II. On the new gas obtained from uraninite. Preliminary note

Extract

On the 28th of March, Professor Ramsay was so good as to send me a tube containing a new gas obtained by him from uraninite (clèveite), showing a line in the yellow which was stated to be of the same wave-length as D₃, which I discovered in 1868. This line Dr. Frankland and myself shortly afterwards suggested might be a line of hydrogen, not visible under laboratory conditions; but solar work subsequently showed that this view was untenable, although the gas which produced it was certainly associated with hydrogen. Subsequently, other chromospheric lines were found to vary with the yellow line, and the hypothetical gas which gave rise to them was provisionally named ‘‘helium,” to differentiate it from hydrogen.