Chemistry in ancient India, from Harappan to Ayurvedic period
Metallurgy was intimately linked with chemistry in India. We will discuss Indian metallurgy and metal-working in a later article, focussing our attention on chemical techniques for now.
Published: 11th February 2021 07:37 AM | Last Updated: 11th February 2021 07:37 A
By M S Sriram
Chemical techniques in India can be traced back all the way to the Indus valley or Harappan civilisation (3rd millennium BCE). Following Acharya Prafulla Chandra Ray (1861-1944), the eminent Indian chemist of the last century and a historian of chemistry, five stages in its development in India can be recognised. They are: (i) the pre-Vedic stage upto 1500 BCE, including the Harappan period, (ii) the Vedic and the Ayurvedic period upto 700 CE, (iii) the transitional period from 700 CE to 1100 CE, (iv) the Tantric period from 700 CE to 1300 CE, and (v) the ‘Iatro-Chemical period’ from 1300 CE to 1600 CE. The dates cannot be considered definitive.
Metallurgy was intimately linked with chemistry in India. We will discuss Indian metallurgy and metal-working in a later article, focussing our attention on chemical techniques for now. Pre-Harappan Indians were acquainted with the art of making baked or burnt clay pottery as well as painting the same with two or more colours. This implies the construction of open and closed kilns. The pottery of the Harappan culture consisted of mainly wheel-made ware, turned in various shapes, sizes and colours out of the well-levigated alluvium of the Indus.
The colour and other characteristics of the wares depended upon the composition of the clay used and techniques of firing under either oxidising or reducing conditions. The Harappans also experimented with various mortars and cements made of burnt limestone, gypsum and mica, among other components. Finely crushed quartz, once fired, produced faience, a synthetic material; it was then coated with silica (perhaps fused with soda), to which copper oxide was added to give it a shiny turquoise glaze. Faience was then shaped into various ornaments and figurines.
Addition of iron oxide, manganese oxide, etc., resulted in different colours. The Harappan artisans must have had an intimate knowledge of the processing and properties of several naturally occurring chemical substances. The craftsmen were highly skilled in the art of shaping and polishing the precious and semi-precious stones used for the production of beads. In the second stage, Rigveda (earlier than 1500 BCE) mentions many fermented drinks and methods of fermentation, apart from various metals. Soma juice from the stems of the soma plant was highly extolled and considered a divine drink. Madhu and suraa (brewed from barley grain) also find mention.
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https://www.newindianexpress.com/opinions/2021/feb/11/chemistry-in-ancient-india-from-harappan-to-ayurvedic-period-2262489.html