After having breathed five quarts of gas, I experienced for a short
time a quickness and difficulty of breathing, which was succeeded by
extreme languor, resembling fainting, without the very unpleasant
sensation with which it is usually attended. It entirely deprived me of
the power of speaking, but not of recollection, for I heard every thing
that was said in the room during the time; and Mr. Davy’s remark “that
my pulse was very quick and full.“ When the languor began to subside,
it was succeeded by restlessness, accompanied by involuntary muscular
motions. I was warmer than usual, and very sleepy for several hours.