It is conceded by all eminent gas engineers that it must not be supposed that gas is produced directly from coal or other materials ; for observation leads to the conclusion that tar (a mixture of oils) is the first product, which is subsequently decomposod and partially converted into gas. If the temperature does not rise above a red heat, tar is produced in great quantities with little or no gas. It will be understood, then, that in the retorts where coal, wood, _ rosin or oil are introduced, a large proportion of the vapors of tar are not decomposed, because they do not come in actual contact with tho red-hot sides of the retort, and therefore condense more or less into tar. Engineers have tried to remedy the difficulty by lengthening the retorts, and by re-passing tho vapor over large heated surfaces. But another and a more serious difficulty arose; for it was discovered that gas which is generated at a cherry red heat is also decomposed if allowed to remain in contact with bodies at that temperature. The gas, thus kept heated, is separated from the carbon which it had taken lip when in the nascent state, and is deposited, in the form of a hard coating, against the interior of the retort, or of lampblack on the coke. Thus, instead of tar, useless lampblack and an injurious crust were produced, and the gas itself was of poorer quality; for it is the carbon combined with the hydrogen that gives the flame of gat, oil, tallow and burning fluid their illuminating power. The problem to be solved, therefore, was to contrive aa arrangement by which every particle of vapor evolved from the materials should be forced into close contact with the red-hot surface of tho retort, but not allowed to romain there after the gas was generated. In the retort shown, (Fig. 1,) Mr. Aubin claims to have combined the necessary features to produce the desired effect, and to have obtained, besides, other practical and economical advantages, which will be made apparent in the description. a is the retort. It is nearly a hemisphere, surrounded with the groove, b, which is filled with fusible metal, and in which dips the rim . of the cover, c, which thns affords a very con- l venient and effectual way of opening and (closing the retort perfectly tight, d is a flange around the groove, to support the retort upon the brick-work of the furnace, thus making it perfectly independent of it. One to four or more retorts are placed in a row, and are heated by one fire. They generate one hundred feet of very superior gas per hour each, and last, when in constant operation, from six to twenty-four months, according to their distance from the firo. When they are worn out or cracked they can be taken out and replaced in five minutes by the operatives them-selveB without stopping the working of the bench, and at a cost of from $6 to $10. A bench of three to eight retorts can supply villages and towns of 1,500 to 10,000 inhabitants, and can be worked economically and profitably where not more than one large building is to be supplied, as the heat of the retorts is brought up in about two hours. is the oscillating charger. It is a thin vessel of wrought or cast iron, the lower part of which is the counterpart of the retort, and fits it. It has an opening aty, which is partly closed by a perforated plate or otherwise. In the charger are placed the gas-making materials, which oan be, according to localities, eoal, rosin, grease, asphaltum, tar, cotton seed, cotton waste from machine shops mixed with sawdust, charcoal, or other light substance to graduate the action of the heat. As soon as the heat reaches the materials in the charger, vapors are generated, which, by their expansive force, oscape through the aperture, f, and slightly raise the charger, which, from its weight, falls back in its place, driving away the newly made gas, which is conducted through the neck, g, to the oondensersj puri- for the last six months, a rery beautiful light is procured from Albert coal, rosin and sawdust. The engravings which we give show the general arrangement adopted at Palmyra, though very notable improvements have heen introduced in the system by the inventor since these works were erccjted. It is claimed that from coal a much larger quantity of gas of a more uniform quality is produced than in the horizontal retorts, and in a much shorter time. From rosin, 12 to 18 feet of gas are generated per pound; from tar, grease, bones. c, an equivalent quantity is also obtained. Indeed, when the rosin has been used, the staves of each barrel containing it afford 400 feet of good gas, and two bushels of charcoal. The arrangement does away with all danger of explosion in the retorts, and of fire from the over-running of the rosin as used in the old process. Fig. 2 shows the plan of the gas-works complete in one building. When the freezing of water is not frequent in winter, the gasholder can be placed outside. Small villages would find three to six retorts sufficient, instead of eight, as shown in the plan; and for larger cities, a repetition of the tench would be tha only modification. Fig. 3 is an interior elevation of the same. Fig. i is a perspective view of the building, showing that it can be made ornamental in a village, without an increase of cost. The Aubin G as-W'orks Co. have acquired the different patents for the United States, and sold the right for California, New Jersey, and some smaller territories. For further information apply at the ofEce of the company, No. ii State St., Albany, N. Y. The patents taken out by Mr. Aubin, the inventor, bear date of January 8, 1856, April 81, and June 23, 1857,