We have already noticed the fact that very many country people are introducing gas of their own manufacture, and that, after the first outlay for the fixtures, the gas costs less than the price paid by citizens. So much is the custom on the increase, that several manufactories exist, in different places, for preparing the apparatus. We shall take that of the " Maryland Portable Gas Company" as our illustration, and merely state that the simplifying of the machinery has been attended with such success, that the difficulties and dangers of the manufacture have vanished, and a new era in the mode of lighting private dwellings, churches, hotels, public and private schools, villages, factories, etc, has been opened. Gas lights, heretofore considered a luxury only to be enjoyed by those residing in cities, can now be employed in every place. Simplicity, safety, and economy, have been studied, and the results are so satisfactory that we anticipate a large business fo? the manufacturers, and increased orders for gas fitters.

Our illustration represents a simple cylindrical vessel, containing the oil from which the gas is generated. The retort is an iron, hollow cylinder, with a spheroidal bottom and flat cover, bolted and screwed to a projecting rim. The stove containing the retort is of sheet or cast iron, arranged upon the most approved plans, to economize the heat. The siphon box, or condenser, is a cast-iron vessel, with a movable lid bolted and screwed upon it. This is divided into compartments, and half-filled with water, with a siphon attached, so as to keep the water at all times to its proper level. The water tank, in which the gasometer floats, is made of wood or iron, and placed upon the surface of the ground, or, which is better, sunk to the level of the water. The gasholder is of sheet iron, suspended upon fixed pulleys, and forms the receiver for the gas when generated and ready for consumption. The reservoir communicates with the retort by a feed-pipe, or by a feed-pipe and cock, through a siphon screwed into the cover of the retort.

This siphon connects with a tube suspended perpendicularly in the middle of the retort, pierced with small holes in its lower end. Through this feed-pipe and siphon the liquid passes into the tube thus suspended, and, by the small holes at the end of the tube, becomes dispersed upon the. bottom and sides of the retort.

The working of the machine, and management of it, require no more than ordinary skill, and may be safely intrusted to a domestic. A fire is made in the stove as in an ordinary fnrnace, and the retort is heated to a bright cherry-red heat The cock is then opened, to allow the oil to pass in through the pipes from the reservoir upon the heated sides and bottom of the retort, where it is instantaneously converted into gas.

Ascending from this decomposing chamber, the gas is forced through a superstratum of chemical substances suspended upon an iron grating for its purification into a vacant upper chamber, thence it is conducted by an iron pipe into the condensing box. This iron pipe, passing through the cover of the condensing box, descends below and discharged the gas into the water of the condensing box. Thence it rises into the vacant chamber above the water, which, becoming filled, forces the gas again into the water under one of the several compartments above referred to, into a second chamber, and then on through consecutive baths before it finds its exit from the last of the series of consecutive chambers.

This exit is through a pipe which communicates from the condenser with, the water tank into which it enters, and, passing through the water above, again descends, and discharges the gas into the water for its last bath, thence it rises into the vacant chamber of the gasometer, ready for use. Connected with the siphon of the condenser is a small covered vessel, which receives the impurities washed from the gas in its passage through the baths. The machine, as above described, occupies a space of eight feet by twelve, and in height thirteen feet, with the tank upon the ground. If the tank be sunk, then the height will be but seven feet.

The material used is an oil from rosin, though not what is generally understood as rosin oil. It is an earlier, cheaper, and better, product of collopbony, decomposable at a lower, and therefore more economical degree of heat. There cannot be found, in the whole range of chemistry, a compound more richly laden with illuminating qualities, or yielding gases more innocuous in respiration, or less injurious to furniture, for it contains neither carbonic acid nor sulphuretted hydrogen.

The supply of this material is inexhaustible, and any anticipated demand can scarcely enhance the price. It is now. delivered at the Company's Works, in Baltimore, at eighteen cento per gallon. Each gallon of the raw material may be safely estimated to make one hundred cubic feet of gas from this machine. The apparatus, as above described, with a gasometer of the capacity of a hundred and thirty cubic feet, will contain an average of a week's supply, to an ordinary family, the year round, and is sold at the Company's Works, in Baltimore, complete, for $350. They are made, however, of any required capacity, and adapted, in form and size, to the necessities of the space they are to occupy, and the requirements of the burners they are to supply.

Of course these requirements and necessities are so varied, and se materially increase or lessen the cost of the whole machine, that it is difficult to furnish a tariff of prices suited to all occasions; and persons intending to employ this apparatus, will of course address the manufacturers, who have spent much time and money to bring about the results now consummated. The principle and its application through this machine, are now no longer a matter of mere experiment. We congratulate the public on this new source of comfort being perfected, and brought within the reach of country families.