History of Chemistry in Ancient and Medieval India, Incorporating the History of Hindu Chemistry by Acharya Prafulla Chandra Ray c40.s2.12

c40.s2.12

The supposed thickness of the just discernible mote in the sunbeam, called a *paramanu* in technology and a *trasarenu* in Natural Philosophy, follows directly from Varahamihira's table:—8 *paramanus* make 1 *rajas* (*ratharenu*), 8 *rajas* make 1 *balagra* (filament of hair), 8 *balagras* make 1 *liksha*, 8 *likshas* make 1 *yuka*, 8 *yukas* make 1 *yava*, 8 *yavas* make 1 *anguli*, 24 *angulis* make 1 *hasta* (cubit, 18 inches). The thickness of the *minimum visible* (the finest perceptible mote in the slanting sunbeam) is, therefore, taken to be 3 × 2⁻²⁰ or 1/349525 of an inch. The volume of a spherical *trasarenu* (or *paramanu* of the *silpasastra* or technology) would, therefore, be ⅙π × 3³ × 2⁻⁶⁰ of a cubic inch. It may be here noted that such a *trasarenu* is supposed in the medical schools to contain 30 chemical atoms (*paramanus* of Natural Philosophy) according to one estimate, or 60 according to another. The size of an atom must have been conceived to be less than π × 3 × 5⁻¹ × 2⁻⁶² of a cubic inch.