In consequence of the discovery of the respirability and extraordinary
effects of nitrous oxide, or the dephlogisticated nitrous gas of Dr.
Priestley, made in April 1799, in a manner to be particularly described
hereafter,[1] I was induced to carry on the following investigation
concerning its composition, properties, combinations, and mode of
operation on living beings.
[1] A short account of this discovery has been given in Dr. Beddoes’s
Notice of some Observations made at the Pneumatic Institution, and in
Mr. Nicholson’s Phil. Journal for May and December 1799.
In the course of this investigation, I have met with many difficulties;
some arising from the novel and obscure nature of the subject, and
others from a want of coincidence in the observations of different
experimentalists on the properties and mode of production of the gas.
By extending my researches to the different substances connected
with nitrous oxide; nitrous acid, nitrous gas and ammoniac; and by
multiplying the comparisons of facts, I have succeeded in removing the
greater number of those difficulties, and have been enabled to give a
tolerably clear history of the combinations of oxygene and nitrogene.
By employing both analysis and synthesis whenever these methods were
equally applicable, and comparing experiments made under different
circumstances, I have endeavoured to guard against sources of error;
but I cannot flatter myself that I have altogether avoided them. The
physical sciences are almost wholly dependant on the minute observation
and comparison of properties of things not immediately obvious to the
senses; and from the difficulty of discovering every possible mode of
examination, and from the modification of perceptions by the state
of feeling, it appears nearly impossible that all the relations of
a series of phænomena can be discovered by a single investigation,
particularly when these relations are complicated, and many of the
agents unknown. Fortunately for the active and progressive nature
of the human mind, even experimental research is only a method of
approximation to truth.
In the arrangement of facts, I have been guided as much as possible by
obvious and simple analogies only. Hence I have seldom entered into
theoretical discussions, particularly concerning light, heat, and other
agents, which are known only by isolated effects.
Early experience has taught me the folly of hasty generalisation. We
are ignorant of the laws of corpuscular motion; and an immense mass of
minute observations concerning the more complicated chemical changes
must be collected, probably before we shall be able to ascertain even
whether we are capable of discovering them. Chemistry in its present
state, is simply a partial history of phænomena, consisting of many
series more or less extensive of accurately connected facts.
With the most important of these series, the arrangement of the
combinations of oxygene or the antiphlogistic theory discovered by
Lavoisier, the chemical details in this work are capable of being
connected.
In the present state of science, it will be unnecessary to enter into
discussions concerning the importance of investigations relating to
the properties of physiological agents, and the changes effected in
them during their operation. By means of such investigations, we arrive
nearer towards that point from which we shall be able to view what is
within the reach of discovery, and what must for ever remain unknown to
us, in the phænomena of organic life. They are of immediate utility, by
enabling us to extend our analogies so as to investigate the properties
of untried substances, with greater accuracy and probability of
success.
The first Research in this work chiefly relates to the production
of nitrous oxide and the analysis of nitrous gas and nitrous acid.
In this there is little that can be properly called mine; and if by
repeating the experiments of other chemists, I have sometimes been able
to make more minute observations concerning phænomena, and to draw
different conclusions, it is wholly owing to the use I have made of
the instruments of investigation discovered by the illustrious fathers
of chemical philosophy,[2] and so successfully applied by them to the
discovery of truth.
[2] Cavendish, Priestley, Black, Lavoisier, Scheele, Kirwan, Guyton,
Berthollet, &c.
In the second Research the combinations and composition of nitrous
oxide are investigated, and an account given of its decomposition by
most of the combustible bodies.
The third Research contains observations on the action of nitrous
oxide upon animals, and an investigation of the changes effected in it
by respiration.
In the fourth Research the history of the respirability and
extraordinary effects of nitrous oxide is given, with details of
experiments on its powers made by different individuals.
I cannot close this introduction, without acknowledging my obligations
to Dr. Beddoes. In the conception of many of the following experiments,
I have been aided by his conversation and advice. They were executed
in an Institution which owes its existence to his benevolent and
philosophic exertions.
_Dowry-Square, Hotwells, Bristol._
_June 25th, 1800._