_HISTORY of the DISCOVERY.—Effects produced by the
RESPIRATION of different GASES._
A short time after I began the study of Chemistry, in March 1798,
my attention was directed to the dephlogisticated nitrous gas of
Priestley, by Dr. Mitchill’s Theory of Contagion.[204]
[204] Dr. Mitchill attempted to prove from some phænomena connected
with contagious diseases, that dephlogisticated nitrous gas which he
called oxide of septon, was the principle of contagion, and capable of
producing the most terrible effects when respired by animals in the
minutest quantities or even when applied to the skin or muscular fibre.
The fallacy of this Theory was soon demonstrated, by a few coarse
experiments made on small quantities of the gas procured from zinc and
diluted nitrous acid. Wounds were exposed to its action, the bodies of
animals were immersed in it without injury; and I breathed it mingled
in small quantities with common air, without remarkable effects. An
inability to procure it in sufficient quantities, prevented me at
this time, from pursuing the experiments to any greater extent. I
communicated an account of them to Dr. Beddoes.
In 1799, my situation in the Medical Pneumatic Institution, made it my
duty to investigate the physiological effects of the aëriform fluids,
the properties of which presented a chance of useful agency. At this
period I recommenced the investigation.
A considerable time elapsed before I was able to procure the gas in a
state of purity, and my first experiments were made on the mixtures of
nitrous oxide, nitrogene and nitrous gas, which are produced during
metallic solutions.
In the beginning of March, I prepared a large quantity of impure
nitrous oxide from the nitrous solution of zinc. Of this I often
breathed the quantities of a quart and two quarts generally mingled
with more than equal parts of oxygene or common air. In the most
decisive of those trials, its effects appeared to be depressing, and
I imagined that it produced a tendency to fainting: the pulse was
certainly rendered slower under its operation.
At this time, Mr. Southey respired it in an highly diluted state; it
occasioned a slight degree of giddiness, and considerably diminished
the quickness of his pulse.
Mr. C. Coates likewise respired it highly diluted, with similar effects.
In April, I obtained nitrous oxide in a state of purity, and
ascertained many of its chemical properties. Reflections upon these
properties and upon the former trials, made me resolve to endeavour
to inspire it in its pure form, for I saw no other way in which its
respirability, or powers could be determined.[205]
[205] I did not attempt to experiment upon animals, because they die
nearly in equal times in non-respirable gases, and gases incapable of
supporting life and possessed of no action on the venous blood.
I was aware of the danger of this experiment. It certainly would never
have been made if the hypothesis of Dr. Mitchill had in the least
influenced my mind. I thought that the effects might be possibly
depressing and painful, but there were many reasons which induced me
to believe that a single inspiration of a gas apparently possessing
no immediate action on the irritable fibre, could neither destroy or
materially injure the powers of life.
On April 11th, I made the first inspiration of pure nitrous oxide;
it passed through the bronchia without stimulating the glottis, and
produced no uneasy feeling in the lungs.
The result of this experiment, proved that the gas was respirable, and
induced me to believe that a farther trial of its effects might be made
without danger.
On April 16th, Dr. Kinglake being accidentally present, I breathed
three quarts of nitrous oxide from and into a silk bag for more than
half a minute, without previously closing my nose or exhausting my
lungs.
The first inspirations occasioned a slight degree of giddiness. This
was succeeded by an uncommon sense of fulness of the head, accompanied
with loss of distinct sensation and voluntary power, a feeling
analogous to that produced in the first stage of intoxication; but
unattended by pleasurable sensation. Dr. Kinglake, who felt my pulse,
informed me that it was rendered quicker and fuller.
This trial did not satisfy me with regard to its powers; comparing it
with the former ones I was unable to determine whether the operation
was stimulant or depressing.
I communicated the result to Dr. Beddoes, and on April the 17th, he was
present, when the following experiment was made.
Having previously closed my nostrils and exhausted my lungs, I breathed
four quarts of nitrous oxide from and into a silk bag. The first
feelings were similar to those produced in the last experiment; but
in less than half a minute, the respiration being continued, they
diminished gradually, and were succeeded by a sensation analogous to
gentle pressure on all the muscles, attended by an highly pleasurable
thrilling, particularly in the chest and the extremities. The objects
around me became dazzling and my hearing more acute. Towards the last
inspirations, the thrilling increased, the sense of muscular power
became greater, and at last an irresistible propensity to action was
indulged in; I recollect but indistinctly what followed; I know that my
motions were various and violent.
These effects very soon ceased after respiration. In ten minutes, I had
recovered my natural state of mind. The thrilling in the extremities,
continued longer than the other sensations.[206]
This experiment was made in the morning; no languor or exhaustion was
consequent, my feelings throughout the day were as usual, and I passed
the night in undisturbed repose.
[206] Dr. Beddoes has given some account of this experiment, in his
Notice of some observations made at the Medical Pneumatic Institution.
It was noticed in Mr. Nicholson’s Phil. Journal for May 1799.
The next morning the recollections of the effects of the gas were
very indistinct, and had not remarks written immediately after the
experiment recalled them to my mind, I should have even doubted of
their reality. I was willing indeed to attribute some of the strong
emotion to the enthusiasm, which I supposed must have been necessarily
connected with the perception of agreeable feelings, when I was
prepared to experience painful sensations. Two experiments however,
made in the course of this day, with sceptism, convinced me that the
effects were solely owing to the specific operation of the gas.
In each of them I breathed five quarts of nitrous oxide for rather a
longer time than before. The sensations produced were similar, perhaps
not quite so pleasurable; the muscular motions were much less violent.
Having thus ascertained the powers of the gas, I made many experiments
to ascertain the length of time for which it might be breathed with
safety, its effects on the pulse, and its general effects on the health
when often respired.
I found that I could breathe nine quarts of nitrous oxide for three
minutes, and twelve quarts for rather more than four. I could never
breathe it in any quantity, so long as five minutes. Whenever its
operation was carried to the highest extent, the pleasurable thrilling
at its height about the middle of the experiment, gradually diminished,
the sense of pressure on the muscles was lost; impressions ceased to be
perceived; vivid ideas passed rapidly through the mind, and voluntary
power was altogether destroyed, so that the mouth-piece generally dropt
from my unclosed lips.
Whenever the gas was in a high state of purity, it tasted distinctly
sweet to the tongue and palate, and had an agreeable odor. I often
thought that it produced a feeling somewhat analogous to taste, in
its application to my lungs. In one or two experiments, I perceived a
distinct sense of warmth in my chest.
I never felt from it any thing like oppressive respiration: my
inspirations became deep in proportion as I breathed it longer;
but this phænomenon arose from increased energy of the muscles of
respiration, and from a desire of increasing the pleasurable feelings.
Generally when I breathed from six to seven quarts, muscular motions
were produced to a certain extent; sometimes I manifested my pleasure
by stamping or laughing only; at other times, by dancing round the room
and vociferating.
After the respiration of small doses, the exhilaration generally lasted
for five or six minutes only. In one or two experiments when ten quarts
had been breathed for near four minutes, an exhilaration and a sense of
slight intoxication lasted for two or three hours.
On May 3d. To ascertain whether the gas would accelerate or retard
the progress of sleep, I breathed at about 8 o’clock in the evening,
25 quarts of nitrous oxide, in quantities of six at a time, allowing
but short intervals between each dose. The feelings were much less
pleasurable than usual, and during the consumption of the two last
doses, almost indifferent; indeed the gas was breathed rather too soon
after its production and contained some suspended acid vapour which
stimulated the lungs so as to induce coughing.
After the experiments, for the first time I was somewhat depressed and
debilitated; my propensity to sleep however, came on at the usual hour,
and as usual was indulged in, my repose was sound and unbroken.
Between May and July, I habitually breathed the gas, occasionally three
or four times a day for a week together; at other periods, four or five
times a week only.
The doses were generally from six to nine quarts; their effects
appeared undiminished by habit, and were hardly ever exactly similar.
Sometimes I had the feelings of intense intoxication, attended with but
little pleasure; at other times, sublime emotions connected with highly
vivid ideas; my pulse was generally increased in fulness, but rarely in
velocity.
The general effects of its operation upon my health and state of mind,
are extremely difficult of description; nor can I well discriminate
between its agency and that of other physical and moral causes.
I slept much less than usual, and previous to sleep, my mind was long
occupied by visible imagery. I had a constant desire of action, a
restlessness, and an uneasy feeling about the præcordia analogous to
the sickness of hope.
But perhaps these phænomena in some measure depended on the interest
and labour connected with the experimental investigation relating
to the production of nitrous oxide, by which I was at this time
incessantly occupied.
My appetite was as usual, and my pulse not materially altered.
Sometimes for an hour after the inspiration of the gas, I experienced
a species of mental indolence[207] pleasing rather than otherwise, and
never ending in listlessness.
[207] Mild physical pleasure is perhaps always destructive to action.
Almost all our powerful voluntary actions, arise either from hope,
fear, or desire; and the most powerful from desire, which is an emotion
produced by the coalescence of hope or ideal pleasure with physical
pain.
During the last week in which I breathed it uniformly, I imagined that
I had increased sensibility of touch: my fingers were pained by any
thing rough, and the tooth edge produced from slighter causes than
usual. I was certainly more irritable, and felt more acutely from
trifling circumstances. My bodily strength was rather diminished than
increased.
At the end of July, I left off my habitual course of respiration;
but I continued occasionally to breathe the gas, either for the sake
of enjoyment, or with a view of ascertaining its operation under
particular circumstances.
In one instance, when I had head-ache from indigestion, it was
immediately removed by the effects of a large dose of gas; though it
afterwards returned, but with much less violence. In a second instance,
a slighter degree of head-ache was wholly removed by two doses of gas.
The power of the immediate operation of the gas in removing intense
physical pain, I had a very good opportunity of ascertaining.
In cutting one of the unlucky teeth called dentes sapientiæ, I
experienced an extensive inflammation of the gum, accompanied with
great pain, which equally destroyed the power of repose, and of
consistent action.
On the day when the inflammation was most troublesome, I breathed
three large doses of nitrous oxide. The pain always diminished after
the first four or five inspirations; the thrilling came on as usual,
and uneasiness was for a few minutes, swallowed up in pleasure. As the
former state of mind however returned, the state of organ returned
with it; and I once imagined that the pain was more severe after the
experiment than before.
In August, I made many experiments with a view of ascertaining whether
any analogy existed between the sensible effects of the different gases
which are sooner or later fatal to life when respired, and those of
nitrous oxide.
I respired four quarts of Hydrogene[208] nearly pure produced from
zinc and muriatic acid, for near a minute, my lungs being previously
exhausted and my nostrils carefully closed. The first six or seven
inspirations produced no sensations whatever; in half a minute, I
perceived a disagreeable oppression of the chest, which obliged me to
respire very quickly; this oppression gradually increased, till at last
the pain of suffocation compelled me to leave off breathing. I felt no
giddiness during or after the experiment; my pulse was rendered feebler
and quicker; and a by-stander informed me that towards the last, my
cheeks became purple.
[208] Pure hydrogene has been often respired by different Philosophers,
particularly by Scheele, Fontana, and the adventurous and unfortunate
Rosier.
In a second experiment, when the hydrogene was procured from iron and
diluted sulphuric acid, I was unable to respire it for so long as three
quarters of a minute; a transient giddiness and muscular debility
were produced, the pulse was rendered very feeble, and the pain of
suffocation was greater than before.
I breathed three quarts of Nitrogene mingled with a very small portion
of carbonic acid, for near a minute. It produced no alteration in
my sensations for the first twenty seconds; then the painful sense
of suffocation gradually came on, and increased rapidly in the
last quarter of the minute, so as to oblige me to desist from the
experiment. My pulse was rendered feebler and quicker. I felt no
affection whatever in the head.
Mr. Watt’s observations on the respiration of diluted Hydrocarbonate
by men, and Dr. Beddoes’s experiments on the destruction of animals by
pure hydrocarbonate, proved that its effects were highly deleterious.
As it destroyed life apparently by rendering the muscular fibre
inirritable without producing any previous excitement, I was anxious
to compare its sensible effects with those of nitrous oxide, which at
this time I believed to destroy life by producing the highest possible
excitement, ending in læsion of organisation.
In the first experiment, I breathed for near a minute, three quarts of
hydrocarbonate mingled with nearly two quarts of atmospheric air.[209]
It produced a slight giddiness and pain in the head, and a momentary
loss of voluntary power: my pulse was rendered much quicker and
feebler. These effects however, went off in five minutes, and I had no
return of giddiness.
[209] I believe it had never been breathed before by any individual, in
a state so little diluted.
Emboldened by this trial, in which the feelings were not unlike those
I experienced in the first experiments on nitrous oxide, I resolved to
breathe pure hydrocarbonate.
For this purpose, I introduced into a silk bag, four quarts of gas
nearly pure, which was carefully produced from the decomposition of
water by charcoal an hour before, and which had a very strong and
disagreeable smell.
My friend, Mr. James Tobin, Junr. being present, after a forced
exhaustion of my lungs, the nose being accurately closed, I made
three inspirations and expirations of the hydrocarbonate. The first
inspiration produced a sort of numbness and loss of feeling in the
chest and about the pectoral muscles. After the second inspiration,
I lost all power of perceiving external things, and had no distinct
sensation except a terrible oppression on the chest. During the
third expiration, this feeling disappeared, I seemed sinking into
annihilation, and had just power enough to drop the mouth-piece from
my unclosed lips. A short interval must have passed during which I
respired common air, before the objects about me were distinguishable.
On recollecting myself, I faintly articulated, “_I do not think I shall
die_.” Putting my finger on the wrist, I found my pulse thread-like and
beating with excessive quickness.
In less than a minute, I was able to walk, and the painful oppression
on the chest directed me to the open air.
After making a few steps which carried me to the garden, my head
became giddy, my knees trembled, and I had just sufficient voluntary
power to throw myself on the grass. Here the painful feeling of the
chest increased with such violence as to threaten suffocation. At
this moment, I asked for some nitrous oxide. Mr. Dwyer brought me a
mixture of oxygene and nitrous oxide. I breathed this for a minute,
and _believed_ myself relieved. In five minutes, the painful feelings
began gradually to diminish. In an hour they had nearly disappeared,
and I felt only excessive weakness and a slight swimming of the head.
My voice was very feeble and indistinct. This was at two o’clock in the
afternoon.
I afterwards walked slowly for about half an hour, with Mr. Tobin,
Junr. and on my return, was so much stronger and better, as to believe
that the effects of the gas had disappeared; though my pulse was 120
and very feeble. I continued without pain for near three quarters of
an hour; when the giddiness returned with such violence as to oblige
me to lie on the bed; it was accompanied with nausea, loss of memory,
and deficient sensation. In about an hour and half, the giddiness went
off, and was succeeded by an excruciating pain in the forehead and
between the eyes, with transient pains in the chest and extremities.
Towards night these affections gradually diminished. At ten,[210] no
disagreeable feeling except weakness remained. I slept sound, and
awoke in the morning very feeble and very hungry. No recurrence of the
symptoms took place, and I had nearly recovered my strength by the
evening.
I have been minute in the account of this experiment because it
proves, that hydrocarbonate acts as a sedative, i. e. that it
produces diminution of vital action, and debility, without previously
exciting. There is every reason to believe, that if I had taken four
or five inspirations instead of three, they would have destroyed life
immediately without producing any painful sensation. Perhaps most of
the uneasy feelings after the experiment, were connected with the
return of the healthy condition of organs.[211]
[210] I ought to observe, that between eight and ten, I took by the
advice of Dr. Beddoes, two or three doses of diluted nitric acid.
[211] By whatever cause the exhaustion of organs is produced, pain
is almost uniformly connected with their returning health. Pain is
rarely ever perceived in limbs debilitated by fatigue till after they
have been for some hours at rest. Pain is uniformly connected with the
recovery from the debility induced by typhus, often with the recovery
from that produced by the stimulation of opium and alcohol.
About a week after this experiment, I attempted to respire Carbonic
acid, not being at the time acquainted with the experiments of Rosier.
I introduced into a silk bag four quarts of well washed carbonic acid
produced from carbonate of ammoniac[212] by heat, and after a compleat
voluntary exhaustion of my lungs, attempted to inspire it. It tasted
strongly acid in the mouth and fauces, and produced a sense of burning
at the top of the uvula. In vain I made powerful voluntary efforts
to draw it into the windpipe; at the moment that the epiglottis was
raised a little, a painful stimulation was induced, so as to close
it spasmodically on the glottis; and thus in repeated trials I was
prevented from taking a single particle of carbonic acid into my lungs.
[212] Carbonic acid is produced in this way in a high state of purity,
and with great readiness.
I tried to breathe a mixture of two quarts of common air and three of
carbonic acid, without success; it stimulated the epiglottis nearly in
the same manner as pure carbonic acid, and was perfectly non-respirable.
I found that a mixture of three quarts of carbonic acid with seven of
common air was respirable, I breathed it for near a minute. At the
time, it produced a slight degree of giddiness, and an inclination to
sleep. These effects however, very rapidly disappeared after I had
ceased to breathe,[213] and no other affections followed.
[213] Carbonic acid possesses no action on arterial blood. Hence
perhaps, its slight effects when breathed mingled with large quantities
of common air. Its effects are very marked upon venous blood! If
it were thrown forcibly into the lungs of animals, the momentary
application of it to the pulmonary venous blood would probably destroy
life.
During the course of experiments on nitrous oxide, I several times
breathed Oxygene procured from manganese by heat, for from three to
five minutes.
In respiring eight or ten quarts; for the first two or three minutes
I could perceive no effects. Towards the end, even when I breathed
very slowly, my respiration became oppressed, and I felt a sensation
analogous to that produced by the want of fresh air; though but little
of the oxygene had been consumed.
In one experiment when I breathed from and into a bag containing 20
quarts of oxygene for near six minutes; Dr. Kinglake felt my pulse,
and found it not altered in velocity, but rather harder than before. I
perceived no effects but those of oppression on the chest[214].
[214] In a conversation with Mr. Watt, relating to the powers of gases,
that excellent philosopher told me he had for some time entertained
a suspicion, that the effects attributed to oxygene produced from
manganese by heat, in some measure depended upon nitrous acid suspended
in the gas, formed during ignition by the union of some of the oxygene
of the manganese with nitrogene likewise condensed in it.
In the course of experiments on nitrous acid, detailed in Research
I. made in September, October, and December, 1799, I several times
experienced a severe oppression on the chest and difficulty of
respiration, not unanalogous to that produced by oxygene, but much more
violent, from breathing an atmosphere loaded with nitrous acid vapour.
This fact seemed to confirm Mr. Watt’s suspicion. I confess, however,
that I have never been able to detect any smell of nitrous acid, either
by means of my own organs or those of others, during the production
of oxygene; when the gas is suffered to pass into the atmosphere. The
oxygene breathed in the experiments detailed in the text, had been for
some days in contact with water.
Having observed in my experiments upon venous blood, that Nitrous gas
rendered that fluid of a purple tinge, very like the color generated
in it by nitrous oxide; and finding no painful effects produced by
the application of nitrous gas to the bare muscular fibre, I began to
imagine that this gas might be breathed with impunity, provided it were
possible in any way to free the lungs of common air before inspiration,
so as to prevent the formation of nitrous acid.
On this supposition, during a fit of enthusiasm produced by the
respiration of nitrous oxide, I resolved to endeavour to breathe
Nitrous gas.
114 cubic inches of nitrous gas were introduced into the large
mercurial airholder; two small silk bags of the capacity of seven
quarts were filled with nitrous oxide.
After a forced exhaustion of my lungs, my nose being accurately closed,
I made three inspirations and expirations of nitrous oxide in one
of the bags, to free my lungs as much as possible from atmospheric
oxygene; then, after a full expiration of the nitrous oxide, I
transferred my mouth from the mouth-piece of the bag to that of the
airholder, and turning the stop-cock, attempted to inspire the nitrous
gas.—In passing through my mouth and fauces, it tasted astringent and
highly disagreeable; it occasioned a sense of burning in the throat,
and produced a spasm of the epiglottis so painful as to oblige me to
desist instantly from attempts to inspire it. After moving my lips from
the mouth-piece, when I opened them to inspire common air, aëriform
nitrous acid was instantly formed in my mouth, which burnt the tongue
and palate, injured the teeth, and produced an inflammation of the
mucous membrane which lasted for some hours.
As after the respiration of nitrous oxide in the experiments in the
last Research, a small portion of the residual atmospheric air remained
in the lungs, mingled with the gas, after forced expiration; it is
most probable that a minute portion of nitrous acid was formed in this
experiment, when the nitrous gas was taken into the mouth and fauces,
which might produce its stimulating properties. If so, perhaps I owe my
life to the circumstance; for supposing I had taken an inspiration of
nitrous gas, and even that it had produced no positive effects, it is
highly improbable, that by breathing nitrous oxide, I should have freed
my lungs from it, so as to have prevented the formation of nitrous acid
when I again inspired common air. I never design again to attempt so
rash an experiment.
In the beginning of September I often respired nitrous oxide mingled
with different proportions of common air or oxygene. The effects
produced by the diluted gas were much less violent than those produced
by pure nitrous oxide. They were generally pleasant: the thrilling was
not often perceived, but a sense of exhilaration was almost constant.
Between September and the end of October, I made but few experiments
on respiration, almost the whole of my time being devoted to chemical
experiments on the production and analysis of nitrous oxide.
At this period my health being somewhat injured by the constant labour
of experimenting, and the perpetual inhalation of the acid vapours of
the laboratory, I went into Cornwall; where new associations of ideas
and feelings, common exercise, a pure atmosphere, luxurious diet and
moderate indulgence in wine, in a month restored me to health and vigor.
Nov. 27th. Immediately after my return, being fatigued by a long
journey, I respired nine quarts of nitrous oxide, having been precisely
thirty-three days without breathing any. The feelings were different
from those I had experienced in former experiments. After the first
six or seven inspirations, I gradually began to lose the perception
of external things, and a vivid and intense recollection of some
former experiments passed through my mind, so that I called out “_what
an amazing concatenation of ideas!_” I had no pleasurable feeling
whatever, I used no muscular motion, nor did I feel any disposition
to it; after a minute, when I made the note of the experiment, all
the uncommon sensations had vanished; they were succeeded by a slight
soreness in one of the arms and in the leg: in three minutes these
affections likewise disappeared.
From this experiment I was inclined to suppose that my newly acquired
health had diminished my susceptibility to the effects of the gas.
About ten days after, however, I had an opportunity of proving the
fallacy of this supposition.
Immediately after a journey of 126 miles, in which I had no sleep the
preceding night, being much exhausted, I respired seven quarts of gas
for near three minutes. It produced the usual pleasurable effects,
and slight muscular motion. I continued exhilarated for some minutes
afterwards: but in half an hour found myself neither more or less
exhausted than before the experiment. I had a great propensity to sleep.
I repeated the experiment four or five times in the following week,
with similar effects. My susceptibility was certainly not diminished. I
even thought that I was more affected than formerly by equal doses.
Though, except in one instance, when indeed the gas was impure, I had
experienced no decisive exhaustion after the excitement from nitrous
oxide, yet still I was far from being satisfied that it was unanalogous
to stimulants in general.—No experiment had been made in which the
excitement from nitrous oxide had been kept up for so great a length of
time and carried to so great an extent as that in which it is uniformly
succeeded by excessive debility under the agency of other powers.
It occurred to me, that supposing nitrous oxide to be a stimulant
of the common class, it would follow that the debility produced in
consequence of excessive stimulation by a known agent, ought to be
_increased_ after excitement from nitrous oxide.[215]
[215] In the same manner as the debility from intoxication by two
bottles of wine is increased by a third.
To ascertain whether this was the case, I made on December 23d, at
four P. M. the following experiment. I drank a bottle of wine in
large draughts in less than eight minutes. Whilst I was drinking,
I perceived a sense of fulness in the head, and throbbing of the
arteries, not unanalogous to that produced in the first stage of
nitrous oxide excitement. After I had finished the bottle, this fulness
increased, the objects around me became dazzling, the power of distinct
articulation was lost, and I was unable to walk steadily. At this
moment the sensations were rather pleasurable than otherwise, the sense
of fulness in the head soon however increased so as to become painful,
and in less than an hour I sunk into a state of insensibility.[216]
[216] I ought to observe that my usual drink is water, that I had
been little accustomed to take wine or spirits, and had never been
compleatly intoxicated but once before in the course of my life. This
will account for the powerful effects of a single bottle of wine. In
this situation I must have remained for two hours or two hours and half.
I was awakened by head-ache and painful nausea. The nausea continued
even after the contents of the stomach had been ejected. The pain in
the head every minute increased; I was neither feverish or thirsty; my
bodily and mental debility were excessive, and the pulse feeble and
quick.
In this state I breathed for near a minute and half five quarts of gas,
which was brought to me by the operator for nitrous oxide; but as it
produced no sensations whatever, and apparently rather increased my
debility, I am almost convinced that it was from some accident, either
common air, or very impure nitrous oxide.
Immediately after this trial, I respired 12 quarts of oxygene for near
four minutes. It produced no alteration in my sensations at the time;
but immediately after I imagined that I was a little exhilarated.
The head-ache and debility still however continuing with violence, I
examined some nitrous oxide which had been prepared in the morning, and
finding it very pure, respired seven quarts of it for two minutes and
half.
I was unconscious of head-ache after the third inspiration; the usual
pleasurable thrilling was produced, voluntary power was destroyed, and
vivid ideas rapidly passed through my mind; I made strides across the
room, and continued for some minutes much exhilarated. Immediately
after the exhilaration had disappeared, I felt a slight return of the
head-ache; it was connected with transient nausea. After two minutes,
when a small quantity of acidified wine had been thrown from the
stomach, both the nausea and head-ache disappeared; but languor and
depression not very different in degree from those existing before the
experiment, succeeded. They however, gradually went off before bed
time. I slept sound the whole of the night except for a few minutes,
during which I was kept awake by a trifling head-ache. In the morning,
I had no longer any debility. No head-ache or giddiness came on after I
had arisen, and my appetite was very great.
This experiment proved, that debility from intoxication was not
increased by excitement from nitrous oxide. The head-ache and
depression, it is probable, would have continued longer if it had not
been administered. Is it not likely that the slight nausea following
the effects of the gas was produced by new excitability given to the
stomach?
To ascertain with certainty, whether the most extensive action of
nitrous oxide compatible with life, was capable of producing debility,
I resolved to breathe the gas for such a time and in such quantities,
as to produce excitement equal in duration and superior in intensity to
that occasioned by high intoxication from opium or alcohol.
To habituate myself to the excitement, and to carry it on gradually.
On December 26th, I was inclosed in an air-tight breathing-box,[217]
of the capacity of about 9 cubic feet and half, in the presence of Dr.
Kinglake.
After I had taken a situation in which I could by means of a curved
thermometer inserted under the arm, and a stop-watch, ascertain the
alterations in my pulse and animal heat, 20 quarts of nitrous oxide
were thrown into the box.
For three minutes I experienced no alteration in my sensations, though
immediately after the introduction of the nitrous oxide the smell and
taste of it were very evident.[218]
[217] The plan of this box was communicated by Mr. Watt. An account of
it will be detailed in the _Researches_.
[218] The nitrous oxide was too diluted to act much; it was mingled
with near 32 times its bulk of atmospheric air.
In four minutes I began to feel a slight glow in the cheeks, and a
generally diffused warmth over the chest, though the temperature of the
box was not quite 50°. I had neglected to feel my pulse before I went
in; at this time it was 104 and hard, the animal heat was 98°. In ten
minutes the animal heat was near 99°, in a quarter of an hour 99.5°,
when the pulse was 102, and fuller than before.
At this period 20 quarts more of nitrous oxide were thrown into the
box, and well-mingled with the mass of air by agitation.
In 25 minutes the animal heat was 100°, pulse 124. In 30 minutes, 20
quarts more of gas were introduced.
My sensations were now pleasant; I had a generally diffused warmth
without the slightest moisture of the skin, a sense of exhilaration
similar to that produced by a small dose of wine, and a disposition to
muscular motion and to merriment.
In three quarters of an hour the pulse was 104, and animal heat not
99,5°, the temperature of the chamber was 64°. The pleasurable feelings
continued to increase, the pulse became fuller and slower, till in
about an hour it was 88, when the animal heat was 99°.
20 quarts more of air were admitted. I had now a great disposition to
laugh, luminous points seemed frequently to pass before my eyes, my
hearing was certainly more acute and I felt a pleasant lightness and
power of exertion in my muscles. In a short time the symptoms became
stationary; breathing was rather oppressed, and on account of the great
desire of action, rest was painful.