Table of Contents
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 105 Sect. VI. Of Nitrous Air 108 Sect. VII. Of Air infected with the fumes of burning Charcoal 129 Sect. VIII. Of the effect of the calcination of Metals, and of the effluvia of Paint made with White-Lead and Oil, on Air 133 Sect. IX. Of Marine Acid Air 143 Sect. X. Miscellaneous Observations 154 PART II. Experiments and Observations made in the Year 1773, and the Beginning of 1774. Sect. I. Observations on Alkaline Air 163 Sect. II. Of common Air diminished, and made noxious by various processes 177 Sect. III. Of Nitrous Air 203 Sect. IV. Of Marine Acid Air 229 Sect. V. Of Inflammable Air 242 Sect. VI. Of Fixed Air 248 Sect. VII. Miscellaneous Experiments 252 Sect. VIII. Queries, Speculations, and Hints 258 The APPENDIX. Number I. Experiments made by Mr. Hey to prove that there is no Oil of Vitriol in water impregnated with Fixed Air 288 Number II. A Letter from Mr. Hey to Dr. Priestley, concerning the effects of fixed Air applied by way of Clyster 292 Number III. Observations on the Medicinal Uses of Fixed Air. By Thomas Percival, M. D. Fellow of the Royal Society, and of the Society of Antiquaries in London 300 Number IV. Extract of a Letter from William Falconer, M. D. of Bath 314 Number V. Extract of a Letter from Mr. William Bewley, of Great Massingham, Norfolk 317 Num. VI. A Letter from Dr. Franklin 321 Number VII. Extract of Letter from Mr. Henry of Manchester 323
THE INTRODUCTION.
SECTION I.
A general view of preceding discoveries relating to air.
For the better understanding of the experiments and observations on different kinds of air contained in this treatise, it will be useful to those who are not acquainted with the history of this branch of natural philosophy, to be informed of those facts which had been discovered by others, before I turned my thoughts to the subject; which suggested, and by the help of which I was enabled to pursue, my inquiries. Let it be observed, however, that I do not profess to recite in this place all that had been discovered concerning air, but only those discoveries the knowledge of which is necessary, in order to understand what I have done myself; so that any person who is only acquainted with the general principles of natural philosophy, may be able to read this treatise, and, with proper attention, to understand every part of it.
That the air which constitutes the atmosphere in which we live has weight, and that it is elastic, or consists of a compressible and dilatable fluid, were some of the earliest discoveries that were made after the dawning of philosophy in this western part of the world.
That elastic fluids, differing essentially from the air of the atmosphere, but agreeing with it in the properties of weight, elasticity, and transparency, might be generated from solid substances, was discovered by Mr. Boyle, though two remarkable kinds of factitious air, at least the effects of them, had been known long before to all miners. One of these is heavier than common air. It lies at the bottom of pits, extinguishes candles, and kills animals that breathe it, on which account it had obtained the name of the choke damp. The other is lighter than common air, taking its place near the roofs of subterraneous places, and because it is liable to take fire, and explode, like gunpowder, it had been called the fire damp. The word damp signifies vapour or exhalation in the German and Saxon language.
Though the former of these kinds of air had been known to be noxious, the latter I believe had not been discovered to be so, having always been found in its natural state, so much diluted with common air, as to be breathed with safety. Air of the former kind, besides having been discovered in various caverns, particularly the grotta del Cane in Italy, had also been observed on the surface of fermenting liquors, and had been called gas (which is the same with geist, or spirit) by Van Helmont, and other German chymists; but afterwards it obtained the name of fixed air, especially after it had been discovered by Dr. Black of Edinburgh to exist, in a fixed state, in alkaline salts, chalk, and other calcareous substances.
This excellent philosopher discovered that it is the presence of the fixed air in these substances that renders them mild, and that when they are deprived of it, by the force of fire, or any other process, they are in that state which had been called caustic, from their corroding or burning animal and vegetable substances.
Fixed
