Iж- PROVEMENTS IN THE TREATMENT OF AMMONIACAL LIQUOR OF GAS WORKS TO OBTAIN THEREFROM SALTS OF AMMONIA
Year: 1869

page_text: LETTERS PATENT to Alexander Angus Croll, of Coleman Street,
in the City of London, Civil Engineer, for the Invention of "Iж-
PROVEMENTS IN THE TREATMENT OF AMMONIACAL LIQUOR OF GAS WORKS TO
OBTAIN THEREFROM SALTS OF AMMONIA."
Sealed the 3rd June 1870, and dated the 11th December 1869.
PROVISIONAL SPECIFICATION left by the said Alexander Angus Croll
at the Office of the Commissioners of Patents, with his Petition,
on the 11th December 1869.
I, ALEXANDER ANGUS CROLL, of Coleman Street, in the City of
London, Civil Engineer, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN THE TREATMENT OF AMMONIACAL LIQUOR OF
GAS WORKS TO OBTAIN THEREPROM SALTS OF AMMONIA," to be as follows:-
According to one arrangement the ammoniacal liquor is supplied to
one of, by preference, two or more closed boilers, and thence from the
first to the second and so on of these boilers, which are heated to cause
the ammonia to pass off in the form of vapour from one to the next, and

page_text: then from the last of them by a suitable passage by which such vapour
is conducted to below the surface of sulphuric acid contained in a
suitable chamber, which chamber is also supplied with cold ammoniacal
liquor so as to keep down the temperature of the acid in this chamber,
say to about 180 degrees Fahrenheit. The vapour of ammonia from the
boiler, the cold ammoniacal liquor, and the sulphuric acid are, by
preference, conducted together into this chamber. This chamber is
sealed so that the sulphuretted hydrogen evolved may be conducted
away to be burned and utilized in the manufacture of sulphuric acid or
otherwise as may be desired whilst the liquid in a neutral state flows
therefrom in succession to a series of shallow evaporating troughs or
pans, each succeeding one being placed somewhat below that preceding
to facilitate the flow from each to the next. These pans are heated so
that the last of the series receives the greatest heat and the first of them
the least. From the last of these pans the liquid if not sufficiently
concentrated to crystalize when cool may flow into an open boiler or
trough kept at the boiling point, by preference by steam, and when the
liquor is at a crystallizing point it is allowed to flow into a cooling vessel
from which the sulphate of ammonia obtained is fished into a dripping
stage, or it may be placed in a centrifugal machine to dry by the
removal of the liquor not sufficiently strong to crystalize.
According to another arrangement the ammoniacal liquor from gas
works is supplied to a closed boiler heated to cause the liquor to pass
off in the form of vapour by a suitable passage to a vessel containing
sawdust saturated with sulphuric acid and thence to other vessels in
succession similarly provided, each of these vessels is formed with a
chamber at the lower part thereof which is separated from the upper by
a perforated partition. The ammoniacal vapour in each case passes first
into the lower chamber and thence through the perforations of the
partition forming the cover of that chamber into the chamber above
containing the saturated sawdust, through which it passes becoming in
its passage in part absorbed by the acid held by the sawdust. The
ammoniacal vapour from the first vessel passes away therefrom at the
upper part thereof to a similar chamber to that described in the lower
part of the next of them, and so on until the vapour is sufficiently
exhausted of its ammonia. These vessels are by preference surrounded
by a non-conducting jacket so as to retain the temperature of the
vapour as much as possible. The sulphuric acid used is that known as

page_text: 80 per cent. sulphur acid or specific gravity 1 700.. The result is that
the sawdust becomes highly saturated with sulphate of ammonia and' is
highly valuable as a manure or for other purposes. The sulphuretted
hydrogen arising from the process may be burned or otherwise.
Similar results may be obtained when using any of the materials
described in the Specifications of Letters Patent granted to me bearing
date 2nd July 1863, No. 1647, 14th. July 1864, No. 1759, and 18th
November 1864, No.. 2883..
When chlorides are used the salt obtained will be a muriate of
ammonia, and when sulphates or sulphuric acid is used the salt obtained
will be a sulphate of ammonia, the crystals. being readily obtained by
washing as is well understood.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Alexander Angus Croll in the Great Seal Patent.
Office on the 11th June 1870.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ALEXANDER
ANGUS CROLL, of Coleman Street, in the City of London, Civil Engineer,.
send greeting.
December, in the
sixty-nine, in the
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Eleventh day of
year of our Lord One thousand eight hundred and
thirty-third year of Her reign, did, for Herself, Her heirs and. successors,.
give and grant unto me, the said Alexander Angus Croll,. Her special
licence that I, the said Alexander Angus Croll, my executors, adminis-.
trators, and assigns, or such others as I, the said Alexander Angus.
Croll, 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 vond, within the United Kingdom of Great Britain
and Ireland, the Channel Islands, and Isle of Man, an Invention for
"IMPROVEMENTS IN THE TREATMENT OF AMMONIACAL LIQUOR OF GAS WORKS TO
OBTAIN THERE FROM SALTS OF AMMONIA," upon the condition (amongst others);
that I, the said Alexander Angus Croll, 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

page_text: 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 Alexander Angus Croll, 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 following statement thereof, that is to say :-
In proceeding according to my Invention to treat ammoniacal liquor
of gas works in order to obtain therefrom salts of ammonia the
ammonical liquor is according to one arrangement or method supplied
to one of, by preference, two or more closed boilers, and thence from
the first to the second and so on of these boilers, which are heated to
cause the ammonia to pass off in the form of vapour from one to the
next, and then from the last of them by a suitable passage by which
such vapour is conducted to below the surface of sulphurio acid con-
tained in a suitable chamber, which chamber is also supplied with cold
ammoniacal liquor so as to keep down the temperature of the solution
in this chamber, say, to about 200 degrees Fahrenheit though this may
be varied, care being taken that the heat employed shall not be such as
to cause loss of the volatile salts of ammonia. The vapour of ammonia
from the boiler, the cold ammoniacal liquor, and the sulphuric acid are
by preference conducted together into this chamber. This chamber is
sealed so that the sulphuretted hydrogen evolved may be conducted
away to be burned and utilized in the manufacture of sulphuric acid or
otherwise as may be desired whilst the liquid in a neutral state flows
therefrom in succession to a series of shallow evaporating pans, each
succeeding one being placed somewhat below that preceding to facilitate
the flow from each to the next. These pans are heated so that the
last of the series receives the greatest heat, or such as will cause free
ebulition, and the first of them the least heat, care being taken that
this first pan shall not receive a heat that shall raise the liquid to a
temperature higher than about 10 to 15 degrees below the boiling point of
the solution, the object being to employ heat in this first pan less than
that at which the sulphite or other combinations of ammonia are rendered
volatile, and thus conversion of the sulphite into sulphate of ammonia is
accomplished by slow evaporation and exposure to the atmosphere.
From the last of these pans the liquid if not sufficiently concentrated to

page_text: crystallize by fishing out the salt may flow into an open boiler or trough
kept at the boiling point, by preference by steam, and when the crystals
of sulphate of ammonia are formed they are fished out, or when the
liquor is at a crystallizing point it is allowed to flow into a cooling
vessel for crystallization in the usual way, and with the view of still
further obtaining a dry salt, or a salt free from moisture, I place the
salt in a centrifugal machine by which a dry salt is immediately pro-
duced. In employing centrifugal apparatus for this purpose caro
should be taken that the parts exposed to the action of the salt be
coated with metal not extensively acted upon by the salts of ammonia.
According to another arrangement or method the ammoniacal liquor
from gas works is supplied to a closed boiler heated to cause the liquor
to pass off in the form of vapour by a suitable passage to a vessel con-
taining sawdust saturated with sulphuric acid, and thence to other vessels
in succession similarly provided. Each of these vessels is formed with a
chamber at the lower part thereof, which is separated from the upper
by a perforated partition. The ammoniacal vapour in each case passes
first into the lower chamber, and thence through the perforations of the
partition forming the cover of that chamber into the chamber above
containing the saturated sawdust through which it passes, becoming in
its passage in part absorbed by the acid held by the sawdust. The
ammoniacal vapor from the first vessel passes away therefrom at the
upper part thereof to a similar chamber to that described in the lower
part of the next of them, and so on until the vapour is sufficiently
exhausted of its ammonia; or chambers may be employed having in
them trays containing layers of the sawdust saturated as described to be
acted upon by the vapour of ammonia, such trays with their contents
being capable of being changed in succession, so that the tray containing
the freshest material may be that from which the vapour last passes, and
that which has been longest acted on is that which first receives the
vapour, care being taken that the quantity of vapour of ammonia passing
through these chambers in relation to the quantity of material to act on
it be such as fully to absorb the ammonia before the vapour leaves the
chambers. The form of these chambers and the passage therethrough
may be varied. These chambers are by preference surrounded by a non-
conducting jacket so as to retain the temperature of the vapour as much
as possible. The strength of acid and the mode of combining such acid
with sawdust preferred to be used by me, is that described in the

page_text: Specification of Letters Patent granted to me bearing date the 14th of
July 1864, No. 1759. The result is that the sawdust becomes highly
saturated with sulphate of ammonia and is highly valuable as a manure
or for other purposes. The sulphuretted hydrogen arising from the
process may be burned or otherwise.
Similar results may be obtained when using any of the materials
described in the Specifications of Letters Patent granted to me bearing
date 2nd July 1863, No. 1647, and 18th November 1864, No. 2883.
When chlorides are used the salt obtained will be a muriate of ammonia,
and when sulphates or sulphuric acid is used the salt obtained will be a
sulphate of ammonia, the crystals being readily obtained by washing, as
is well understood.
Having thus described my Invention and means which I adopt in
carrying the same into effect, I would have it understood that what I
claim is, the treatment of ammoniacal liquor of gas works to obtain
therefrom salts of ammonia, in manner substantially as described.
In witness whereof, I, the said Alexander Angus Croll, have here-
unto set my hand and seal, this day of June, in the year
of our Lord One thousand eight hundred and seventy.