When the chamber, B, and the generator, A, are again in so cool a state that the fuel no longer decomposes the steam easily, the valves are so maneuvered as to stop the entrance of the latter, and to send a current of air into the apparatus in the same direction that the steam had just been taking.  The temperature thereupon quickly rises in the generator, A, while, at the same time, the combustion of the air gas produced soon reheats the chambers, B’.  The cooled products of combustion go, as before, to the chimney.  The position of the valves is then changed again so as to send a current of steam into the apparatus in a direction contrary to that which the air took in the last place, and the water gas obtained again is sent to the gasometer.

As will be seen, the process is entirely continuous, each current of air following the same direction in the apparatus (from left to right, or right to left) that the current of steam did which preceded it, while each current of steam follows a direction opposite that of the current of air which preceded it.

The inventor estimates that the cost of the coal necessary for his process will not exceed a tenth of a cent per cubic foot of gas.

One important advantage of the apparatus is that it can be made of any dimensions.  Instead of giving the generator the limited size and form shown in the engraving, with doors at the bottom for the removal of the ashes by hand from time to time, it may be constructed after the general model of the shaft of blast furnaces, with a hearth at the base.  Upon adding to the fuel a small quantity of flux, all the mineral parts thereof can be melted into a liquid slag, which may be carried off just like that of blast furnaces.  There is no difficulty in constructing regenerators of refractory bricks of sufficient capacity, however large the generators be; and a single apparatus might, if need be, convert one thousand tons of anthracite per day into more than five million cubic feet of gas.

* * * * *

LIGHTING AND VENTILATING BY GAS.

[Footnote:  A paper read before the Gas Institute, Manchester, June, 1885.]

By WILLIAM SUGG, of London.

Ever since the introduction of electric lighting, the public have been assured, by those interested in the different kinds of lamps—­arc, glow or otherwise—­that henceforth, by means of such lamps, rooms are to be lighted without heat or baneful products such as they assert attend the use of gas, lamps, or candles.  But I think it must not be implied, from what any one has said in favor of the electric light as a means of lighting our dwellings, that gas is unsuitable for the purpose, or that the glow lamp is a perfect substitute for gas, or that there is a very large difference throughout the year on the points of health, convenience, or comfort, or that the balance in favor rests with electric light