CERTAIN IMPROVEMENTS IN OBTAINING CARBONIC ACID FROM CERTAIN MINERAL SUBSTANCES
Year: 1840

page_text: SEWELL DE
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, THOMAS
ROBERT SEWELL, of Carrington, in the County of Nottingham, Lace Manu-
facturer, send greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria by Her
Royal Letters Patent under the Great Seal of Great Britain, bearing date at
Westminster, the Thirty-first day of December, in the fourth year of Her
reign, did, for Herself, Her heirs, and successors, give and grant unto me, the
said Thomas Robert Sewell, Her especial license, full power, sole privilege
and authority, that I, the said Thomas Robert Sewell, my executors, admi-
nistrators, and assigns, and such others as I, the said Thomas Robert Sewell,
my executors, administrators, or assigns, should at any time agree with, and
no others from time to time, and at all times during the term of years therein
mentioned, should and lawfully might make, use, exercise, and vend, within
England, Wales, and the Town of Berwick-upon-Tweed, my Invention of
"CERTAIN IMPROVEMENTS IN OBTAINING CARBONIC ACID FROM CERTAIN MINERAL
SUBSTANCES;" in which said Letters Patent is contained a proviso obliging me,
hand
the said Thomas Robert Sewell, by an instrument in writing under my
and seal, particularly to describe and ascertain the nature of my said Invention,
and in what manner the same is to be performed, and to cause the same to be
inrolled in Her Majesty's High Court of Chancery within six calendar months
next and immediately after the date of the said in part recited Letters Patent,
as in and by the same, reference being thereunto had, will more fully and
at large appear.

page_text: :-
NOW KNOW YE, that in compliance with the said proviso, I, the said
Thomas Robert Sewell, do hereby declare that the nature of my said Invention,
and the manner in which the same is to be performed, is particularly described
and ascertained in and by the following description thereof (that is to say):-
I would first premise that, within the last few years, carbonic acid has be-
come an article of great consumption especially with manufacturing chemists,
who use it extensively in the production of alkaline, earthy and metallic
carbonates, and, consequently to obtain this acid at a cheap rate and free from
combination with a large volume of any other gas has become a subject of
great importance to the arts. Heretofore carbonic acid has been obtained by
various methods, such as the combustion of charcoal in atmospheric air and by
the decomposition of native earthy carbonates through the agency of sulphuric
or of muriatic acid. The first of these methods yields carbonic acid mixed with
larger portions of atmospheric air and other gases, which impede or retard its
action upon the substances with which it is intended to be combined, and the
latter method is attended with great expence, arising from the cost of the
strong acid employed. This latter- method yields.the carbonic acid in a com-
paratively pure state, which is extremely..desirable for most purposes of
manufacture, and although the cost is very great, has been preferred in many
cases 'to the cheaper method of producing the acid by the combustion of char-
coal in atmospheric air.
.....
The object of these improvements. is to obtain carbonic acid in nearly
á pure state and at a small expence, and which is accomplished by heating.
certain mineral substances to a red heat in vessels from which the carbonic
acid evolved can be conducted to gas-holders; and there 'preserved for use.
The mineral substances which I use, and. the apparatus which I employ, will
be understood from the following description :-I take any of those minerals
which contain a large proportion of carbonate. of magnesia; and which are
known by the names of bitter spar, dolomite, and magnesian limestone; or
I take that description of iron-stone which contains a large proportion of
carbonate of iron, preferring, however, those minerals which contain carbonate
of magnesia. These minerals, or any of them (say, 'in pieces from one ounce
weight.upwards to not exceeding about two pounds); Iplace in a' retort;
such as is ordinarily employed in obtaining coal gas. for: 'the purpose of
illumination, and in such retort the minerals are heated to a red-heat, 'in
which state they give off carbonic acid gas in-great abundance. This gas"
is to be conducted into an hydraulic main and from thence into va purifying
vessel containing small gravel or coarse sand, or a mixture of them, or
any similar granular substances, which are to be moistened with water.

page_text: or a dilute solution of soda through the interstices, between which granular
substance the gas must be passed in order to arrest any particles of dust or of
decomposed organic matter, which I find such minerals usually contain; and
from this vessel the carbonic acid gas is to be conducted into an ordinary
gas-holder, wherein it is to be retained for use. I therefore claim as my
improvements in obtaining carbonic acid under the above in part recited
Letters Patent, the use of the above-mentioned minerals when heated in such
vessels as will admit of the carbonic acid being conducted and collected into
receivers, as above stated.
In witness whereof, I, the said Thomas Robert Sewell, have hereunto
set my hand and seal, this Twenty-fifth day of June in the year of our
Lord One thousand eight hundred and forty-one.
T. K. (L.S.) SEWELL.
AND BE IT REMEMBERED, that on the same Twenty-fifth day of June,
5 in the year above mentioned, the aforesaid Thomas Robert Sewell came before
our Lady the Queen in Her Chancery, and acknowledged the Specification
aforesaid, and all and every thing therein, contained in form above written.
And also the Specification aforesaid was stamped according to the tenor of
the Statute in that case made and provided.
Inrolled the Thirtieth day of June, in the year above written.