jets of brilliant yellow flame, or may be kindled by a slip of lighted paper; how are these produced?

The iron bars becoming heated, conduct heat to the interiors of the lumps of coal, and there causes its decomposition into volatile vapor or gas, which cannot burn for want of air, but at length accumulates in sufficient quantity and force to break through the weakest parts of the coals, and issue into the air, and then it either escapes unburnt as greenish-yellow vapor, or kindles at the heat of the surrounding glowing coals, or at that of the lighted paper, and burns as a yellow flame.

Chemically speaking, when coal is heated out of the access of air, it is chiefly resolved into a large volume of gas, called "carburetted hydrogen," though containing more carbon than the gas obtained from the stagnant water of ponds and pools, as described at page 209; and from observance of this apparently trivial fact by the chemist, has originated the gigantic manufacture of "coal gas" for the illumination of our cities, towns, and dwellings.

The discovery of coal-gas was made by a chemist upwards of a century ago, but it was considered as a mere curiosity of the laboratory, and its practical application as an excellent means of artificial illumination, was not entered upon until within the last five-and-thirty years; the merit of this gigantic undertaking is divided amongst a host of the most eminent men, whose names adorn the scientific annals of our country, and who must be considered as the great benefactors of mankind, for the bright illumination of our cities and towns has contributed a most important share towards the prevention of many horrible deeds of darkness.

The merit of first conducting upon a comparatively large scale the examination of the different varieties of coal, the production of gas, its quantity, its purification, its illuminating power, and the construction of the argandburner for its combustion, is solely due to a philosopher of the present day, who, educated in the same school of Inductive philosophy as his great predecessor, has adorned the science of Chemistry with numerous discoveries and experiments, more particularly in those departments relating to the recondite functions of organized beings, and to the extraordinary nature of organized products; and whose extensive, varied, and sound information concerning the whole science, and clear explicit manner of teaching its facts by lectures, is certainly without parallel; and whose "Manual is the best collection and arrangement of chemical science existing."

The expressions used by a pupil regarding his master in the chemistry of the "olden time," are here copied, with sincerity and gratitude, by a pupil, as applicable to his first instructor in the chemistry of the present day; -"he is a man not of words, but of deeds; a philosopher who eminently seeks to render science popular and intelligible to all capacities."

Returning to the fuel, from whence the vivid jets of gas issued and led to the above passing notice of its discovery and applications, we discover that when the volatile hydrogen and part of the carbon are thus consumed, the yellow flame ceases, and the remaining carbon, containing no volatile matters, but generally contaminated with earthy matters, then enters into combustion, constituting the glowing of the cinders, and producing carbonic acid alone, which being invisible, the fire is said to "burn

clear;" this is more particularly the case during a "frosty night," because the external air being extremely cold, and that of the room extremely warm in comparison, the latter rushes towards the fire, or fans or blows it with greater force in its rapid endeavor to escape through the chimney to the cold air without, than it does when there is not so great a difference between the temperature and the specific gravity of the interior and the exterior atmosphere.

Upon the surface of the red-hot glowing cinders, a beautiful pale blue flame often appears; it results from the carbonic acid that is formed near the lower portions of the fuel in its ascent through the upper, combining with more carbon, and producing an inflammable compound, called "carbonic oxide;" the same flame also appears upon brick and tile kilns, which are heated by coal ashes; and in such situations it has been occasionally mistaken for the "ignis fatuus."

The blue flame is supported by the oxygen of the air combining with the excess of carbon, so that carbonic acid is again produced; and this is the reason that a piece of paper cannot be lighted with readiness on the top of a "cinder-fire," the heat may be sufficient to char the paper, but it cannot inflame, because it is enveloped by the carbonic acid, which is slowly rising; if this be quickly dissipated by the breath, or by suddenly opening the door, the paper thus freed is fanned into flame by the contact of the air.

If the piece of paper be held amidst the glowing cinders near the bottom bars of the grate, where the fresh air first arrives, it will generally kindle immediately, but will not do so if the cinders are only dull red hot,

because such degree of heat, though capable of producing volatile matter from the paper, is incapable of kindling such product; indeed it requires a white heat for its accension; this is obtained either by fanning the fire, or blowing it with the bellows, to excite more rapid chemical affinity between the elements of the fuel and the oxygen of the air.

We frequently hear of thatched buildings, barns, and hay-ricks being accidentally set on fire, from the wadding of a gun incautiously discharged near them, and lodging in the thatch; the wadding may not be hot enough to do this immediately, but by remaining in the thatch or hay for a time, it is fanned by the wind into flame, and then instantly establishes an extensive conflagration.

The bright and dark spots presented in a "clear glowing cinder fire," depend upon the intensity of the combustion of some parts of the fuel being greater than others; and these are liable to great variations, by the draught of air proceeding towards the fire; and whilst watching such variations, the imagination soon becomes active in discovering grotesque resemblances between the forms of the fuel and those of familiar objects.

When the fire that has afforded so much information is "burnt out," the ashes in the grate consist of carbon and a small portion of earthy matters; the carbon is capable of burning in a very strong heat, and the ashes are accordingly collected as fuel for tile and brick kilns.

The utility of coal as a source of artificial heat and light needs no comment; the wisdom and beneficence of The Almighty, displayed in the occurrence of extensive

strata of coal where forest fuel is scarce, calls forth our admiration and gratitude.

In this country, "a land whose stones are iron," these ores could not be obtained without the aid of coal, to produce steam as the motive power of the engine, and draw them forth from the mine; neither could they be reduced to the metallic state, without the agency of coal and limestone. We accordingly find that The Creator has associated the ore of iron or the "iron-stone" with the very agents required for its extraction and reduction.

But the incessant demands that are made upon these subterranean stores of treasure, compel the miner to descend to greater depths, and to encounter greater perils, than were originally needed; and most particularly on account of the air of the mine being rendered indammable and explosive, by a gaseous exhalation of carbon and hydrogen, similar in composition to the "carburetted hydrogen" or stagnant waters, as mentioned at page 209; this in coal mines is called “ The fire-damp," to distinguish it from the natural exhalation of carbonic acid gas, that frequently occurs in limestone and chalk quarries, which is not inflammable, but produces suffocation, and is called "The choakdamp.

"The fire-damp" was long unconquerable, and the most terrific explosions, attended with dreadful loss of human life and destruction of machinery, were of extremely frequent occurrence; but The Almighty, who ordained its presence in the mine, permitted the great philosopher-to whose memory a feeble tribute has been paid during this inquiry-permitted him, to reflect, examine, and experiment upon its habitudes and composi