gree; viz. that of being imbibed by water.
But, indeed, all kinds of air, common air itself not excepted, are
capable of being imbibed by water in some degree.

Some may think the terms acid and alkaline _vapour_ more proper than
acid and alkaline _air_. But the term _vapour_ having always been
applied to elastic matters capable of being condensed in the temperature
of the atmosphere, especially the vapour of water, it seems harsh to
apply it to any elastic substance, which at the same time that it is as
transparent as the air we breathe, is no more affected by cold than it
is.

As my former papers were immediately translated into several foreign
languages, I may presume that this treatise, having a better title to
it, will be translated also; and, upon this presumption, I cannot help
expressing a wish, that it may be done by persons who have a competent
knowledge of _subject_, as well as of the _English language_. The
mistakes made by some foreigners, have induced me to give this caution.

_London, Feb._
_1774._

ADVERTISEMENT.

The _weights_ mentioned in the course of this treatise are _Troy_, and
what is called _an ounce measure of air_, is the space occupied by an
ounce weight of water, which is equal to 480 grains, and is, therefore,
almost two _cubic inches_ of water; for one cubic inch weighs 254
grains.

FOOTNOTES:

[1] See Sir John Pringle's _Discourse on the different kinds of air_, p.
29, which, if it became me to do it, I would recommend to the reader, as
containing a just and elegant account of the several discoveries that
have been successively made, relating to the subject of this treatise.

THE CONTENTS.

THE INTRODUCTION.

Section I. _A general view of PRECEDING DISCOVERIES relating to
AIR_ Page 1

Sect. II. _An Account of the APPARATUS with which the following
Experiments were made_ 6

PART I.

_Experiments and Observations made in, and before the Year 1772._ 23

Sect. I. _Of FIXED AIR_ 25

Sect. II. _Of AIR in which a CANDLE, or BRIMSTONE, has burned out_ 43

Sect. III. _Of INFLAMMABLE AIR_ 55

Sect. IV. _Of AIR infected with ANIMAL RESPIRATION, or PUTREFACTION_ 70

Sect. V. _Of AIR in which a mixture of BRIMSTONE and FILINGS of
IRON has stood_