History of Technology in India, Vol. I: From Antiquity to c. 1200 A.D. v1.c17.s2.t3.3
History of Technology in India, Vol. I: From Antiquity to c. 1200 A.D. v1.c17.s2.t3.3
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v1.c17.s2.t3.3
Yellow or brown stones, when exposed to the action of heat, gradually assume the red colour (characteristic of carnelian) owing to the hydrated ferric oxide losing water and becoming anhydrous.