Ramsay’s Experiments on Copper.
§ 98. The fact that an excess of hydrogen was produced when water was decomposed by the emanation suggested to Sir William Ramsay and Mr. Cameron that if a solution of a metallic salt was employed in place of pure water, the free metal might be obtained. These “modern alchemists,” therefore, proceeded to investigate the action of radium emanation on solutions of copper and lead salts, and again apparently effected transmutations. They found on removing the copper from a solution of a copper-salt which had been subjected to the action of the emanation, and spectroscopically examining the residue, that a considerable quantity of sodium was present, together with traces of lithium; and the gas evolved in the case of a solution of copper nitrate contained, along with much nitric oxide and a little nitrogen, argon (which was detected spectroscopically), but no helium. It certainly seemed like a dual transformation of copper into lithium and sodium, and emanation into argon. They also observed that apparently carbon-dioxide is continually evolved from an acid solution of thorium nitrate (see below, [§ 100]). It is worth while noticing that helium, neon and argon occur in the same column in the Periodic Table with emanation; lithium and sodium with copper, and carbon with thorium; in each case the elements produced being of lighter atomic weight than those decomposed.[121] The authors make the following suggestions: “(1) That helium and the α-particle are not identical; (2) that helium results from the ‘degradation’ of the large molecule of emanation by its bombardment with α-particles; (3) that this ‘degradation,’ when the emanation is alone or mixed with oxygen and hydrogen, results in the lowest member of the inactive series, namely, helium; (4) that if particles of greater mass than hydrogen or oxygen are associated with the emanation, namely, liquid water, then the ‘degradation’ of the emanation is less complete, and neon is produced; (5) that when molecules of still greater weight and complexity are present, as is the case when the emanation is dissolved in a solution of copper sulphate, the product of ‘degradation’ of the emanation is argon. We are inclined to believe too [they say] that (6) the copper also is involved in this process of degradation, and is reduced to the lowest term of its series, namely, lithium; and at the same time, inasmuch as the weight of the residue of alkali, produced when copper nitrate is present, is double that obtained from the blank experiment, or from water alone, the supposition is not excluded that the chief product of the ‘degradation’ of copper is sodium.”[122]
[122] Journal of the Chemical Society, vol. xci. (1907), pp. 1605-1606. More recent experiments, however, proved that the α-particle does consist of an electrically charged helium-atom, and this view was latterly accepted by Sir William Ramsay, so that the above suggestions must be modified in accordance therewith. (See [§ 94].)