History of Chemistry in Ancient and Medieval India, Incorporating the History of Hindu Chemistry by Acharya Prafulla Chandra Ray c15.s1.44

c15.s1.44

According to Sanaullah the presence of lime and magnesia increased the fusibility of the silicate layer of the surface, rendering the latter highly polished and hard. That carbon particles are also deposited in the pores of the wares during burning in a smoky atmosphere, when some tarry matter is condensed on the surface, has been confirmed by him.