Why did Sir Humphry Davy ask Samuel Taylor Coleridge and Robert Southey to inhale nitrous oxide?

Sir Humphry Davy asked his friends, including Samuel Taylor Coleridge and Robert Southey, to inhale nitrous oxide as part of his systematic investigation into the physiological effects of the gas.1

While serving as the chemical superintendent of the Pneumatic Institution, Davy was tasked with inquiring into the potential therapeutic uses of various gases. After initially inhaling the gas himself to test the erroneous claim that it was the "principle of contagion" responsible for causing diseases, he sought to broaden his data. By persuading his literary and scientific acquaintances to participate, he was able to collect and document a wider range of reports regarding the subjective effects of the gas. These findings were subsequently published in his 1800 work, Researches, Chemical and Philosophical, Chiefly Concerning Nitrous Oxide, or Dephlogisticated Nitrous Air, and Its Respiration, which solidified his scientific reputation.1