The first time that I breathed the nitrous oxide, it produced feelings
analogous to those of intoxication. I was for some time unconscious of
existence, but at no period of the experiment experienced agreeable
sensations, a momentary nausea followed it; but unconnected with
languor or head-ache.
After this I several times respired the gas, but on account of the
fulness in the head and apparent throbbing of the arteries in the
brain,[222] always desisted to breathe before the full effects were
produced. In two experiments however, when by powerful voluntary
efforts I succeeded in breathing a large quantity of gas for some
minutes, I had highly pleasurable thrillings in the extremities, and
such increase of muscular power, as to be obliged to exert my limbs
with violence. After these experiments, no languor or depression
followed.