The occurrence of helium and neon in vacuum tubes

The formation of helium and neon when the electric discharge is passed through vacuum tubes containing hydrogen was first discovered by Collie and Patterson. These results were criticised by Lord Rayleigh and by Merton, who were unable to obtain any evidence of the formation of the rare gases. In a later paper, Collie, Patterson and Masson described a further series of experiments, in which they again observed the formation of both helium and neon. Negative results were also recorded by Egerton, Piutti and Cardoso, Piutti and Harkins and Allinson. In considering the explanation of these very divergent results, mention may be made of the remarkable effects caused by changes in the type of the discharge employed. Collie and his co-workers pointed out the marked differences obtained when the hammer break on the induction coil was replaced by a mercury break, and even by the substitution of new platinum contacts on the hammer break, this change causing a definite decrease in the amount of helium formed. Attention was drawn by one of us (E.C.C.B.) to the significance of these observations, and the suggestion was made that in order to obtain positive results an optimum type of discharge was necessary and, indeed, that the divergent results obtained might be due to this cause.