Page:Popular Science Monthly Volume 42.djvu/451



LONG the eastern base of the Rocky Mountains there is found a hard, dark mineral known as obsidian, or volcanic glass. It is a variety of feldspar. In the chemical sense, it is a true glass, since it is a silicate of at least two metals, aluminium and potassium. Physically, it half deserves the name. Though too dark to be transparent, it is at least translucent; and in its luster, hardness, and glassy fracture it is quite comparable to the products of industrial glass-houses. Travelers in New Mexico are offered bits of this volcanic glass by the Pueblo Indians who congregate at Wallace and other dining stations along the railroad.

The manufacture of glass in America seems, then, to have been first set up by Nature, and may easily claim priority to all our other industries. It was one of the native products used in the early receptions given to the invading white man; but lest the spirit of the hospitality be misunderstood, it should be added that it was served in the form of swiftly flying arrowheads. When Columbus came to this country the glass industry was limited to a rude fashioning of the material supplied by Nature. It had been melted in fires burned out long centuries before.

In the Europe of 1492, the operations of glass-making were still very crude and inadequate. It was a rare thing to have glazed windows, even in castle and palace. For many years the luxury was limited to the churches, and there it was an article of decoration rather than of utility. In domestic service, the supply of