“Not in the ideal dreams of wild desire Have I beheld a rapture-wakening form: My bosom burns with no unhallow’d fire, Yet is my cheek with rosy blushes warm; Yet are my eyes with sparkling lustre fill’d; Yet is my mouth replete with murmuring sound; Yet are my limbs with inward transports fill’d, And clad with new-born mightiness around.” Whether, as the result of this effort, Davy ever again essayed to tempt the muse when under the influence of nitrous oxide is doubtful. Nowadays the gas is too frequently associated with unhappy memories of the dentist’s chair to call up pleasurable associations in a poet’s mind. Davy concludes his memoir with some cautious speculations as to the mode of action of nitrous oxide. That it acts on the blood he was well aware, but it has been left for subsequent research to determine in what manner. He points out that “as nitrous oxide in its extensive operation appears capable of destroying physical pain, it may probably be used with advantage during surgical operations in which no great effusion of blood takes place.” As is well known, nitrous oxide is now one of the commonest anæsthetic agents. As regards the general question how far the gases are likely to subserve the interests of medicine, he is very guarded. “Pneumatic chemistry,” he says, “in its application to medicine is an art in infancy, weak, almost useless, but apparently possessed of capabilities of improvement. To be rendered strong and mature, she must be nourished by facts, strengthened by exercise, and cautiously directed in the application of her powers by rational scepticism.” Davy’s success with nitrous oxide led him to attempt to respire other gases--such as hydrogen, nitric oxide, carbonic acid--with in one or two cases almost fatal consequences. On one occasion he tried to breathe water-gas, made by passing steam over charcoal, and was with difficulty brought to life again. These deleterious experiments, carried on with all the ardour and impetuosity of his nature, and at the expense of much nervous energy, reacted prejudicially on his health, and he was obliged to seek relaxation and quiet in the pure atmosphere of his native place. With the approach of winter he was back again in Bristol, with health restored and vigour renewed. The following letter to Mr. Davies Gilbert is interesting as fixing the time at which he entered on the path of inquiry which was to lead him to his greatest triumphs:-- “Pneumatic Institution, _Oct. 20, 1800_. “In pursuing experiments on galvanism, during the last two months, I have met with unexpected and unhoped-for success. Some of the new facts on this subject promise to afford instruments capable of destroying the mysterious veil which Nature has thrown over the operations and properties of ethereal fluids.