THIS little work is to a great extent the result of my own observations, which have spread over a considerable number of years; but I have also availed myself largely of the labours of others, in order to make it more complete, and more useful; for, as Benjamin Franklin said, "Knowledge is only valuable in proportion as it can be rendered useful to mankind."

I owe to my excellent father, to whom I dedicated one of my former works, everything that could foster the prosecution of travel and research, and, though I have not taken full advantage of the excessive liberality which he accorded to all his children, and cannot recall his memory without acknowledging the immense debt of gratitude with which it is associated, yet I trust that my numerous writings will prove "useful to mankind" for many years to come. However, his kindness and foresight have enabled me to devote my life to scientific pursuits, music, and literature, thus doing all he could to make it a life of happiness and contentment in spite of the sorrows and afflictions to which we are all subject in this world, and I have striven to make it also a useful life.

The present volume contains the results of the latest

discoveries connected with the vast aërial ocean which encircles the Earth; the physical and chemical proper ties of the air; its geological history as far as we car trace it into the remotest ages of the past, and the useful deductions that can be drawn from all these facts.

My discovery of the origin of atmospheric oxygen made known in a series of papers published from 1893 to 1895 (Chemical News, London; Comptes-rendus, Paris) and the curious results of that discovery, induced me to write this book, as so much interest is now taken in the subject, in all parts of the world.

In the Philosophical Magazine for September and October 1900 are two papers by Mr. John Stevenson, M.A., communicated by Professor G. F. FitzGerald, F.R.S., on the chemical and geological history of the atmosphere, in which allusion is most indulgently made to "Dr. Phipson's beautiful and interesting experiments," and in which Lord Kelvin's views are discussed. After a very long and interesting discussion, Mr. Stevenson confirms my opinion, declaring that "there was a time when there was no free oxygen upon the Earth," and also that "our present supply of free oxygen has been all produced by the action of sunlight on vegetation," which is precisely what my experiments and observations have established.

CASA MIA, PUTNEY, LONDON.

RESEARCHES ON

THE EARTH'S ATMOSPHERE.

INTRODUCTION.

The Science of the Atmosphere-Its Numerous and Important Applications-Origin of Modern Chemistry-The Theory of Combustion-History of the Chemical Composition of the Air-Discovery of the Barometer.

THE Science of the Atmosphere embraces not only the whole domain of Meteorology-the laws that determine the distribution of temperature, the cause of winds and cyclonic storms, the formation of fogs, clouds, dew, rain, snow, and hail, luminous manifestations due to electricity, the phenomena of thunderstorms, ignis fatuus, and fire-springs, phosphorescent glows, mirage, halos, aurora, waterspouts, avalanches, and glacier movement, sand and dust storms, etc.-but, also, the realms of Physical Geography, Geology, Chemistry, and Physiology—the destructive action of the air upon the Earth's surface, by its physical or mechanical action, and by its chemical action; the phenomena of respiration in Plants and Animals, and its important consequences.

A

Hence the study of the Atmosphere includes certai branches of Medicine, antiseptic Surgery, and Hygien establishing the laws of Climatology, by which th practitioner is guided in the choice of residence fo invalids. It also enables him to effect the promotio of health, and prevention of disease, by the detectio of impure, noxious air, and by applying the art o rendering it wholesome.

Moreover, it embraces, also, certain practical portion of Astronomy and Physics-the laws of reflection, re fraction, interference, absorption, pressure, electric con dition, and magnetism.

It is, indeed, a vast field of inquiry, and one that is practically inexhaustible; full of surprises inciting to research, and leading to endless useful applications.

The Chemist and the Naturalist, the Astronomer and the Physician, are alike interested in acquiring the most perfect knowledge of the nature and phenomena of our atmosphere, which knowledge forms the basis of the greater portion of the sciences, and promotes the prosperity of the human race.

The history of Chemistry-the dawn of scientific chemistry-is intimately connected with this subject, for modern Chemistry, with all its marvels of industry and invention, may be said to date from the discovery of oxygen. The advancement of the mechanical arts, promoted by the discovery of the barometer and its laws, is no less dependent upon an intimate acquaintance with the properties of that vast aërial envelope which encircles our globe, and is generally supposed

The knowledge of the chemical composition of the air is closely connected with the phenomenon of combustion the most wonderful of all the phenomena of Nature the theory of which forms the basis of modern science, and governs its useful applications to the wants of man. The ancients imagined a certain elementary body called fire, which possessed the property of devouring other bodies and converting them into itself. According to this view, which is still held by our domestic servants, when we set fire to a grate of coals we bring a small portion of the element fire which. immediately begins to devour the coal and convert it also into fire. Whatever part of the coal is not fit to be this food is left behind in the form of ashes.

It was in 1665 that the celebrated English philosopher Dr. Hooke (Micrographia, p. 103) first found that there exists in the Atmosphere. a certain substance which is like that fixed in saltpetre. The French physician Jean Rey held a somewhat similar opinion thirty-five years previously.1 In 1675 Hooke's opinion was adopted and extended by Mayow, a young man of Oxford, who published a pamphlet on the subject: De sal-nitro et Spiritus nitro-aereo, which is now celebrated in the annals of Science.

1 But about a century before this, the physician to Henri IV., Joseph Duchesne, called Quercitanus, a disciple of Paracelsus, who was also the inventor of laudanum, and the discoverer of the gluten of wheat flour, got the first glimpse of nitrogen. It was about the year 1573 he said that "saltpetre contains an air which extinguishes