AN IMPROVEMENT IN THE AND HEATING Pure MANUFACTURE or Cas von LIONSALG HEATING PHD BOSS PURPO
Year: 1854

page_text: LETTERS PATENT to Thomas Isaac Dimsdale, of Hadley, in the County of
Middlesex, Gentleman, for the Invention of "AN IMPROVEMENT IN THE
AND HEATING Pure
MANUFACTURE or Cas von LIONSALG
HEATING PHD BOSS
PROVISIONAL SPECIFICATION left by the said Thomas Isaac Dimsdale
at the Office of the Commissioners of Patents, with his Petition, on the
23rd June 1854.
I, THOMAS ISAAC DIMSDALE, of Hadley, in the County of Middlesex,
Gentleman, do hereby declare the nature of the said Invention for "AN
IMPROVEMENT IN THE MANUFACTURE OF GAS FOR LIGHTING AND HEATING PURPOSES
to be as follows:-
My improvement in the manufacture of gas has for its object to increase the
volume or quantity obtainable from carboniferous and bituminous or carbonized
substances, either used alone or in combination with oleaginous or resinous
matter, and the simultaneous decomposition of water by their agency, so as to
render the employment thereof practicable with profit for illuminating or
heating purposes. The Invention is particularly applicable to the manufacture
of gas from bituminous schist or schale, lignite, peat, or other similar sub-
stances, with or without the admixture of oil, tar, or fatty matter of any
description.

page_text: The application of steam to increase combustion is now frequent and well
known, and the decomposition of the steam of water into its elements, by
bringing it into contact with incandescent charcoal or carbonaceous matter,
and also with iron, to produce gas for lighting, has been patented and used in
various forms. The novelty of my Invention consists in superheating the
steam of water before it is admitted into the retort containing the substances
submitted to destructive distillation for the production of gas. The steam
may be generated in any ordinary steam boiler worked at a low pressure, and
conveyed by pipes, which pass through the furnaces for heating the retorts,
and are so disposed therein that the steam in its passage through the pipes
shall become superheated to the degree required, when it may be admitted
into the retort. By this process a larger volume and better quality of car-
buretted hydrogen gas for lighting is obtainable than by any mode of applying
the steam from water that has been hitherto used or patented; and the coke
or charcoal from boghead coal, bituminous schist or schale, and other descrip-
tions of coke or charcoal may be made the means of producing hydrogen gas
of great heating power, even after these substances have been exhausted
of all the gas they will yield of any value for illuminating purposes.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Thomas Isaac Dimsdale in the Great Seal Patent Office
on the 23rd December 1854.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, THOMAS
ISAAC DIMSDALE, of Hadley, in the County of Middlesex, Gentleman, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-third day of June, in the year of our Lord
One thousand eight hundred and fifty-four, in the eighteenth year of Her
reigu, did, for Herself, Her heirs and successors, give and grant unto me, the
said Thomas Isaac Dimsdale, Her special license that I, the said Thomas
Isaac Dimsdale, my executors, administrators, and assigns, or such others
as I, the said Thomas Isaac Dimsdale, my executors, administrators, and
assigns, should at any time agree with, and no others, from time to time
and at all times thereafter during the term therein expressed, should and
lawfully might make, use, exercise, and vend, within the United Kingdom

page_text: of Great Britain and Ireland, the Channel Islands, and Isle of Man, an
Invention for "AN IMPROVEMENT IN THE MANUFACTURE OF GAS FOR LIGHTING AND
HEATING PURPOSES" upon the condition (amongst others) that J, the said
Thomas Isaac Dimsdale, by an instrument in writing under my hand and
seal, should particularly describe and ascertain the nature of the said
Invention, and in what manner the same was to be performed, and cause
the same to be filed in the Great Seal Patent Office within six calendar
months next and immediately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said Thomas Isaac Dimsdale, do hereby
declaro the nature of my said Invention, and in what manner the same is to
be performed, to be particularly described and ascertained in and by the
following statement (that is to say):-
My improvement in the manufacture of gas for lighting and heating
purposes, has for its object to increase the volume of the gas obtainable from
carboniferous or bituminous substances, by means of a novel mode of applying
known chemical principles to the production of gas for both heating and
lighting purposes. The production of gas for both these purposes is effected
by one continuous operation, and in a simpler, cheaper, and therefore more
practical way (consistent with the easy adaptation of the Invention to the
existing apparatus in gas works) than has hitherto been done. The decom-
position of water when heated to various degrees, by passing it over incan-
descent charcoal to obtain hydrogen gas and otherwise, as auxiliary to these
purposes, has not been hitherto effected in a manner to bring the process into
anything like general use. One difficulty has been the high value of charcoal,
which by the great majority of experienced gas manufacturers has been found
to render the cost of obtaining the gas greater than when coals are employed
in the usual method. I propose to obviate these objections by the means
herein-after detailed, premising that though my Invention is applicable with
some advantages in the use of all carbonaceous substances that are usually
employed to produce gas by destructive distillation, it is most particularly
eligible when used with bituminous shales, schists, or coals, peat, lignite, and
such matters as yield a residuum after such distillation, which may be cha-
racterized as charcoal, in contradistinction to the well-known coke, which is
the residual product in making gas from the ordinary descriptions of coal.
The increasing demand for coals as fuel renders it of public importance to
lessen their consumption for making gas by bringing other substances into
use for that purpose that are of inferior or no value as fuel, (such as the
bituminous shale or schists, peat, and lignites,) that either yield so small a

page_text: quantity, or so inferior a quality of gas, as to render them nearly useless
when operated upon by the ordinary processes. These substances I propose
to make profitably available. Hydrogen gas, obtained by the decomposition
of water, though possessed of considerable heating power, yields so feeble a
When water is
light as to render it inapplicable for lighting purposes.
decomposed by means of incandescent charcoal, the result is a combination of
two gases
in equal volume, namely, the oxide of carbon and hydrogen. The
oxide of carbon, which burns with a bluish flame, possesses also insufficient
power for lighting purposes. These gases, however, may be mixed with richer
carburetted gases produced by the distillation of resinous and fatty matters, or
boghead and cannel coal, and other bituminous shale or schist, as has been
abundantly proved by the experiments of scientific men, and processes founded on
this principle have in some instances been brought into use. In carrying out
my Invention I propose to generate steam in an ordinary low pressure steam
boiler, with the usual valve, to admit of its escape when it is not used as fast as
generated, or when the pressure accumulates beyond a certain point, say, six
pounds to the square inch. The steam is to be conveyed by a horizontal iron
pipe immediately over or under the groups of retorts, as they are now arranged
in gas manufactories, and this pipe may be well covered with felt, or any
substance which is a non-conductor of heat, in order to prevent the steam from
experiencing any material loss of temperature during its passage along thepipe.
From this horizontal pipe smaller perpendicular short branch pipes, provided
with stop cocks, are made to ascend or descend towards the centre of the
retorts. These branch pipes are to be connected by a screw joint, with pipe
passing through the lid or top of the retort, along the top inside, then down at
the back, where the pipe is divided into three pipes that pass along the bottom.
These bottom pipes are perforated with very fine holes underneath, so as to
permit the escape of steam, and their ends are closed. When the retorts are
not at work the small perpendicular pipes can be disconnected with the pipes
in the retort and taken off, and the stop cocks close to the horizontal pipe
being turned off, all escape of steam will be prevented. The retorts are to be
charged in the usual way, with bituminous shale or schist, boghead, cannel, or
ordinary coal, and heated precisely in the manner now done. When the retort
has become thoroughly hot, and the mass of the substance within heated
through, or nearly through, to a red heat, the stop cocks communicating with
the horizontal steam pipes are to be turned on, and the steam admitted; the
result of this will be, that the steam will become superheated in its passage
through the pipe placed inside at the crown or top of the retort, and after

page_text: descending through the pipe at the back of the retort, the superheated steam
will ascend through the incandescent mass in the retorts from the small aper-
tures pierced in the lower pipes. The steam will be thereby decomposed, and
hydrogen and oxide of carbon gases be evolved, which will combine with and
increase the volume of gas being produced by the destructive distillation of tho
substance with which the retorts have been charged. From bituminous coal,
schist, or shale a thick heavy gas is produced, rich in illuminating power, and
the addition of the hydrogen and oxide of carbon gases will not materially
diminish the illuminating power, and by no means in proportion to the increase
of volume they afford. Up to a certain duration of the process (being nearly
that at which the operation would cease for making gas under the old and
usual mode) the increase obtained in volume will vary in amount, according to
the quality of the substance with which the retort is charged, from twenty to
thirty per cent., before any apparent diminution of lighting power will occur,
or so as to render the gas unsuitable for illuminating purposes. When the
decrease in lighting power has reached to this point, the communication
between the retorts and the gas holders, which received gas intended for
lighting, is to be shut off, and the gas subsequently produced should be
conveyed into a separate gas holder, which gas will now be applicable to
heating purposes.
This gas will be of greater heating power than car-
buretted hydrogen, and the quantity produced by the continued passage of
the superheated steam through the incandescent mass in the retorts will
amount to more than the volume of the lighting gas transmitted to the first
gas holder. Thus, assuming that the quantity of gas which would have been
yielded under the old and ordinary process of gas making to be nine thousand
cubic feet per ton of ordinary coal, the quantity suitable for lighting purposes
will be increased up to nearly eleven or twelve thousand cubic feet, and the
produce from bituminous schist or shale augmented from five thousand
or six thousand to seven thousand or cight thousand feet, and the quantity
of gas for heating purposes yielded besides will be at least an equal quantity
If the material to be carbonized be peat, lignite, or other car-
bonaceous substance, yielding gas of feeble illuminating power, it may be
saturated previous to being put in the retort, or partly saturated, with any
dissolved resinous, oleaginous, or fatty matter, or a proportion of boghead coal
mixed therewith, with or without such saturation, and then heated in the
manner above described. The ash or charcoal of boghead coal or shale, which
has been previously used and exhausted of all the gas it will yield suitable for
lighting, may be again used for producing gas for heating. The charcoal
more.

page_text: obtained from lignite, peat, or wood, when in an incandescent state, being
capable of decomposing the steam of water, may all be used in the above-
described manner for that purpose; and if the gas be required for illuminating
purposes it may be carburetted by putting into the retort along with them dried
peat in small lumps, or pulverized sawdust, or ground charcoal saturated with
any oleaginous, fatty, resinous, or tarry matter, or with naphtha. I would here
observe, that the fatty, oleaginous, resinous, or tarry matters should be mixed
with the dried peat, sawdust, charcoal, or other solid carbonaceous substances
before the latter are placed in the retort, and not added thereto while in the
retort. Charcoal being useful for many purposes to which coke is not appli-
cable, it is desirable not to mix substances in the retort which yield these
different products; otherwise, by so doing, the mixture will be of little or no
value, as the charcoal will almost destroy the value of the coke as fuel, and the
coke will destroy the value of the charcoal for other purposes, and the profit
that may be realized by the sale of either will be thus lost.
By this method of superheating and using the steam of water no disarrange-
ment or alteration of the existing apparatus now in use at gas works is required
beyond the perforation necessary in the lids or other part of the retorts to admit
the pipes conveying the steam. The steam boiler and main horizontal pipe,
with its smaller perpendicular branch pipes, being external, and entirely inde-
pendent of the existing apparatus, the latter need not be disturbed on their
account. The pipes to be connected with the perpendicular pipes, as before
mentioned, and that enter into the retorts, are so placed in the retorts as to be
capable of removal or renovation without inconvenience when burned or
otherwise injured.
Having now described my Invention of "An Improvement in the Manu-
facture of Gas for Lighting and Heating Purposes," and also the means of
carrying the same into effect, I wish it to be particularly understood that I do
not claim the decomposition of water, and causing the gases produced thereby to
commingle or become mechanically mixed with other gases obtained from the
destructive distillation of carbonaceous or bituminous liquid or solid matters;
nor do I claim adding fatty, oleaginous, or resinous substances to solid carbo-
naceous matters in retorts, for the purpose of obtaining therefrom carburetted
hydrogen gas; but I do claim the method herein described of operating upon
carbonaceous or bituminous substances, (capable of yielding combustible gas
for lighting and heating.) by the introduction into the retort during the
process of distillation of jets of superheated steam, for the purpose of decom-
posing the same, and causing its elements to combine in a nascent state

page_text: with the gases evolved from the carbonaceous or bituminous substances con-
tained in such retort.
I also claim mixing with solid carbonaceous matters, as above set forth,
fatty, oleaginous, or resinous substances, previous to the same being placed in
the retorts for the production of gas.
In witness whereof, I, the said Thomas Isaac Dimsdale, have hereunto
set my hand and seal, the Twenty-third day of December, in the year
of our Lord One thousand eight hundred and fifty-four.
Witness,
J. W. MOFFATT,
66, Chancery Lane.
THOS J. DIMSDALE. (L.S.)