In the 'Proceedings of the Royal society' for 1910, there is an account of a spectroscopic investigation of the nature of the carriers of positive electricity when an electric current is sent from a glowing platinum strip covered with aluminium phosphate to a surrounding platinum electrode, the whole being contained in a highly evacuated vessel. It was found that aluminium phosphate heated under these conditions evolved carbon monoxide gas, and as a molecule of this gas earning a single electronic, charge gives a value for e/m which agrees fairly well with the mean value found for the carriers of positive electricity from beaded metals, it was concluded that the positive ions are charged molecules of carbon monoxide. Hydrogen was also detected in the gas evolved by the hot electrode in this experiment, and it now seems probable that atoms of hydrogen also take part in carrying the current, for Garrett has found that about 10 per cent, of the positive ions present when aluminium phosphate is beaded on a platinum strip in a vacuum have a mass corresponding to that of the hydrogen atom.