The Romance of Modern Chemistry

CHEMISTRY OF THE STARS what is the composition of the sun’s atmosphere—the chromosphere, as it is called. Among the elements which are thus proved to be present in the sun are hydrogen, sodium, calcium, barium, magnesium, iron, zinc, and copper. The reader will see that so far as the mere elements go, there is nothing very strikingly novel about the composition of the sun, but there is probably a considerable difference between the earth and the sun in the extent to which the elements are combined. On the earth the elements just named are almost without exception found in the form of com- pounds, but at the high temperature of the sun all ordinary compounds will have undergone dissociation into their constituent elements. It appears pretty certain that the temperature of the sun is not below 10,000° Fahrenheit, in comparison with which the electric furnace, our best attempt at producing a high temperature, is miserably cold. Similar conclusions as to the composition of the stars have been drawn from their spectra, and it appears that the elements entering into their composition are pretty much those with which we are familiar. Astronomers have actually ventured a step farther, and endeavoured to estimate the approximate temperature of each star from the character of its spectrum. This attempt is based on the observation that the spectrum of an element varies somewhat according to the way in which it is vaporised. According as the substance is exposed to the action of a flame, of the electric arc, or of the electric spark, a different spectrum is produced. The conclusions which astronomers have drawn from these observations are deeply interesting ; but that is another story. A very curious fact in connection with the application 212