Glass, given its durability and versatility, plays an important role in human culture. Generally manufactured by heating sand (silica), soda (alkali), lime, and other ingredients at high temperature, glass is a fundamental component of a variety of products, including tableware, windshields, thermometers, and telescope lenses. Early peoples were likely to have discovered natural glass, which is created when lightning strikes sand, and were certain to have used obsidian--a dark volcanic glass--for weapons, ornaments, and money. The first manmade glass probably took the form either of glass beads or ceramic glaze and appeared around 4000 to 5000 b.c. Surviving examples of Egyptian and Mesopotamian glass objects date to around 1550 b.c. For centuries glass, shaped by the use of molds, remained costly and difficult to produce. The invention of the blowpipe method of glassmaking (in which molten glass is puffed into shape with the use of a hollow tube) in...