IMPROVEMENTS IN
Year: 1873

page_text: LETTERS PATENT to Charles Caspers, of Newcastle-on-Tyne, in tho
County of Northumberland, for the Invention of "IMPROVEMENTS IN
D Dan
Scaled the 8th July 1873, and dated the 9th May 1873.
PROVISIONAL SPECIFICATION left by the said Charles Caspers at the
Office of the Commissioners of Patents, with his Petition, on the
9th May 1873.
I, CHARLES CASPERS, of Newcastle-on-Tyne, in the County of North-
umberland, do hereby declare the nature of the said Invention for
"IMPROVEMENTS IN THE PURIFYING OF CRUDE ANTHRACENE OF COMMERCE," to be
as follows:-
This Invention has for its object improvements in the purifying of
crude anthracene of commerce produced from the distillation of coal tar
by the separation of impurities from it. For this purpose I take the

page_text: crude anthracene, from which the oily matter has been separated so far
as it can be done by pressure, centrifugal force, or other mechanical
means, and I treat it, first, by mixing it with about its own weight or
more of some light tar oil, naphtha, crude benzole, mineral oil, or other
light oils, such as paraffin oils, ligroine, and such like oils or spirits, or
methylated spirits, as may be most economical and suitable, at a tem-
perature of about 12 to 15 degrees centigrade, and I stir it up well until
all solid matters are reduced to small atoms. The result is that the light
oils dissolve a great portion of the impuritics, such as napthaline,
phenole, cresole, and other matters which I wish to get rid of from the
crude anthracene, but the anthracene itself does not dissolve (or at
most a very small portion of it dissolves), so long as the temperature is
kept at about 15 degrees centigrade or under. I then let the mixture
settle, so that the undissolved portion falls to the bottom. I take a
sample of the sediment, and if I find this sediment is comparatively
pure, for instance, if it contains about 70 to 80 per cent. of anthracene,
I cither filter it or I run off the liquid from the top so as to obtain the
sediment as free as possible from liquid matter, and I wash it again as
often as necessary with fresh light oils as before and collect the sediment
again, and I then give it a final washing with spirit, using by preference
methylated spirit. I then press the sediment so as to extract out of it
by mechanical means as much as possible of the liquid. I then heat it
slowly and keep it for some time at about 100 degrees centigrade so as
to dry it thoroughly, and then perfectly dry anthraceno remains in a
comparatively pure state, and probably containing about 85 to 90 per
cent. of pure anthracene and melting at 190 degrees centigrade or
upwards. This I call my anthracene of the third quality.
In the process of producing this anthracene of the 3rd quality, if on
obtaining the first sediment as before described, after running off the
liquid or filtering it from the sediment I find that the sediment contains
matters which melt at a higher temperature than anthracene, such as
chrysene, pyrene, and benzerythrene, I then run off the liquid from the
top so as to leave the sediment, which I then mix with a 2nd quantity
of light oils or spirits in the same manner as before, and after stirring it
for a short time I heat it carefully and slowly until all the anthracene is
dissolved; it will dissolve at or before the time of boiling. I then cool
it gradually to 12 or 15 degrees centigrade, and when cold the anthra-

page_text: cene is precipitated to the bottom in a comparatively pure state, and the
oil retains in a dissolved state most of the above impurities. I then
either filter it or run the liquid off so as to leave the sediment behind,
and (if necessary) I wash this sediment again as often as necessary with
fresh light oils or spirit as before; and for the last washing I use a spirit
by preference using methylated spirits. After collecting the sediment I
press it so as to extract out of it by mechanical means as much as
possible of the liquid. I then heat it slowly, and keep it for some time
at about 100 degrees centigrade as as to dry it thoroughly, and when
perfectly dry anthracene in a comparatively pure state remains, con-
taining about 85 to 90 per cent. of pure anthracene, melting at about
190° centigrade or upwards, about the same in quality as I have before
called my 3rd quality of anthracene.
If I wish to make still purer anthraceno I take a quantity of my 3rd
quality of anthracene and I heat it in a vessel until it fuses, which it
will do at about 190 degrees centigrade or upwards, and I continue to
heat it up to about 205 degrees centigrade and then allow it to cool
slowly. By heating it thus I get rid of all or nearly all of those hydro-
carbons, which melt and evaporate at a lower temperature than about
205 degrees centigrade, and any spirit or light oil remaining will be
evaporated off when it has cooled; a hard crystallised mass remains,
which has a dark green color, and which contains about 95 to 97 per
cent. pure anthracene. This is what I call my 2nd quality of anthracene.
If I wish to purify it still further I sublime it in a closed retort, and
the product consists of small white or light yellow leafy crystals, which
I call my first quality of pure anthracene.
None of these three qualities of anthracene have hitherto been intro-
duced into commerce in this country.
I utilize all the light oils and spirits which I have used in the before-
named processes by distilling them and thus rendering them fit to be
used again, and the anthracene, if any, which is left behind can also be
extracted.
In treating the crude anthracene in the preparation of my anthracene
of the third quality, if I find it is mixed with coal dust, carth, wood, or
other matters which are insoluble in the light oils or spirits used in the

page_text: processes before described I get rid of them by an additional filtration
of the liquid while it is hot and while the anthracene is dissolved in the
light oils or spirits, as above mentioned.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Charles Caspers in the Great Seal Patent Office
on the 8th November 1873.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, CHARLES
CASPERS, of Newcastle-on-Tyne, in the County of Northumberland, send
greeting..
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Ninth day of May, in the year of our
Lord One thousand eight hundred and seventy-three, in the thirty-
sixth year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said Charles Caspers, Her special license
that I, the said Charles Caspers, my executors, administrators, and
assigns, or such others as I, the said Charles Caspers, 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 PURIFYING OF CRUDE ANTHRACENE OF COMMERCE," upon the condition
(amongst others) that I, the said Charles Caspers, my executors or
administrators, by an instrument in writing under my, or their, or one
of their hands and scals, should particularly describe and ascertain the
nature of the said Invention, and in what manner the same was to be
performed, and cause the samo 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 Charles Caspers, do hereby declare
the nature of the said Invention, and in what manner the same is to bo
performed, to be particularly described and ascertained in and by the
following statement thereof, that is to say :-
Crude antiracene, either impressed (which is then usually called

page_text: green oil, and contains from 5 to 10 per cent. of pure anthracene) or
pressed (in which case it contains from 15 to 25 per cent of puro
anthracene), contains hydrocarbons, both liquid and solid, such as
napthaline, acetyl napthaline, fluorenc, phenanthrene, which fuse at a
lower temperature than anthracene, as well as other hydrocarbons which
melt at a higher temperature, such as chrysene, pyrene, and others, and
it also contains acids, as phenole, cresole, creosote, &c., which should
all be separated from the crude anthracene in order to obtain puro
anthracene (CH). Pure anthracene being the only produce from
coal tar which can be used for the manufacture of the coloring matter
called "alizarine."
This Invention has for its object improvements in the purifying of
crude anthracene of commerce, produced from the distillation of coal
tar by the separation of impurities from it. For this purpose I tako
the crude anthracene from which the oily matter has been separated so
far as it can be done by pressure, centrifugal force, or other mechanical
means, and after having ascertained the amount of pure anthracene
which it contains by the usual spirit or bi-sulphide of carbon test, I treat
it first, by mixing it with a proportionate quantity (according to the
amount of pure anthracene which it contains) of some light tar oil,-
benzole, naphtha, or other light oils, such as petroleum, naphtha,
paraffine oils, ligroine, and such like oils, or spirits, or bi-sulphide of
carbon, as may be most economical and suitable at a temperature of
about 12 to 15 degrees centigrade, and I stir it up well until all solid
matters are reduced to small atoms. The result is that the light oils
dissolve a great portion of the above impurities which I wish to get
rid of from the crude anthracene, but the anthracene itself does not
dissolve (or at most a very small portion of it dissolves) so long as the
temperature is kept at about 15 degrees centigrade or under. I then
let the mixture settle, so that the undissolved portion falls to the
bottom. I take a sample of the sediment and if I find this sediment
is comparatively pure, for instance, if it contains about 70 to 80 per
cent. of anthracene, I either filter it or I run off the liquid from the top
so as to obtain the sediment as free as possible from liquid matters, and
I wash it again as often as necessary with fresh light oils, as before,
and collect the sediment again; and I then give it a final washing with
methylated spirit. I then press the sediment so as to extract out of it

page_text: by mechanical means as much as possible of the liquid. I then heat
it slowly and keep it for some time at about 100 degrees centigrade,
so as to dry it thoroughly, and then perfectly dry anthracenc remains
in a comparatively pure state and probably containing about 85 to 90
per cent. of pure anthracene, and melting at 190° centigrade or upwards.
This I call my anthracene of tho third quality.
In the process of producing this anthraceno of the third quality, if
by testing the crude anthracene by the usual spirit or bi-sulphide of carbon
test I find that the melting point of the residue exceeds 212° centigrade,
which proves the presence of matters which melt at a higher tem-
perature than anthracene, such as chrysene, pyrene, and benzerythrene.
I then rectify the crude anthracene by a complete distillation, which I
regulate in the usual way of distilling coal tar, and endeavour to keep
the different oils separate, so as to obtain the anthracene in a com-
paratively purer state by keeping the heavy green oils separate from the
light oils; but at the temperature of 360 to 370° centigrade I stop
the distillation, and all that remains in the still is a composition of
hydrocarbon which melts at a higher temperature, as before stated,
and by the above process I have got rid of it. From the heavy oils
thus obtained I separate the sediment by filtration, pressure, or other
mechanical means, and after that by washing it and treating it in the
same way as is above described in the manufacture of my anthracene
of the third quality, and after it is dried anthracene remains containing
about 85 or 90 per cent. of puro anthracene, the same as what I have
before described as my anthracene of the third quality.
In case I have to treat crude anthracene of a gummy or sticky
nature, which cannot be filtered and from which the oil cannot be
pressed out, I prefer in the first place to mix it with a suitable quantity
of light oils or spirits in the same manner as before explained, and after
stirring it for a short time I heat it carefully and slowly until all the
anthracene is dissolved; it will dissolve at or before the time of cooling.
I then cool it gradually to 12 or 15 degrees centigrade, and when cold
the anthracene is precipitated to the bottom in a comparatively pure
state, and the oil retains in a dissolved state most of the above
impurities. I then either filter it or run the liquid off so as to leave the
sediment behind, and I wash this sediment again as often as necessary
with fresh light oils or spirits, as before, and for the last washing I

page_text: use methylated spirit. After collecting the sediment I press it so as to
extract out of it by mechanical means as much as possible of the liquid.
I then heat it slowly and keep it for some time at about 100 degrees
centigrade, so as to dry it thoroughly, and when perfectly dry an-
thracene in a comparatively pure state remains, containing about 85
to 90 per cent. of pure anthracene, melting at about 190° centigrade
or upwards, about the same in quality as I have before called my third
quality of anthracene. Anthracene thus refined sometimes contains
acids, such as phenole, cresole, creosote, &c., which I neutralize with
a weak solution of caustic soda by boiling the mixture and filtering
while in the hot state, the residue I wash with methylated spirit and
heat in the same way as before described.
.
If I wish to make still purer anthracene I take a quantity of my
third quality of anthracene and I heat it in a vessel until it fuses, which
it will do at about 190° centigrade or upwards, and I continue to heat
it up to 205° to 210° centigrade; I keep it for some time at this
temperature and then allow it to cool slowly. By heating it thus I
get rid of all or nearly all of those hydrocarbons which melt and
evaporate at a lower temperature than about 205 degrees centigrade,
and any spirit or light oil remaining in it will be evaporated off. When
it has cooled a hard crystallized mass remains, which has a dark green
color, and which contains about 95 to 97 per cent. of anthracene;
this is what I call my second quality of anthracene.
purc
If I wish to purify it still further I sublime it in a closed retort,
and the product consists of small white leafy crystals, which I call
my first quality of pure anthracene.
None of these three qualities of anthracene have hitherto been
introduced into commerce in this country.
my
In treating the crude anthracene in the preparation of anthracene
of the third quality if I find it is mixed with coal dust, earth, wood, or
other matters which are insoluble in the light oils or spirits used in the
processes before described I get rid of them by an additional filtration
of the liquid while it is hot, and while the anthracene is dissolved in
the light oils or spirits, as above mentioned.
I utilize all the light oils and spirits which I have used in the before
named processes by distilling them, and thus rendering them fit to be

page_text: be extracted.
Having thus described the nature of my said Invention, and the
manner of performing the same, I would have it understood that I
claim the processes, substantially as herein described, for the purification
of crude anthracene of commerce.
In witness whereof, I, the said Charles Caspers, have hereunto set
my hand and scal, this Sixth day of November, in the year of
our Lord One thousand eight hundred and seventy-three.