Ras Kapoor (Calomel) - Mercurous Chloride

Also known as: Rasa Karpura, Camphorated Mercury, Karpura Rasa, White Mercury, Hydrargyri Chloridum Mite.

Scientific name: Mercurous Chloride ($Hg_2Cl_2$).

The Alchemical Origin: Ras Kapoor is a "High-Alchemical Salt." In the ancient Rasashastra (Vedic Alchemy) and Unani traditions, it is created through a complex process of sublimation. Pure mercury is processed with salt and various botanical catalysts, then heated until it "ascends" as a white, crystalline vapor that solidifies onto the lid of the vessel.

Physical Characteristics: A brilliant, snow-white crystalline powder or heavy, porcelain-like masses. It is odorless and possesses a distinctively smooth, almost "waxy" texture that resembles the appearance of natural camphor (Karpura), giving it its name.

Chemical Profile: Unlike corrosive sublimate, Ras Kapoor is a "Mild" chloride of mercury. It is nearly insoluble in water, which traditionally made it a staple in creating stable, slow-reacting mineral formulations.

Historical Context: In the medieval laboratories of South Asia and Persia, Ras Kapoor was considered a "Noble Mineral." It was famously used by master craftsmen and practitioners as a "Catalyst" in complex mineral preparations. It has a long history in Traditional Metallurgy and was a key ingredient in the "Great Elixirs" described in the Rasa Ratna Samuccaya.

Traditional Preparation: For heritage applications, it is often "Macerated" or ground with lemon juice, milk, or herbal decoctions to "tame" the mineral and prepare it for specialized topical or technical uses.