CERTAIN IMPROVEMENTS IN THE DISTILLATION OF TAR AND PITCH
Year: 1846

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, SAMUEL
CLIFT, of West Bromwich, in the County of Stafford, Gentleman, 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 Eighth day of December, in the tenth year of Her reign,
dil, for Herself, Her heirs and successors, give and grant unto me, the said
Samuel Clift, Her especial licence, full power, sole privilege and authority,
that I, the said Samuel Clift, my executors, administrators, and assigns, and
such others as I, the said Samuel Clift, 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 THE DISTILLATION OF TAR AND PITCH;" in which said Letters Patent is
contained a proviso obliging me, the said Samuel Clift, 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,
and to cause the same to be enrolled in Her Majesty's High Court of Chancery

page_text: 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 there-
unto had, will more fully and at large appear.
NOW KNOW YE, that in compliance with the said proviso, I, the said
Samuel Clift, 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)-
My Invention of Certain Improvements in the Distillation of Tar and Pitch
has for its object, the conducting the process of distilling these substances in
such a manner that a larger quantity of oil may be obtained from the tar or
pitch than is generally produced by the ordinary process, and the production of
coke as a new product from the distillation of tar or pitch. According to the
present mode of distillation of the tar is continued until somewhere about
thirty-five or forty per cent. of the tar is distilled over as oil, and the residue of
the tar which then remains in the still when discharged therefrom forms pitch.
But I find that by submitting the tar or the aforesaid pitch in the process of
distillation to a much higher temperature than that heretofore employed, I'
can obtain much larger quantities of oil, and that the residue then left in the
still is not pitch, but a very pure coke, which is now much more saleable than
the pitch, or by stopping the distillation a little sooner I get a substance fit to
be used as a fuel instead of coal. My improvements therefore consist, first, in
either submitting the tar to a much higher temperature, so that a much larger
quantity of oil may be obtained that is now produced, and the residue when
discharged from the still shall not be pitch, but a substance similar to coke, or
fit for fuel; or else, secondly, by again distilling the pitch made according to
the old process at a higher temperature, so as to extract all the oil still
remaining in the pitch, and reducing the residual matter to coke or a
substance applicable as fuel, or the tar and pitch may be mixed together before
it is put into the still, and the oil distilled therefrom. When the distillation is
carried on to the utmost, and at the highest temperature, whereby all the
bituminous matters are driven off, coke is produced as the residue, but if the
distillation is is stopped at a somewhat earlier period, leaving a certain portion
of the bituminous matter in the still or retort (with or rather in) the coke,
then a product is obtained which may be most advantageously used as fuel in
place of coal. For the first part of my process, instead of the usual tar boilers,
I prefer to employ cast-iron cylinders about two feet in diameter and seven feet
long, having doors at each end, and set horizontally, like gas retorts, in brick-
work (the fireplaces and flues being made in the ordinary manner). The tar

page_text: is put into these cylinders and the heat got up gradually, which drives off the
vapour from the tar through a pipe in the top of the cylinder to the conden-
sers, where it condenses as oil, and the heat is continued and gradually increased,
until either the fuel or the coke (as above named) is produced according to
the desire of the manufacturer. Upon the distillation being finished, the fire
is extinguished, and when the cylinders are sufficiently cool, the door at the
end is opened and the fuel or coke drawn out. To the second part, viz,,
the distillation of the pitch (obtained from the tar according to the usual
mode), I can use as stills the usual gas retorts or ovens, but I prefer using
the gas oven or retort invented by my brother Mr. John Clift, of the Pagoda
Gas Works, Birmingham, and called "Clift's Brick Gas Oven." The pitch
is put into the oven, and the vapor passes through the pipe to the condensers,
where it condenses as oil, and the residue remaining in the oven is found on
discharging the oven to be either fuel or coke, according to the length of time
the distillation is continued, and the heighth of the temperature as described
before under the first part. By these processes a very much larger quantity
of oil is obtained from the tar than heretofore. The benefit of my Invention
can also be obtained by mixing up with the tar or pitch, previous to its being
put into the cylinders, retorts, or ovens as aforesaid, either small coal or coke,
peat or sawdust, or other carbonaceous ingredients, either separately or mixed
together, and sometimes and under certain circumstances it may be found
desirable to do so, in which case the coal, &c. would become coked with the
tar and pitch, and the product left in the still will be a coke or fucl of a mixed
nature, but such additions of coal, &c. to the tar or pitch will not prevent the
extra quantity of oil being obtained from the tar or pitch used in the same
manner as though such things had not been previously mixed with the tar or
pitch. As these iron cylinders, gas retorts, and gas ovens are so well known,
and can be made in so many different forms, I have not considered it necessary
to give any Drawing' of them, particularly as I have not invented anything
new in the apparatus, and do not claim any particular form of still or
apparatus.
But what I claim as my Invention of Improvements in the Distillation of Tar
or Pitch is, the submitting the tar or pitch, either separately or in combination,
in the manner as above described, to a much higher temperature than that
heretofore used, whereby a much larger quantity of oil is obtained than is
now produced by the ordinary modes, and the residue when discharged from
the still is not pitch, but either a substance fit for fuel, or a good coke,
according to the will of the manufacturer; but I must observe that, although
the above Invention is chiefly useful for distilling coal or gas tar, yet were a

page_text: larger quantity of tar oil is desired than can be obtained in the ordinary manner,
it is equally useful and applicable for the distillation of the other tars.
In witness whereof, I, the said Samuel Clift, have hereunto set my
hand and seal, this Eighth day of June, in the year of our Lord Onc
thousand eight hundred and forty-seven.