64: REPORT— 1868. 
the ignited mass, taking up an additional equivalent of carbon, and thus 
forming carbonic oxide. The heat thus produced distils off carburetted 
hydrogen and other gases and vapours from the fuel as it descends gradually 
towards the grate, and the carbonic oxide already named, diluted by the 
inert nitrogen of the air, and by any small quantity of unreduced carbonic 
acid, and mixed with these gases and vapours distilled from the raw fuel, is 
finally led off by the gas-flue to the furnace. The ashes and clinkers that 
accumulate in the grate are removed at intervals of one or two days. 
E is a pipe for the purpose of supplying a little water to the ash-pit, to be 
decomposed as it evaporates and comes in contact with the incandescent fuel, 
thus forming some hydrogen and carbonic oxide, which serve to enrich the 
gas; G isa small plughole by which the state of the fire may be inspected, 
and the fuel moved by a bar if necessary ; and p is a sliding damper by which 
the gas-producer may be shut off at any time from the flue. 
It is necessary to maintain a slight outward pressure through the whole 
length of the gas-flue leading to the furnaces, in order to prevent the burn- 
ing of the gas in the flue through the indraught of air at crevices in the 
brickwork. 
Where the furnaces stand much higher than the gas-producers, the re- 
quired pressure is at once obtained; but more frequently the furnaces and 
gas-producers are placed nearly on the same level, and some special arrange- 
ment is necessary to maintain the pressure in the flue. The most simple 
contrivance for this purpose is the “ elevated cooling-tube.” The hot gas 
is carried up by a brick stack, n, to a height of eight or ten feet above the top 
of the gas- producer, and is led through a horizontal sheet-iron cooling-tube, 
z (fig. 1), from which it passes down either directly to the furnace, or into 
an underground brick flue. 
The gas rising from the producer at a temperature of about 1000° Fahr., 
is cooled as it passes along the overhead tube, and the descending column is 
consequently denser and heavier than the ascending column of the same 
length, and continually overbalances it. The system forms, in fact, a siphon 
in which the two limbs are of equal length, but the one is filled with a heavier 
gaseous fluid than the other. 
In erecting a number of gas-producers and furnaces, I generally prefer to 
group the producers together, leading the gas from all into one main flue, 
from which the several furnaces draw their supplies. 
The Puddling-Furnace proper is shown in figures 2, 3, and 4. 
Fig. 2 is a front elevation of the furnace, showing the gas-reversing valve 
and flues in section. 
Fig. 3 is a longitudinal section at A, B, c, D (fig. 4). 
Fig. 4 is a sectional plan at 1, m (fig. 3). 
The peculiarity of the regenerative gas furnace, as applied either to 
puddling or to any other process in which a high heat is required, consists 
in the utilization in the furnace of nearly the whole of the heat of combus- 
tion of the fuel, by heating the entering gas and air by means of the waste 
heat of the products of combustion after they have left the furnace, and are 
of no further use for the operation being carried on, The waste heat is, so 
to speak, intercepted on its passage to the chimney by means of masses of 
firebrick stacked in an open or loose manner in certain chambers, called 
“ regenerator chambers,” ©, E, E,, C, (fig. 3). 
On first lighting the furnace the gas passes in through the gas-regulating 
valve, B (fig. 2), and the gas-reversing valve, B’, and is led into the flue, m, 
and thence into the bottom of the regenerator chamber, c (fig. 3); while the 
