Soon after removing to Bristol, he published, in a work entitled ‘Contributions to Medical and Physical Knowledge,’ edited by Dr. Beddoes, some essays on heat, light, and respiration. Of these it will be sufficient to say, that with much promise of future excellence, they show a most unbridled imagination, and contain many speculations so unfounded and absurd, that in after-life he bitterly regretted their publication. During his engagement, his zeal and intrepidity were signally displayed in attempts to breathe different gases, supposed, or known, to be highly destructive to life, with a view to ascertain the nature of their effects. Two of these experiments, the inhaling of nitrous gas and carburetted hydrogen are remarkable, because in each he narrowly escaped death. But his attention was especially turned to the gas called nitrous oxide, which, upon respiration, appeared to transport the breather into a new and highly pleasurable state of feeling, to rouse the imagination, and give new vigour to the most sublime emotions of the soul. The effects produced, exaggerated by the enthusiasm of the patients, were in fact closely analogous to intoxication; and many persons still remember the curiosity and amusement, excited by the freaks of poets and grave philosophers, while under the operation of this novel stimulus. In 1800 he published ‘Researches Chemical and Philosophical, respecting Nitrous Oxide and its Respiration.’ The novelty of the results announced, combined with the ability shown in their investigation, and the youth of the author, produced a great sensation in philosophical circles; and through the celebrity thus acquired, and the favourable opinion of him formed upon personal acquaintance by several eminent philosophers of the day, he was offered by the conductors of the Royal Institution, the office of Assistant Lecturer in Chemistry, with the understanding that ere long he should be made sole Professor. This negotiation took place in the spring of 1801, and on May 31, 1802, he was raised to the higher appointment.