ship; and the chemist can easily discover, amidst the crowd of lines in the solar spectrum, the pattern corresponding to the various substances. In this way, iron, magnesium, chromium, sodium, and nickel, have been found in the sun's atmosphere. On the other hand, no trace has been found of silver, copper, zinc, aluminium, cobalt, and mercury, though they have very characteristic spectra.
It may be objected, that it is a mere assumption, that the brighter opaque photosphere of the sun is shining through a gaseous atmosphere. This, however, is not the case. These precise conditions can be represented artificially, and the same results obtained. The charcoal points in the electric light, represent the opaque incandescent photosphere of the sun. A Bunsen's lamp, which gives a great heat without much light, represents, with substances diffused in its flame, the gaseous envelope of the sun. When the flame of the lamp is viewed with the brighter electric light as a background, phenomena precisely similar to those of the solar spectra are observed. The only difference is, that in the lamp we can diffuse any one substance at a time and get its spectrum isolated, while, in the sun's atmosphere, numerous substances are diffused, and we have thus various spectra mixed up together.
But this spectrum analysis is not confined to the sun. We can now analyse the remotest stars that
