water; and if we disturb the mud beneath with a pole or rake, many thousands of such bubbles will quickly

appear.

The Chemist has devised means similar in principle to those described, for collecting this exhalation, and upon analysis, he discovers it to be neither atmospheric air nor oxygen, but a gas composed of Carbon and Hydrogen, combustible, and burning with a yellow flame; in these respects it is identical with the "Fire damp" of coal mines, and closely analogous to the "Gas" obtained from coal for the purpose of artificial illumination; and therefore to denote that it contains the above elements, it is called "Carburetted Hydrogen."

The Chemist presumes this gaseous compound to be formed in stagnant water by the spontaneous decay or decomposition of its vegetable productions; and when it is kindled, either by lightning, or some unknown agent, it is probably the cause of the light that so frequently appears during Summer and Autumnal evenings, flickering and dancing over the surface of boggy and marshy soils, presenting the phenomenon called Ignis fatuus," or popularly the "Jack-o'-Lantern," or the "Will-o'-the-Wisp."

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In this country, the beautiful spontaneous light of the "glow-worm," and that of the common "hundred legged worm" when irritated, are both popularly known; but in hotter climates the "lantern fly" and fire fly" exhibit this luminous appearance in a degree yet more remarkable; nothing certain has been ascertained re

garding the cause of the phenomenon, it is probably referrible to the slow combustion of Phosphorus which these insects have the power of secreting; as this light may be imitated by gently rubbing the tip of “phosphoric paste" of a "Lucifer match" in the dark.

The decayed or "touch-wood" of old forest trees may be often observed to emit a pale light spontaneously; also some kinds of fungi, if struck, as by the foot in walking over them at night; some flowers, as the tuberose, nasturtium, and marigold, occasionally present flashes of light towards the close of warm evenings.

The chemist has not discovered the cause of these extraordinary phenomena, and therefore for want of knowledge contents himself with denoting them under the general title of "Phosphorescent" substances."

Several animal substances are thus "Phosphorescent" when deprived of vitality, and long before their putrefaction commences; and of these the flesh of the carp, tench, herring, sole, crab, and lobster, are the most remarkable; this phenomenon of luminosity is seldom presented by the dead flesh of quadrupeds, and never by that of birds under any circumstances of putrefaction.

Water has frequently engaged our attention as a most active agent in promoting not only the growth, but when that ceases, the decay of vegetation; and this is especially the case when the element Nitrogen enters into the constitution of organized struc

tures.

"The doctrine of the proper application of manures from organized substances, offers an illustration of an important part of the economy of Nature, and of the happy order in which it is arranged.

"The death and decay of animal substances tend to resolve organized forms into chemical constituents; and the pernicious effluvia disengaged in the process, seem to point out the propriety of burying them in the soil, where they are fitted to become the food of vegetables.

"The fermentation and putrefaction of organized substances in the free atmosphere, are noxious processes; beneath the surface of the ground they are salutary operations.

"In this case, the food of plants is prepared where it can be used; and that which would offend the senses and injure the health, if exposed, is converted by gradual processes into forms of beauty and of usefulness; the fetid gas is rendered a constituent of the aroma of the flower, and what might be poison, becomes nourishment to animals and to man."

It has long been familiar to physicians, that there is produced by wet lands, or by marshes and swamps, a poisonous and aëriform substance, the cause not only of ordinary fevers, but of intermittents; and to this unknown agent of disease the term "marsh-miasma" has been applied; nor is such knowledge confined to physic; throughout the world it is a fact known to the vulgar and even to the less enlightened nations.

It is familiar to the rural inhabitants of Lincolnshire

and Essex, who refer to the fens of these districts as the source of the agues under which they so commonly suffer; it is known to the rural inhabitants of certain districts of France, Holland, and Italy, in this last country more particularly, as "malaria;" it is also known to the uncivilized negroes of Africa.

The fairest portions of Italy are a prey to this invisible enemy "malaria;" the fragrant breezes are poison, the dews of its summer evenings are death, the banks of its refreshing streams, its rich and flowery meadows, the borders of its glassy lakes, the luxuriant plains of its overflowing agriculture, the valleys where its shrubs regale the eye and perfume the air, are the appointed regions of this "malaria.”

Death here walks hand in hand with the resources of life, sparing none; the labourer reaps his harvest but to die; or, he wanders amid the luxuriance of vegetation a sufferer from his cradle to his grave; aged even in childhood, and laying down in misery that life which was but one disease. He is even driven from some of the richest portions of this fertile, yet unhappy country; and the traveller contemplates at a distance, deserts, but deserts of vegetable wealth which man dare not approach or he dies.

Such is the picture of the noxious influence of these exhalations, which the Creator for some inscrutable purpose has ordained to reign in certain districts of this fair world.

This "marsh miasma," or " malaria," often exerts its baneful power upon the husbandman in our country,

at .a time when his bodily strength and activity are most demanded for the pursuit of his labours; and therefore he devises all possible means for arresting its sway-cutting down the vegetation, removing the putrefying and corrupting mass,-sedulously draining off the stagnant water of marshes;-and thus he can occasionally improve the salubrity of districts within certain limits; but some districts are so extensive and so contaminated, as to defy amelioration by the utmost exertions of human foresight and labour, and they remain proverbially insalubrious.

In crowded cities and towns, where the buildings are imperfectly ventilated, badly drained, and scantily supplied with water, if animal or vegetable offal be suffered to accumulate through indolence or neglect, and thus putrefy in the heat of Summer or Autumn, infectious or contagious matters are inevitably evolved or produced, and occasionally display their deadly powers in all the horrors of plague and pestilence.

The Almighty has not permitted the Chemist to discover the nature or the elements of such attenuated exhalations, they elude all detection; for if he take a volume of stagnant air from the foul "plague ward" of an Egyptian hospital, where crowds of livid and cadaverous beings are hourly stricken with the agonies of death;—his analysis will prove it to contain the exact proportions by weight and by measure of elements and compounds, as those contained in an equal volume of a balmy breeze taken from a free and open English valley, where all are smiling with the ines