A METHOD OF EXTRACTING OR MAKING TAR, PITCH, ESSENTIAL OILS, VOLATILE ALKALI, MINERAL ACIDS, SALTS, AND CINDERS, FROM PIT COAL
Year: 1781

page_text: EARL OF DUNDONALD'S SPECIFICATION.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ARCHI-
BALD Earl of DUNDONALD, send greeting.
WHEREAS His most Excellent Majesty King George the Third, by
His Letters Patent under the Great Seal of Great Britain, bearing date
5 at Westminster, the Thirtieth day of April, in the twenty-first year of
His reign, did give and grant unto me, the said Archibald Earl of Dun-
donald, His especial licence, full power, sole priviledge and authority, that I,
the said Archibald Earl of Dundonald, my exors, adñññors, and assigns, should
and lawfully might, during the term of years therein expressed, make, use,
exercise, and vend, within that part of His Majestie's Kingdom of Great
Britain called England, His Dominion of Wales, an Town of Berwick-
upon-Tweed, my Invention of "A METHOD OF EXTRACTING OR MAKING TAR,
PITCH, ESSENTIAL OILS, VOLATILE ALKALI, MINERAL ACIDS, SALTS, AND CINDERS,
FROM PIT COAL;" in which said recited Letters Patent is contained a proviso
obliging me, by an instrument in writing under my hand and seal, particularly
to describe and ascertain the nature of my said Invention, and in what manner
the same is to be performed, to be inrolled in His Majestie's High Court of
Chancery within four calendar months after the date of the said Letters
Patent, as in and by the said Letters Patent, relation being thereunto had,
may more at large appear.

page_text: NOW KNOW YE, that in compliance with the said proviso, I, the said
Archibald Earl of Dundonald, do hereby declare that the nature of my said
Invention, and the manner in which the same is to be performed, is described
and ascertained in manner following, that is to say :-
The method I have invented for the extracting of tar, pitch, essential oils,
volatile alkalies, mineral acids, and salts, and the making of cinders, from pit
coal, consists in admitting the external air to have a passage or passages
through the vessells or buildings in which the coal from which any of the
above substances are to be distilled is put, whether by itself or along with
limestone, flints, iron ore, bricks, or any other substance, by which means the
said coals after being kindled are enabled, by their own heat and without the
assistance of any other fire, to throw off in distillation or vapour the tar, oil,
alkalies, acids, and salts they contain into receivers or condensing vessells
communicating with the vessells or buildings containing the coals, and at the
same time of wasting, caleining, or burning any substances that may be mixed
with them. It appears to me necessary, lest others encroach upon my Patent, to
describe as above the principle upon which I act, in as few words as possible,
and in such a manner as will admit of no ambiguity; therefore, according to
what is above set forth and declared, persons who shall extract tar, &c. from
pit coal in vessells or buildings, it matters not their shape or size, whereby the
coals are made to burn or igniate without flaming by a regulated admission of the
external air thro' different appertures in the buildings, so as by their own heat
to throw off the tar, oils, &c. that they contain,-persons who do so without my
.permission are deemed to encroach upon my Patent, as the only method used or
known, until my new discovery, was a distillation of coal in close vessells, where
the admission of the external air was prevented, and where other fuel or coals
were required besides the coals contained in the close vessell to produce the
heat necessary to pervade the same, and to cause the coals contained therein
to throw off the tar, oils, &c. that they contained. I do not think it anyways
of moment to subjoin any drawings of the buildings or kilns that may be
used according to my new Invention for the making of tar, &c., because these
buildings may be made either square, circular, or oval, as fancy may direct,
the art depending upon the management of the air admitted into the kilns,
which can only be acquired by experience; and as it is by no means meant to
keep the manufacture hid or concealed, those who want to see the practical
part will have an opportunity so to do at the different places where the manu-
facture is to be carried on. Exclusive of the above Invention, for which only the
Patent has been obtained, I promote the condensation of the less coercible
part of the vapour that comes off in distillation by commixing it with the

page_text: steam of boiling water, and compleat the condensation by the means of cold
water, either in contact with the vapour, or applied externally to the vessells
through which it passes; and by an admission of the external air into the
condensing vessells when needful, I also cause the vapour to pass through
more condensing vessells than one, to separate by that means the different oils
and substances according to the different degrees of cold and moisture requisite
to condense them; or occasionally I follow the usual and common modes in
practice for condensing the vapours thrown off from any substances by the
action of heat.
In witness whereof, I have hereunto set my hand and seal, this Eighth
day of August, in the year of our Lord One thousand seven hundred
and eighty-one.
Sealed and delivered, being first duly
stampt, in the presence of
H. G. RIDPATH.
JAMES HENDERson.
DUNDONALD. (L.S.)
AND BE IT REMEMBERED, that on the Eighth day of August,
in the year of our Lord 1781, the aforesaid Earl of Dundonald came before
our said Lord the King in His Chancery, and acknowledged the Specification
aforesaid, and all and every thing therein contained and specified, in form
above written. And also the Specification aforesaid was stampt according
to the tenor of the Statutes made in the sixth year of the reign of the late King
and Queen W and Mary of England, and so forth, and in the seventeenth
year of the reign of His Majesty King George the Third.
Inrolled the Twentieth day of August, in the year of our Lord One
Inrolled the Twentieth day of August, in the year of our Lord One
thousand seven hundred and eighty-one.