The first time I inspired the nitrous oxide, I felt an highly
pleasurable sensation of warmth over my whole frame, resembling that
which I remember once to have experienced after returning from a walk
in the snow into a warm room. The only motion which I felt inclined to
make, was that of laughing at those who were looking at me. My eyes
felt distended, and towards the last, my heart beat as if it were
leaping up and down. On removing the mouth-piece the whole sensation
went off almost instantly.
The second time, I felt the same pleasurable sensation of warmth, but
not I think, in quite so great a degree. I wished to know what effect
it would have on my impressions; I fixed my eye on some trees in the
distance, but I did not find any other effect except that they became
dimmer and dimmer, and looked at last as if I had seen them through
tears. My heart beat more violently than the first time. This was after
a hearty dinner.
The third time I was more violently acted on than in the two former.
Towards the last, I could not avoid, nor indeed felt any wish to avoid,
beating the ground with my feet; and after the mouth-piece was removed,
I remained for a few seconds motionless, in great extacy.
The fourth time was immediately after breakfast. The few first
inspirations affected me so little that I thought Mr. Davy had given
me atmospheric air: but soon felt the warmth beginning about my chest,
and spreading upward and downward, so that I could feel its progress
over my whole frame. My heart did not beat so violently; my sensations
were highly pleasurable, not so intense or apparently local, but of
more unmingled pleasure than I had ever before experienced.[225]