A ray of light separated by a prism or otherwise into the colors of which it is composed. There are seven different bands of color -red, orange, yellow, green, blue, indigo, and violet. The spectrum of solar light or that of the light given off by burning bodies, is found to be crossed by very many dark lines or spaces where the light is inter-rupted. These are known from their discoverer, as the Fraun-hofer lines. If the substance burned is a gas, its lines are bright instead dark, and the rest of the spectrum is dark. Each sub-stance makes a dif-erent set of lines, and spectrum analysis is a method of examining the lines in any ray of light and determining by them what substance yields the ray. By this means it has been found that many earthly substances exist in the sun, such as hydrogen, iron, sodium, etc. Similar substances have been found in very distant stars. Many of the nebulae give a spectrum of bright lines, from which we conclude, that they are composed of luminous gaseous matter.

Spectrum Red Blue

Spectrum Red Blue