IMPROVEMENTS PURIFICATION OF COAL GAS AND OF COAL OILS
Year: 1860

page_text: LETTERS PATENT to William Renwick Bowditch, of Saint Andrew's,
Wakefield, York, Clerk, for the Invention of "IMPROVEMENTS
PURIFICATION OF COAL GAS AND OF COAL OILS."
THE
Sealed the 27th March 1861, and dated the 24th November 1860.
PROVISIONAL SPECIFICATION left by the said William Renwick Bowditch
at the Office of the Commissioners of Patents, with his Petition, on the
24th November 1860.
1. WILLIAM RENWICK BOWDITCH, of Saint Andrew's, Wakefield, York,
Clerk, do hereby declare the nature of the said Invention for "IMPROVEMENTS
IN THE PURIFICATION OF COAL GAS & OF COAL OILS," to be as follows:-
I pass coal gas through or over the hydrates of potash, soda, baryta,
magnesia, and alumina, the oxides of manganese, iron, copper, tin, zinc, or
other metals either in the hydrated or anhydrous condition except hydrated
peroxide of iron, and hydrate of lime, or through a mixture of any of these
substances, the substance or substances employed being in each case heated
to a temperature between 120° F. and a temperature short of dull redness.
I also pass coal gas, together with steam, through or over charcoal, coke,
or mixtures of these with alkalies, & also through the above-named materials
or mixtures of them heated between 212° F. & a dull red heat.

page_text: I also pass coal gas with steam through pipes heated or not, or other
suitable vessels which will contain the gas and steam, such steam being
rendered ammoniacal, with free ammonia or not as desired.
I also pass coal oils obtained by the distillation of coal or of coal tar
through vessels filled with heated purifying materials. & with or without steam.
as is above specified for gas.
After the gas has been passed through the above-named heated materials!
cool it, and consequently pass it through the ordinary cold purifying materials
to remove impurities rendered removable by the hot process.
SPECIFICATION in pursuance of the conditions of the Letters Patent. filed
by the said William Renwick Bowditch in the Great Seal Patent Office
on the 23rd May 1861.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
RENWICK BOWDITCH, of Saint Andrew's, Wakefield, in the County of York,
Clerk, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-fourth day of November, in the year of our
Lord One thousand eight hundred and sixty, in the twenty-third year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
said William Renwick Bowditch, Her special licence that 1. the said William
Renwick Bowditch, my executors, administrators, and assigns, or such others as
I, the said William Renwick Bowditch, 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 of Great
Britain and Ireland, the Channel Islands, and Isle of Man. an Invention for
"IMPROVEMENTS IN THE PURIFICATION OF COAL GAS AND OF COAL OILS," upon the
condition (amongst others) that I, the said William Renwick Bowditch, my
executors or administrators, by an instrument in writing under my, or their, or
one of their hands and seals, 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 William Renwick Bowditch, do hereby
declare the nature of my said Invention, and in what manner the same is

page_text: to be performed, to be particularly described and ascertained in and by the
following statement, that is to say :-
To carry out the first part of my Invention, I proceed as follows:-I pass
coal gas (preferably that which has undergone the ordinary process of purifi-
cation) through or over the hydrates of potash, soda, baryta. magnesia, or
alumina, the oxides of manganese and of iron, either in the hydrated or
anhydrous condition (except hydrated peroxide of iron) (other oxides such as
those of copper, zinc, or tin will produce the same effect, but at their present
prices I have found them too expensive), or through a mixture of any of these
substances placed in any suitable vessel. The substance or substances em-
ployed being in each case heated to a temperature between 120° Fahrenheit
and a temperature short of dull redness, the best temperature being about
300 Fahrenheit. The aforesaid materials, except potash and soda, are best
fitted for use. in purification of coal gas, when they are in small lumps from
the size of a pea to the size of a walnut, as the gas then passes through them.
with facility. If in a state of powder, they may be formed into small lumps
by moistening with water, and stirring until they aggregate into lumps; they
are then to be dried, and to have the dust sifted out, when they are ready for
use in the hot purifiers. The best temperature for drying these substances is
from 200° Fahrenheit to 300° Fahrenheit. Potash and soda are best
employed when dissolved in a small quantity of water, and absorbed by bricks
broken into small pieces: when saturated with the alkaline solutions the bricks
are ready for use in the hot purifiers.
The vessels employed to hold the heated purifying materials may be of any
form, size, or material found convenient. I prefer to have them cylindrical
Each vessel should have an outer
and of cast iron. with a door at each end.
metallic casing or jacket made steam-tight. so that steam may be employed
as the source of heat to the purifying materials, such steam being applied by
injecting it between the purifying vessel and its outer coating, or water may be
converted into steam within the space between the purifier and its jacket by a
direct application of heat to the outer jacket. I prefer to pass in steam
heated to the proper temperature, and should not use direct heat if steam
were available. The purifiers may be fixed vertically, or at any convenient
angle with the horizon. which will allow the purifying material to occupy the
space within in such a manner as that no gas can pass through without
coming into contact with and passing through the heated purifying material.
They need not be more than three or four feet in length, and should be of
such breadth as will allow a ready passage to the maximum quantity of gas
made. Each purifier should contain about three feet of purifying material

page_text: disposed in one or more layers as preferred, through which the gas should be
made to pass.
The purifying material should be renewed from time to time according to
the quantity of gas manufactured, as a competent workman will soon ascer-
tain. Gas which has passed through the hot purifiers is to be cooled in the
ordinary manner, and to be passed through cold purifiers of the ordinary kind
containing slaked lime, or slaked lime and oxide of iron, after which it is fit
for use.
I prefer to subject the gas to the ordinary cold process of purification before
using the above processes, as then the hot purifying material will not become
clogged by tar and cooled by water which have passed the condenser, but
these will have been deposited in the cold purifiers. My process may, how-
ever, be applied to gas as soon as it leaves the condenser before it passes into
the ordinary purifier, but with less effect and more trouble than when the gas
has been first subjected to the cold process of purification.
My Invention may be applied to gas by consumers upon their own premises,
in which case the gas which leaves the meter is made to pass through a small
purifier containing the above-mentioned purifying materials heated to about
300° Fahrenheit, and subsequently through another purifier containing layers
of ordinary cold slaked lime after which it may be burnt. The pressure of
gas upon consumers' premises is not often sufficient to overcome much resist-
ance, wherefore the cold purifying materials should have the dust sifted out,
and then the gas will pass through the purifiers without any perceptible loss
of pressure.
Another part of my Invention is the passing coal gas. together with steam,
through or over charcoal, coke, or mixtures of these or either of them with
alkalis, or through the materials heretofore named, or mixtures of them heated
between 212° Fahrenheit and a dull red heat, preferring for the latter
materials a temperature of about 400° Fahrenheit. For this purpose the
charcoal or coke is broken into small pieces, from which the dust is sifted, and
(if alkalis be used) the charcoal or coke is saturated with concentrated solutions
thereof, when it is fit for use in the hot purifiers. Coal gas contains steam
or vapour of water, and when the gas containing this normal quantity of vapour
is passed through or over the above-named heated materials, some of the
sulphur, which was before irremovable, can be removed by cold slaked lime:
I prefer, however, to add to the gas more steam than it contains naturally.
and I find the best plan to be to send the gas over the surface of water
heated from about 140° Fahrenheit to 180° Fahrenheit, and subsequently
through the above-named heated materials. The quantity of steam thus

page_text: carried by the gas I find the best which can be employed. The surface of
heated water should be about twenty-five superficial feet for each fifty thousand
cubic feet of gas made per hour. When steam is generated at or above the
boiling point of water, and passed with gas into the hot purifier, a considerable
amount of illuminating matter is abstracted from the gas without any cor-
responding advantage in point of purity. The charcoal or coke when used
alone may be heated to about 500° Fahrenheit, but with alkalis it should not
be heated above 300° Fahrenheit. When the gas leaves the coke or charcoat,
it is to be cooled and purified as above directed.
Another part of my Invention is the passing coal gas with steam through
heated pipes or other suitable vessels which will contain the gas and steam.
In carrying out this part of my Invention, I prefer to use pipes or other
suitable vessels heated to about 500° Fahrenheit, and filled with any inert
material, such as broken bricks, to afford surface of contact, so that the gas
and steam may be brought into intimate contact. A pipe or vessel four feet
long filled with bricks, or other inert material will be sufficient; when
nothing is used to fill up the heated pipes or vessels, these should be from
eight to ten feet in length. The aqueous vapour existing in gas will of itself
suffice to convert a part of the irremovable sulphur compounds of gas into
removable compounds, but I prefer to add steam, and to effect this I pass the
gas over a surface of heated water, as is above specified; after this the gas is
to be passed through the cold purifiers, as above specified.
Another part of my invention consists in passing coal oils (that is, such oils
as are obtained by the distillation of coal schist or coal tar) through vessels
containing any of the above-named substances heated to about 380° Fahrenheit,
and prepared as directed for use in the purification of gas. The best and most
economical substance of all the above named i find to be binoxide of man-
ganese. The best mode of proceeding I find to be, to take the coal oil, after
it has been treated with acids and alkalis in the usual way, and to distil it
over the heated purifying material. When condensed, the coal oil is to be
washed with alkali and subsequently with water, upon which it becomes
nearly or quite colourless and of pleasant odour. When the washing, as
directed, after it has passed the heated purifying material, does not produce
an oil of good colour and odour, the hot manganese or other purifying material
should be changed.
I claim, as the first part of my Invention, the application to the purifying
of coal gas of the substances named in describing that part, heated and having
the gas transmitted through them, subsequently to which the gas is passed
through the ordinary cold purifying materials described, by which treatment of

page_text: gas injurious matters therein irremovable by the ordinary cold purification are
rendered removable, and are removed.
I claim, as the second part of my Invention, the passing coal gas with
steam either that ordinarily contained in it, or added to it, over the substances
named in describing that part of my Invention, and in manner described,
whereby a similar effect is produced.
I claim, as the third part of my Invention, the passing gas through pipes or
vessels as above described whereby a similar effect is produced.
I claim, fourthly, the purification of coal oils, as herein described.
In witness whereof, I, the said William Renwick Bowditch, have here-
unto set my hand and seal, this Twenty-second day of May, in the
year of our Lord One thousand eight hundred and sixty-one.
W. K. BOWDITCH. (L.S.)
R.