Page:Edward Thorpe — History of Chemistry, Volume I (1909).pdf/31

Rh This passage accurately describes the process of madder dyeing on cotton, whereby a variety of fast colours—reds, browns and purples—can be obtained from same vat by the employment of different mordants, such as alumina, oxide of iron, or oxide of tin, etc.

Glass has been known from very early times. Representations of glass-blowing were found on the monuments of Thebes and Beni Hassan, and large quantities of glass were exported to Greece and Rome from Egypt, mainly by Phœnicians. Aristophanes mentions it as hyalos, and speaks of it as the beautiful transparent stone used for kindling fire. The Egyptians made use of various metallic oxides in colouring glass. The hœmatinon of Pliny was a red glass coloured with cuprous oxide. Cupric oxide was used to colour glass green; and ancient blue glass has been found to contain cobalt. The costly vasa murrhina of the Romans, obtained from Egypt, probably consisted of fluorspar, identical with the Blue John of the Derbyshire mines.

Stoneware has been made from time immemorial, and the Chinese have manufactured porcelain from very remote periods. Bricks and tiles were made by the Romans, and mortar and stucco were employed by the ancient Egyptians.

Soap (sapo) is mentioned by Pliny, but its detergent properties were apparently unknown