel.
Keep it in the face of the Ravi (the Sun) until it becomes like fine sand, and then...