IMPROVE- MENTS IN THE MANUFACTURE OF GAS FOR BURNING
Year: 1878

page_text: LETTERS PATENT to Theophilus Redwood, of Earlscroft, Lower Clapton, in the
County of Middlesex, Professor of Chymistry, for the Invention of "IMPROVE-
MENTS IN THE MANUFACTURE OF GAS FOR BURNING."
PROVISIONAL SPECIFICATION left by the said Theophilus Redwood at the
Office of the Commissioners of Patents on the 22nd June 1878.
THEOPHILUS REDWOOD, of Earlscroft, Lower Clapton, in the County of Middlesex,
Professor of Chymistry. ** IMPROVEMENTS IN THE MANUFACTURE OF GAS FOR
BURNING."
The improvements comprised in this Invention relate to certain modifications of a
process for the manufacture of gas for which I (with another) obtained a Patent,
No. 2105, dated the 30th of May 1877. In that process the removal of tar and dust
from the gas immediately after it issues from the hydraulic main, before it has
cooled, and while it still retains much of the vapours of hydrocarbon oils in it, the
dilatation or expansion of the gas by means of an exhauster, and the addition of
steam to it during its passage through the part of our apparatus called the converter,
are important features of the Invention, through the influence of which we are
enabled to apply to the gas the required degrees of heat for increasing its volume
and otherwise augmenting its value as a source of light.
The modifications I now introduce relate to the materials that may be used, and
the method of packing or arranging them in the part of the apparatus called the
converter.
I find that, through the combined influences above stated, I can employ other
inorganic compounds of the metals of the earths or alkaline earths besides those
mentioned in the Specification in the previous Patent; thus, glass or slag may be
employed, and also other substances, when these are so combined and prepared as
that masses of them shall have a porous texture, or I may replace non-metallic
substances by pieces of iron similarly arranged in the converter. I also find it

page_text: advantageous in the use of inorganic materials which are comparatively bad con-
ductors of heat to introduce pieces of iron among such materials, so as to promoto
an equalization of heat through the converter, and thus to prevent the gas from
passing through without being subjected to the requisite amount of heat.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Theophilus Redwood in the Great Seal Patent Office on the 20th
December 1878.
THEOPHILUS REDWOOD, of Earlscroft, Lower Clapton, in the County of Middlesex,
Professor of Chymistry. " IMPROVEMENTS IN THE MANUFACTURE OF GAS FOR
BURNING,"
The improvements comprised in this Invention relate to certain modifications of
a process for the manufacture of gas for which I (with another) obtained a Patent,
No. 2105, dated the 30th of May 1877. In that process the removal of dust and the
solid and more easily condensible constituents of tar from the crude gas as it issues
from the hydraulic main, the introduction of the thus partially purified gas into the
part of our apparatus called the converter, together with as much as possible of the-
volatile hydrocarbon oils usually present in the tar, the dilatation or expansion of
the gas by means of an exhauster, and the addition of steam to it during its passage
through the converter, are important features of the Invention, by the combined
influences of which we are enabled to apply to the gas and vapours the required.
degree of heat for increasing the volume of the gas by breaking up the more
complex and condensible molecules and converting them into permanent gas, and
for otherwise augmenting the value of the gas as a source of light.
In that process the gas is subjected, as it passes through the converter, for a.
limited time to a temperature of about 1100° Fahrenheit. For effecting this pur-
pose the converter is filled with balls or masses of solid substances arranged so as to
break up the current of gas and expose to it a large heated (surface. The solid
substances used in the converter are most efficacious when they have a porous or
spongy texture, and I have found that other substances besides those named in our
Patent, No. 2105 of 1877, if brought into this condition, may be used with effect.
Thus, glass, slag, brick, or baked clay, and other similar substances, may be used if
reduced to powder and afterwards made into a paste by mixing them with some
agglutinating and other materials which, when the paste has been dried and baked,
shall cause it to have a porous texturo, so that it may be easily permeated by
the gas.
The modifications I now introduce in that processs relate to the materials that
may be used in the converter, and the method of preparing such materials so as to
increase their efficacy, by causing them to be very porous, and otherwise adapted
for the purpose here contemplated.

page_text: I use china or other dry clay as an agglutinating material, and I use a mixture of
equal parts of powdered alum and bicarbonate of soda for the purpose of causing
the required porous texture of the prepared balls or masses. I also use iron nails
or other small pieces of iron for aiding the conduction of heat into the centres of
the porous balls, and through the balls to the centres of the converting cylinders.
This method of preparing the balls is applicable to those made with plaster of
Paris, which I prefer, and also to those made with the other materials I have named.
The following example will serve to illustrate my method of preparing the balls.
I take ten pounds of plaster of Paris and ten pounds of china clay, and to those I
add two pounds of powdered alum and two pounds of bicarbonate of soda. Having
thoroughly mixed these powders together, I add sufficient water to form a plastic
mass, which is divided into balls or masses about the size of an egg. By the mutual
reaction of the alum and carbonate of soda, carbonic acid gas is evolved in the paste,
which causes the balls to swell and become porous, like the rising of dough in
making bread. While the balls are still soft I introduce into each ball at different
parts of its surface five or six cast-iron nails long enough to pass from the circum-
ference to near the centre. The balls are afterwars dried and baked, when they
retain their porous condition.
These porous masses are employed in the treatment of the gas in the manner
described in respect to the use of plaster of Paris in its natural or usual form in the
Specification of the said former Patent, No. 2105, in the year 1877.
Having thus represented the nature of my said Invention, and the manner of
applying the same, I would have it understood that I do not confine myself to
the exact details as herein given, but I claim,-
The use in treating and improving illuminating gas of porous masses prepared
substantially as described.
I also claim the introduction of metallic bodies in the said porous masses to aid
the passage of heat through and amongst them.
In witness whereof, J, the said Theophilus Redwood, have hereunto set my
hand and scal, this Eighteenth day of December, in the year of our Lord
One thousand eight hundred and seventy-eight.
T. REDWOOD (LS)