IMPROVEMENTS IN THE MANUFACTURE OF GAS
Year: 1876

page_text: LETTERS PATENT to Charles Frederick Mathieson, of 7, Mincing Lane, in the
City of London, for the Invention of "IMPROVEMENTS IN THE MANUFACTURE
OF GAS."
Sealed the 11th May 1877, and dated the 25th November 1876.
PROVISIONAL SPECIFICATION left by the said Charles Frederick Mathieson
at the Office of the Commssioners of Patents on the 25th November 1876.
CHARLES FREDERICK MATHIESON, of 7, Mincing Lane, in the City of London.
"IMPROVEMENTS IN THE MANUFACTURE OF GAS."
This Invention has for its object improvements in the manufacture of gas.
In the manufacture of gas, in place of working the retorts single in the usual
manner, it has been attempted to couple them together in sets, say, three retorts in
each set, in such manner that the gas generated in the lowest retort passes into the
middle retort, and together with the gas generated in the middle retort passes into
the uppermost retort, from which one outlet pipe conveys away the whole of the
gas generated in the three retorts, which are thus combined together to form a set.
Up to the present time all attempts to work in this manner have entirely failed, in
consequence of the passages between the retorts and the outlet pipe constantly
getting stopped so as to impede the passage of the gas. This difficulty I have found
to arise in consequence of the apparatus not being properly constructed and propor-
tioned, and for want of proper precautions in charging the retorts. I connect the
lowest retort with the middle retort at the front outside the furnace by a cast-iron
connection of an internal diameter of eight inches. The middle retort I connect
with the upper retort within the furnace at the back by a fire-clay connection
having an internal diameter of fourteen or fifteen inches. The outlet is from the
front of the uppermost retort, and is formed in cast iron; it has an internal diameter
of ten inches. Within the middle retort I form a ridge so placed and of a height
sufficient to prevent the coal encroaching on the passage way between this rotort
and the retort below.
In charging the retorts I employ the scoop, and to ensure the coal being laid
evenly in the retorts I fix across the further end of the scoop an iron bar connecting
the two sides. When the scoop is turned over, and the coal deposited in the retort,
as the scoop is drawn back the bar passes over the top of the heap of coal and levels

page_text: it down into an even layer, covering the bottom of the retort. I always employ
fire-clay retorts and an exhauster to draw the gas from them, and I do not allow of
any dip in the hydraulic main except at the time of charging. I charge first
the uppermost retort of the set, then the middle retort, and lastly the bottom retort
one after the other in succession as rapidly as possible.
I have two sets of retorts in the same furnace, and I charge the sets alternately
at about two hour intervals. By working in this manner I obtain a large additional
yield of gas, and experience no inconvenience from stoppages.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Charles Frederick Mathieson in the Great Scal Patent Office on the
24th May 1877.
CHARLES FREDERICK MATHIESON, of 7, Mincing Lane, in the City of London.
"IMPROVEMENTS IN THE MANUFACTURE OF GAS."
This Invention has for its object improvements in the manufacture of illuminating
coal gas.
The manufacture of such gas is usually carried on in benches containing separate
retorts worked singly, but for producing a large increase of gas it has been
attempted to couple the retorts in sets of three placed one over another, so that the
gas generated in the lowest passes into the middle retort, and together with the gas
developed in the middle retort rises into the uppermost retort, from which one outlet
pipe conveys the total quantity of gas produced in the three connected retorts into
the hydraulic main. Up to the present time all attempts to work the combined
retorts have thoroughly failed, and been abandoned in consequence chiefly of constant
obstructions in the retorts and pipes stopping the passage of the gas.
This fatal
obstacle I have discovered to arise from defective construction of the apparatus and
disproportionate dimensions of its respective parts, as also from the want of pre-
cautionary contrivances and means to insure the proper charging of the retorts.
The remedies and improvements which I have invented prevent obstructions,
realize a large increase in the yield of good gas, and important savings in fuel, labour,
and plant. I place the fire-clay retorts horizontally one over another, and so closely
that they are in direct contact at the mouth, and I fill up the narrow space of about
1 inch between the respective bodies of retorts with a layer of fire-bricks 41/2 inches
wide. Then I connect the lowest retort with the middle retort at the mouth outside
the bench by a cast-iron circular tube about 6 inches long and of an internal diameter
of at least 8 inches. The middle retort I couple with the upper retort within the
bench at the back by a round hole in cach of about 15 inches diameter, and to
correspond or match exactly, and joined by thin fire-bricks properly cemented with
fire-clay to render the connection gas-tight. The outlet is from the mouth of the
uppermost retort, and formed of cast iron of an internal diameter of at least 10 inches.
Within and on the bottom of this uppermost retort at the edge of the round hole I
form a short and level fire-clay wall of a height sufficient to prevent the coal
encroaching on the rear passage from the middle retort.
In charging the retorts I employ a half cylinder scoop provided with a steel bar
of about 3/8 inch thickness, rivetted across the open end to connect both sides,
and rising from each side in a convex line about 2 inches, but quite level in the
central part. When the labourers have turned the scoop the charge of coal is
deposited in the retort in a long ridge of irregular elevation; they have then to
carefully withdraw the scoop over that ridge, and when about half the length is
outside the handle end should be depressed until the scoop is entirely withdrawn.
This bar spreads and levels the discharge of coal evenly over the bottom of the
retort, and the timely depression of the handle end of the scoop prevents the removal
to the mouth of the retort of any large pieces of coal there may be in the charge,

page_text: and which the labourers will often inadvertently fill into the scoop, although contrary
to strict orders.
The thickness of the charged layer of coal in retorts of about 8 feet 6 inches to 9 feet
length by 16 inches and 20 inches internal diameter, shape, should not exceed
5 inches in order to admit of perfect distillation of the charge, and with such a
charge the distillation is completed in about 2/3rds of the usual time now employed.
By the observance of this arrangement the product of good gas in each bench during
24 hours is immensely increased (more than 3 charges being added), and much fuel
saved, while one-third of the retort benches and apparatus are dispensed with,
besides the proportionate laborage and renewal of retorts and apparatus.
The production of pure gas and its free passage are also much facilitated. During
the distillation the use of an adequate exhauster is indispensable, and the dip pipe
should be adjusted at about half an inch dip into the hydraulic main, which ought
to be at least 3 feet from the top of the retort bench.
The operation of charging the retorts begins at the uppermost, continuing with
the middle, and terminating with the lowest in rapid succession, and one set in the
bench having been charged the second set of retorts is treated in the same manner
after an interval of about one hour and a half. The result of this interval is a better
mixture of all the gas, and an equal temperature of the retorts. If the retort bench
contains seven retorts the charging, of the seventh is performed immediately after
that of one set of three.
In order to secure the collective advantages from the enumerated improvements
it is necessary to observe the following rules invariably practised by well organized
gas works, videlicet -The careful maintenance of an equal temperature during dis-
tillation by a small supply of fuel every 15 minutes, the cleaning of the apparatus
once each month, and the avoidance of the use of coals which are very moist or in
too large pieces.
The accompanying Drawing shows a bench organized on my system.
Figure 1 represents the front elevation of a bench of six retorts formed of two
series of retorts three in each series.
Of
Figure 2 gives a side view of a series of three retorts exhibiting the two cast-iron
connections in front, and one circular fire-clay joint in the rear, with the adjacent
projecting cross wall, which confines the layer of coal in the uppermost retort.
the three retorts the lowest marked A communicates with the central retort marked
A' by the tubular joint a, and the central retort A¹ is connected with the uppermost
A by the circular rear joint marked a close to the projecting cross wall b. The upper-
most retort A bears on its front extremity the ascension pipe C, which leads to the
hydraulic main B. Each series of three retorts has only one ascension pipe marked C.
Figure 3 shows in two views the scoop with the rod steel bar across the end.
In conclusion I define my claim as follows, videlicet:-The construction of appa-
ratus for the manufacture of gas substantially, as described.
In witness whereof, I, the said Charles Frederick Mathieson, have hereunto
set my hand and seal, this Twenty-third day of May, in the year of our
Lord One thousand eight hundred and seventy-seven