Further experiments have been made on the production in the laboratory of the `forbidden' red and green auroral lines, and the ultra-violet transauroral line of OI. The mean concentration of oxygen atoms in the 1¹S₀ and 5⁵D states in the columns has been found from absolute intensity measurements. The decay of the green radiation produced by a Tesla discharge through a high-pressure source has been investigated with a photo-multiplier tube. It occurs at approximately the rate to be expected if the atoms in the ¹S state are undergoing spontaneous transitions to lower atomic levels, but complicating factors make it difficult to deduce transition probabilities from the experiment.