Eble estas permeseble konjekti ke elektronoj estas malgrandaj, kaj atomoj de heliumo pli grandaj sekvanteroj. Sed preterdaŭrigi la temon, sen difina koniĝo, kiu nur povas riceviĝi per eksperimentoj, estus malutile.
Kompreneble multe da laborantoj, kiel eble plej ili povas, en la nuna tempo penadas por eniĝi pli profunde en tiujn interesegajn regionojn de esplorado.
RADIUM.
By Sir William Ramsay, K.C.B., F.R.S.
The strange qualities of radium, especially its brilliance in the dark and its power of illuminating some other bodies, attracts the attention of the entire world. This radium is, we believe, a metal, although till now it has not been produced in metallic form, for its salts are similar to the salts of barium, a white metal and a well-known element. The reason is that so little of these salts is available that it cannot be wasted in experimenting to effect the change from a salt into a metal, for the loss would be great. The best-known salt, the bromide, costs twelve shillings per milligram, an almost invisible quantity.
All metals have their peculiar spectra. If their salts be heated in a flame, on examining them by means of the spectroscope, coloured lines peculiar to each metal may be seen, which are named its "spectrum." Thus a metal is recognisable from its spectrum. Radium has its particular spectrum, which is like the spectrum of barium, but different in the location of the lines. We therefore believe that radium is an element similar to the other metals.
From the salts of radium a gas continually escapes, which has the quality of shining in the dark, remaining warm the while, and it throws out bodies known as electrons. When these bodies touch the air or any gas they impart to that gas the power to discharge an electroscope. While this gas is giving forth heat and discharging electrons it gradually vanishes, and instead another gas appears, of low density, the spectrum of which M. Janssen, a famous French astronomer, noticed in the light of the sun during 1868, and which was first discovered on the earth by the writer of this article.
It seems, therefore, that one element, radium, can produce another—namely, helium. Whether, as is possible, other elements are formed at the same time we do not know. That question remains for further investigation.
Let us see whether radium possesses any properties, differing in kind or in degree, from those of other elements which have not yet been observed to undergo any such extraordinary change.
First, then, there are, at least, other two elements which discharge electrons. These are thorium and uranium. They all, as well as radium, undoubtedly consist of atoms of great weight. If we take the weight of an atom of hydrogen as unity, that of radium weighs about 225 (or perhaps even more); that of thorium 232, and that of uranium 240.