The first time I respired nitrous oxide, the experiment was made
under a strong impression of fear, and the quantity I breathed not
sufficient, as you informed me, to produce the usual effect. I did
not note very accurately my sensations. I remember I experienced a
slight degree of vertigo after the third or fourth inspiration; and
breathed with increased vigor, my inspirations being much deeper and
more vehement than ordinary. I was enabled the next time I made the
experiment, to attend more accurately to my sensations, and you have
the observations I made on them at the time.
After the fourth inspiration, I experienced the same increased action
of the lungs, as in the former case. My inspirations became uncommonly
full and strong, attended with a thrilling sensation about the chest,
highly pleasurable, which increased to such a degree as to induce a
fit of involuntary laughter, which I in vain endeavoured to repress.
I felt a slight giddiness which lasted for a few moments only. My
inspirations now became more vehement and frequent; and I inhaled the
air with an avidity strongly indicative of the pleasure I received.
That peculiar thrill which I had at first experienced at the chest, now
pervaded my whole frame; and during the two or three last inspirations,
was attended with a remarkable tingling in my fingers and toes. My
feelings at this moment are not to be described: I felt a high, an
extraordinary degree of pleasure, different from that produced
by wine, being divested of all its gross accompaniments, and yet
approaching nearer to it than to any other sensation I am acquainted
with.
I am certain that my muscular strength was for a time much increased.
My disposition to exert it was such as I could not repress, and the
satisfaction I felt in any violent exertion of my legs and arms is
hardly to be conceived. These vivid sensations were not of long
duration; they diminished insensibly, and in little more than a quarter
of an hour I could perceive no difference between the state I was then
in, and that previous to the respiration of the air.
The observations I made on repeating the experiment, do not differ from
the preceding, except in the circumstance of the involuntary laughter,
which I never afterwards experienced, though I breathed the air several
times; and in the following curious fact, which, as it was dependent on
circumstances, did not always occur.
Having respired the same quantity of air as usual, and with precisely
the same effects, I was surprised to find myself affected a few minutes
afterwards with the recurrence of a pain in my back and knees, which I
had experienced the preceding day from fatigue in walking. I was rather
inclined to deem this an accidental coincidence than an effect of the
air; but the same thing constantly occurring whenever I breathed the
air, shortly after suffering pain either from fatigue, or any other
accidental cause, left no doubt on my mind as to the accuracy of the
observation.
I have now given you the substance of the notes I made whilst the
impressions were strong on my mind. I cannot add any thing from
recollection that will at all add to the accuracy of this account,
or assist those who have not respired this air, in forming a clearer
idea of its extraordinary effects. It is extremely difficult to convey
to others by means of words, any idea of particular sensations, of
which they have had no experience. It can only be done by making use
of such terms as are expressive of sensations that resemble them,
and in these our vocabulary is very defective. To be able at all to
comprehend the effects of nitrous oxide, it is necessary to respire it,
and after that, we must either invent new terms to express these new
and particular sensations, or attach new ideas to old ones, before we
can communicate intelligibly with each other on the operation of this
extraordinary gas.
I am &c.
JAMES THOMSON.
_London, Sept. 21, 1799._
To MR. DAVY.