Indeed it would be endless to enumerate the various sources of this gazeous fluid. A most curious variety of carburetted hidrogen gas has been discovered by the associated Dutch chemists (VAN DIEMAN, TROOSTWYCK, and others) which is procured from ether or alcohol, and has the remarkable property of generating a heavy oil when in contact with chlorine gas. Hence it has been termed oily carburetted hidrogen, or olifiant gas--it consists of carburetted hydrogen, supersaturated with carbon. The oil generated is heavier than water, whitish, and semi-transparent. By keeping, it becomes yellow and limpid; its smell is highly fragrant and penetrating--its taste somewhat sweet--it is partly soluble in water, imparting to it, its peculiar smell. A portion of this gas always accompanies the common carburetted hidrogen obtained from coal, and those sorts of coal that afford the largest quantity of it are best suited for the production of gas-light. The nature of carburetted hidrogen obtained from coal varies considerably according to the conditions under which it is obtained. The first part is always much heavier than the last, though still lighter than common air, and holds in solution a portion of oil, for on standing for some time over water it becomes lighter, and is found to require less oxygen for saturation than before. The oil which it held suspended, then becomes precipitated. The average specific gravity of the first and last gas mixed, which may be taken as an average of the whole specific gravity is to that of common air as 2 to 3--112lb. of common cannel coal produce at its _minimum_, from 350 to 360 cubic feet of carburetted hidrogen gas; but the same quantity of the best Newcastle coal, that is to say, such as coke, which, when laid on the fire readily undergoes a kind of semi-fusion, and sends out brilliant streams of flame, produces upon an average from 300 to 360 cubic feet of this gazeous fluid, besides a large portion of sulphuretted hidrogen, carbonic oxid and carbonic acid. Half a cubic foot of this carburetted hidrogen, fresh prepared, that is to say, holding in solution or suspension, a portion of the essential oil, which is generated during the evolution of the gas, is equal in illuminating power to from 170 to 180 grains of tallow, (being the quantity consumed by a candle six to the pound in one hour.) Now, one pound avoirdupoise is equal to 7000 grains, and consequently one pound of candles of six in the pound, burning one at a time in succession, would last (if we take 175 grains of tallow to be consumed in an hour) 7000/175 = 40 hours. To produce the same light we must burn one half of a cubic foot of coal-gas per hour; therefore, one-half multiplied by forty hours is equal to twenty cubic feet of gas in 40 hours, consequently equal to one pound of candles, six to the pound, provided they were burnt one after another. One hundred and twelve pounds of cannel-coal, produce, at its _minimum_, three hundred and