IMPROVEMENTS IN OBTAINING CARBONIC ACID GAS
Year: 1859

page_text: LETTERS PATENT to John Dauglish, of Tunbridge Wells, M.D., for the
Invention of "IMPROVEMENTS IN OBTAINING CARBONIC ACID GAS."
Sealed the 8th July 1859, and dated the 14th January 1859.
PROVISIONAL SPECIFICATION left by the said John Dauglish at the
Office of the Commissioners of Patents, with his Petition, on the 14th
January 1859.
J, JOHN DAUGLISH, of Tunbridge Wells, M.D., do hereby declare the nature
of the Invention for "IMPROVEMENTS IN OBTAINING CARBONIC ACID. GAS,"
to be as follows:-
This Invention has for its object improvements in obtaining carbonic acid
gas. For this purpose carbonate of lime or of other alkaline earth is distilled
in a closed retort; the carbonate is placed in the retort, which is then closed so
as to leave no communication between the atmosphere and the interior of the
retort. The retort is heated externally by a fire, and is connected by a pipe
with an air pump or apparatus for maintaining a vacuum within.the retort; by
this apparatus, before the distillation commences, the air is removed from the
retort, and a mixture of the gas with air is thus avoided, which is a point of
considerable importance in some of the manufactures in which the gas is
employed. As the distillation progresses the air pumps or apparatus remove
the gas from the retort as quickly as it is evolved, and may be caused to pass
In some cases I throw a
it into a gasometer in which it is stored for use.

page_text: jet of steam into the retort to facilitate the liberation of the gas; when this is
done, precautions should be taken to prevent the steam coming in contact with
heated iron, otherwise the steam will be liable to be decomposed, and the
carbonic acid gas rendered impure.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said John Dauglish in the Great Seal Patent Office on the
14th July 1859.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
DAUGLISII, of Tunbridge Wells, M.D., send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Fourteenth day of January, in the year of our Lord
One thousand eight hundred and fifty-nine, in the twenty-second year of
Her reign, did, for Herself, Her heirs and successors, give and grant unto
me, the said John Dauglish, Her special licence that I, the said John
Dauglish, my executors, administrators, and assigns, or such others as I, the
said John Dauglish, my executors, administrators, and assigns, should at any
time agree with, and no others, from time to time and at all times there-
after 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
OBTAINING CARBONIC ACID GAS," upon the condition (amongst others) that I, the
said John Dauglish, 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 John Dauglish, do hereby declare
the nature of the said Invention, and in what manner the same is to be
performed, to be particularly described and ascertained in and by the follow-
ing statement thereof, that is to say:-
This Invention has for its object improvements in obtaining carbonic acid
gas. For this purpose carbonate of lime or of other alkaline earth is distilled in
a closed retort; the carbonate is placed in the retort; which is then closed so.
as to leave no communication between the atmosphere and the interior of the.
The retort is heated externally by a fire, and is connected by a pipe
retort.

page_text: with an air pump or apparatus for maintaining a vacuum within the retort;
by this apparatus, before the distillation commences, the air is removed from.
the retort, and a mixture of the gas with air is thus avoided, which is a point
of considerable importance in some of the manufactures in which the gas-is
employed. As the distillation progresses the air pumps or apparatus remove
the gas from the retort as quickly as it is evolved, and may be caused to pass
it into a gasometer in which it is stored for use.
r
'
The following is the manner in which I prefer to proceed :-I employ an
ordinary iron gas retort about one foot diameter and 5 feet long, set in a
furnace in the usual way, in order to render the retort more perfectly airtight
than ordinary gas retorts. I make the joint between the retort and the cover
by means of a ring or washer of vulcanized india-rubber, and that this may
not be destroyed by the heat I construct the retort with a water neck, as is
shown by the longitudinal section Figure 1. It will be seen that the neck of
the retort is cast double and the space between the two parts is connected
with a water cistern by two pipes, one communicating with the top and the
other with the bottom of the water space. The cover also is made double and
between it and the retort a vulcanized india-rubber ring a is placed; b, b, are
two small tubes fixed in the cover, one at the top and the other at the bottom;
they communicate with the water space in it, and when the cover is in its'
place they enter holes which pass into the water space of the neck of the
retort; thus a circulation of water is maintained both in the neck of the retort
and the cover. Through the neck at c there is a passage, and with this a pipe
is connected leading to an air pump, having a cylinder about 6 inches diameter
and a stroke of 10 inches, and driven at 200 strokes per minute. From the
air pump a pipe passes to and dips down into a vessel containing water like the
bydraulic main of gasworks; this vessel is placed in a cistern in which water
circulates, and it is thus kept cool. In working the apparatus the retort is
filled with the carbonate of an alkaline earth, that which I prefer being lime-
stone, chalk, or whiting; the cover is then placed on the retort and the charge
brought up to a low red heat; when this heat is approached, the air pump is
set to work, and the air which is drawn out of the retort is allowed to escape
until carbonic acid gas is found to be coming over in a pure state; it is then
directed into the cooling vessel, and from thence it passes to a gasometer in
which it is stored. It is applicable for use in the manufacture of bread in the
manner described in the Specification of a former Patent granted to me, and
also in other manufactures in which carbonic acid gas is employed. The
process of distilling over the gas is usually complete at the end of about six or
eight hours. In some cases 1 throw a jet of steam into the retort to facilitato.

page_text: the liberation of the gas; when this is done, precaution should be taken to
prevent the steam coming. in contact with heated iron, otherwise the steam
will be liable to be decomposed, and the carbónic acid gas rendered impure.
When employing steam for this purpose I ordinarily do not employ vacuum.
. I arrange a steam pipe of small diameter to pass in at the back of the retort
exterior of the retort; it is furnished with a stop-cock to regulate the quantity
of steam admitted. The retort which I employ when using steam is an
earthenware retort such as is commonly used in the manufacture of gas; the
process is conducted in the manner already described. The gas and steam
are led away from the retort to the cooling vessel, where the steam is con-
densed and the gas cooled; the gas is then passed on as before into a gasometer.
In some cases I employ, however, a steam jet in conjunction with vacuum, in
which manner I am able to bring over the gas at a lower temperature than
when either steam or vacuum is used alone. For this purpose I bolt on to
an earthenware retort a water neck, as is shown by the longitudinal section
Figure 2, and the transverse sections Figures 3 and 4, and the interior surface
of the water neck and the cover I line with copper to prevent decomposition'
of the steam. The earthenware retort I fit within an iron retort, and fill the
space between the two with fine sand; in this manner I am able to prevent the
leakage of air which would otherwise take place through the pores of the
earthenware retort.
Having thus described the nature of my Invention and the manner of
performing the same, I would have it understood that I do not confine myself
to the exact details described; but what I claim is, the obtaining of carbonic
acid gas from carbonate of lime and other carbonates of the alkaline earths
by distillation in closed vessels or retorts, and collecting the carbonic acid gas
so obtained for use as herein described; also the employment of steam. within
the retort to facilitate the separation of the carbonic acid gas; also the
maintaining of a vacuum within the retort during distillation in order to
facilitate the separation of the carbonic acid gas.
In witness whereof, I, the said John Dauglish, have hereunto set my
hand and seal, this Twelfth day of July, in the year of our Lord One
thousand eight hundred and fifty-nine.
JOHN DAUGLISH. (L.S.)