Heroes of Science: Chemists

by M. M. Pattison Muir

Fig. 8.

Fig. 8 is given in order to make this "purifying" process more clearly understood. But when this process has been completed there remain, in many cases, a few short lines common to two or more elementary spectra: such lines are called by Lockyer basic lines. He supposes that these lines are due to light emitted by forms of matter simpler than our elements; he thinks that at very high temperatures some of the elements are decomposed, and that the bases of these elements are produced and give out light, which light is analyzed by the spectroscope. Such short basic lines are marked in the spectra represented in Fig. 8 with a positive sign.

Now, if the assumption made by Lockyer be admitted, viz. that the short lines, or some of the short lines, which are coincident in the "purified" spectra of various elements, are really due to light emitted by forms of matter into which our so-called elements are decomposed at very high temperatures, it follows that such lines should become more prominent in the spectra of the light emitted by elements the higher the temperature to which these elements are raised. But we know (see p. 308) that the prominences around the sun's disc are hotter than the average temperature of the solar atmosphere; hence the spectrum of the light coming from these prominences ought to be specially rich in "basic" lines: this supposition is confirmed by experiment. Lockyer has also shown that it is the "basic," and not the long lines, which are especially affected in the spectra of light coming from those parts of the solar atmosphere which are subjected to the action of cyclones, i.e. which are at abnormally high temperatures. And finally, a very marked analogy has been established between the changes in the spectrum of the light emitted by a compound substance as the temperature is raised, and the substance is gradually decomposed into its elements, and the spectrum of the light emitted by a so-called elementary substance as the temperature of that substance is increased.

But it may be urged that Lockyer's method of "purifying" a spectrum is not satisfactory; that, although all the longer lines common to two spectra are eliminated, the coincident short lines which remain are due simply to very minute quantities of one element present as an impurity in the larger quantity of the other. Further, it has been shown that several of the so-called "basic" lines are resolved, by spectroscopes of great dispersive power, into groups of two or more lines, which lines are not coincident in different spectra.

And moreover it is possible to give a fairly satisfactory explanation of the phenomena of solar chemistry without the aid of the hypothesis that our elements are decomposed in the sun into simpler forms of matter. Nevertheless this hypothesis has a certain amount of experimental evidence in its favour; it may be a true hypothesis. I do not think we are justified at present either in accepting it as the best guide to further research, or in wholly rejecting it.

The researches to which this hypothesis has given rise have certainly thrown much light on the constitution of the sun and stars, and they have also been instrumental in forcing new views regarding the nature of the elements on the attention of chemists, and so of awakening them out of the slumber into which every class of men is so ready to fall.

The tale told by the rays of light which travel to this earth from the sun and stars has not yet been fully read, but the parts which the chemist has spelt out seem to say that, although the forms of matter of which the earth is made are also those which compose the sun and stars, yet in the sun and stars some of the earthly elements are decomposed, and some of the earthly atoms are split into simpler forms. The tale, I say, told by the rays of light seems to bear this interpretation, but it is written in a language strange to the children of this earth, who can read it as yet but slowly; for the name given to the new science was "Ge-Urania, because its production was of earth and heaven. And it could not taste of death, by reason of its adoption into immortal palaces; but it was to know weakness, and reliance, and the shadow of human imbecility; and it went with a lame gait; but in its going it exceeded all mortal children in grace and swiftness."

There are certain little particles so minute that at least sixty millions of them are required to compose the smallest portion of matter which can be seen by the help of a good microscope. Some of these particles are vibrating around the edge of an orb a million times larger than the earth, but at a distance of about ninety millions of miles away. The student of science is told to search around the edge of the orb till he finds these particles, and having found them, to measure the rates of their vibrations; and as an instrument with which to do this he is given—a glass prism! But he has accomplished the task; he has found the minute particles, and he has measured their vibration-periods.

Chemistry is no longer confined to this earth: the chemist claims the visible universe as his laboratory, and the sunbeams as his servants.

Davy decomposed soda and potash by using the powerful instrument given him by Volta; but the chemist to-day has thrown the element he is seeking to decompose into a crucible, which is a sun or a star, and awaits the result.