The two flues, E and E’, lead from the bottom of the two nearest regenerator on each side to the bottom of the generator A, and serve to bring the current of air or steam into contact with the fuel.  Valves, F and F’, placed in these flues, permit of regulating the current in the two directions.  Pipes, M and M’, provided with valves, G and G’, put the upper part of the generator in communication with the contiguous chambers, T and T’.  Other pipes, N and N’, with valves, H and H’, permit of the introduction of a current of air from the outside into the chambers, T and T’.  The pipes, O and O’, and the valves, I and I’, connected with a blower, serve for the same purpose.  The pipes, P and P’, and their valves, J and J’, lead a current of steam.  The conduits, Q and Q’, and their valves, K and K’, direct the gases toward the purifiers and the gasometer.  Finally, the pipes, R and R’, provided with valves, L and L’, are connected with a chimney.

The generator, A, is provided at its upper part with a feed hopper.  The doors, S and S’, of the ash box close the apertures through which the ashes are removed.

When it is desired to use the apparatus, the pipes, P, Q, and R, are closed by means of their valves, J, K, and L, and the valve, I, of the pipe, O, is opened.  The pipes, M and N, are likewise closed, while the flue, E, is opened.  On the other side of the generator the reverse order is followed, that is to say, the flue, E’, is closed, the pipes, M’ and N’, are opened, the pipes, O’, P’, and Q’, are closed, and R’ is opened.

A current of air is introduced through the pipe, O, and this traverses the regenerators, B, enters the chamber, T, and the generator, A, through the flue, E. As this air rises through the mass of incandescent fuel, its oxygen combines with an atom of carbon and forms carbonic oxide.  This gas that is disengaged from the upper part of the fuel consists chiefly of nitrogen and carbonic oxide, mixed with volatile hydrocarburets derived from the fuel used.  This gas, through the action of the air upon the fuel, is called “air gas,” in order to distinguish it from the “water gas” formed in the second period of the process.

The air gas, on issuing from the generator through the pipe, M’, in order to pass into the chamber, F’, meets in the latter a second current of air coming in through the pipe, N’, and which burns it and produces, in doing so, considerable heat.  The strongly heated gases resulting from the combustion traverse the regenerators, B’, and give up to the bricks therein the greater part of their heat, and finally make their exit, relatively cool, through the pipe, R’, which leads them to the chimney.  When the operation has been continued for a sufficient length of time to give the refractory bricks in the chamber, B’, next the regenerator a high temperature, the valve, I, is closed, thus shutting off the entrance of air through the pipe, Q. The valve, F, of the flue, E, is also closed, and that of the pipe, M, is opened.  The valves, G’, H’, L’, of the pipes, M’, N’, R’, are closed, and that, F’, of the flue, E’, is opened.  The valve, J’, of the pipe, P’, is then opened, and a jet of steam is introduced through the latter.