IMPROVEMENTS IN THE MANUFACTURE OF PHOSPHATIC MANURES AND SULPHATE OF AMMONIA
Year: 1868

page_text: LETTERS PATENT to Arthur McDougall, of the Firm of McDougall,
Brothers, of the City of Manchester, Manufacturing Chemists, for
the Invention of "IMPROVEMENTS IN THE MANUFACTURE OF PHOSPHATIC
MANURES AND SULPHATE OF AMMONIA."
Sealed the 14th May 1869, and dated the 18th November 1868.
PROVISIONAL SPECIFICATION left by the said Arthur McDougall
at the Office of the Commissioners of Patents, with his Petition,
on the 18th November 1868.
I, ARTHUR MCDOUGALL, of the Firm of McDougall, Brothers, of
the City of Manchester, Manufacturing Chemists, do hereby declare
the nature of my said Invention for "IMPROVEMENTS IN THE MANUFACTURE
or PHOSPHATIC MANURES AND SULPHATE OF AMMONIA," to be as follows:-
My Invention consists in an improved combination of processes for
the production of soluble superphosphates of lime and sulphate of
ammonia. I take animal charcoal or the substitute for animal charcoal
described below and treat it witli sulphuric acid, and then separate
the sulphate of lime so produced from the solution of acid phosphate

page_text: of lime by filtration or other convenient means. I then agitate this
sulphate of lime with ammoniacal liquor resulting from the destructive
distillation of carbonaceous substances; by this means I obtain sulphate
of ammonia which I separate from its solution by evaporation. I also
evaporate the solution of acid phosphate of lime with a proper proportion
of tribasic phosphate of lime until upon cooling it crystallises as a super-
phosphate suitable for manure or other purposes in the arts.
I also prepare a product which I can use as a substitute for animal
charcoal in the above process by taking substances in a fine state of
division containing phosphate of lime, and mixing with small coal or
pitch or other carbonaceous substances, and submitting the mixture to
the action of heat in closed vessels.
By the foregoing combination of processes I make the sulphuric acid
do double work; first, to produce soluble phosphates and then to unite
with the ammonia contained in the ammoniacal liquor to form sulphate
of ammonia.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Arthur McDougall in the Great Seal Patent Office
on the 18th May 1869.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ARTHUR
M DOUGALL, of the Firm of McDougall, Brothers, of the City of
Manchester, Manufacturing Chemists, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Eighteenth day of November, in the
year of our Lord One thousand eight hundred and sixty-eight, in the
thirty-second year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said Arthur McDougall, Her special license
that I, the said Arthur McDougall, my executors, administrators, and
assigns, or such others as I, the said Arthur McDougall, my executors,
administrators, or 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

page_text: IN THE MANUFACTURE OF PHOSPHATIC MANURES AND SULPHATE OF AMMONIA,"
upon the condition (amongst others) that I, the said Arthur M'Dougall,
my executors or administrators, by an instrument in writing under my
hand and seal, should particularly describe and ascertain the nature
of the 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 Arthur McDougall, do hereby
declare the nature of my said Invention, and in what manner the
same is to be performed, to be particularly described and ascertained
in and by the following statement, that is to say:-
My Invention consists in an improved combination of processes for
the production of soluble superphosphates of lime and of sulphate of
ammonia. I take animal charcoal or the substitute for animal charcoal
described below and treat it with sulphuric acid, and then separate
the sulphate of lime so produced from the solution of acid phosphates
of lime by filtration or other convenient means. I then agitate this
sulphate of lime with ammoniacal liquor resulting from the destructive
distillation of carbonaceous substances; by this means I obtain in
solution sulphate of ammonia which I separate from its solution by
evaporation. The solution of acid phosphate of lime resulting as before
mentioned is evaporated with a proper proportion of tribasic phosphate
of lime, until upon cooling it crystallises as a superphosphate suitable
for manure or other purposes in the arts.
I also prepare a product which I can use as a substitute for animal
charcoal in the above process by taking substances in a fine state of
division containing phosphate of lime and mixing with small coal or
pitch or other carbonaceous substances, and submitting the mixture
to the action of heat in closed vessels; or I can introduce carbonaceous
substances of light specific gravity and of porous nature, such as ground
wood charcoal, into the vat, either before or after having heated the
phosphate with vitriol, and thus obtain a product upon which the
operation of filtration can be easily performed.
By the foregoing combination of processes I make the sulphuric
acid do double work; first, to produce soluble phosphates, and then to
unite with the ammonia contained in the ammoniacal liquor to form
sulphate of ammonia.

page_text: I will now proceed to describe a method by which the Invention may
be carried into operation. I introduce into wooden vats lined with lead
and provided with a set of stirrers or agitators driven by power or
otherwise a quantity of vitriol equal to one ton of the strongest oil of
vitriol, and mix it with hot water until the vat is about two-thirds full
and is of specific gravity about twelve degrees Baumé; I then gradually
add about twenty-five hundredweight of the animal charcoal in fine
powder. The agitators are kept in constant motion for about ten hours,
and then the whole contents of the vat are let off into a large woollen
filter where the liquid is separated from the solid matter and the last
portions of the liquor removed by repeated washings with hot water.
The liquid thus obtained contains an acid phosphate of lime, and I
evaporate the same in cast-iron pans coated with enamel or other
convenient vessels with the addition of tribasic phosphate of lime until
I find that upon cooling the contents of the pan will solidify (into a
mass of crystals). I add 0.64 ounces of the tribasio phosphate per
gallon for each degree of strength of Baumé's hydrometer at which
the phosphate liquor stands; it is then poured into a stone or other
tank and occasionally stirred until cool and is then dried upon a warm
floor. The contents of the filter after the phosphates have been washed
out with water consists of sulphate of lime in a very fine porous state
mixed with carbon; this gives the mass a very light porous nature,
enabling the process of filtration to be carried on rapidly and thoroughly.
This filter residue is now removed into a large wooden vat provided
with agitators and mixed with such a proportion of ammoniacal liquor
resulting from the destructive distillation of carbonaceous substances as
that the sulphate of lime shall be sufficient to decompose the carbonate
of ammonia contained in the ammoniacal liquor. The agitators are kept at
work for about two hours, and then the contents of the vat are discharged
into a filter, when a solution chiefly consisting of sulphate of ammonia
results. To this solution which may be found to be slightly alkaline,
vitriol is added until the solution becomes very slightly acid, the liquor
is then to be evaporated until it is sufficiently concentrated and yields a
crop of crystals of sulphate of ammonia on cooling. To the residue
remaining in the filter water is poured in order to wash out the sulphate
of ammonia, and the last portions are removed therefrom by submitting
the same in bags to powerful pressure in a hydraulic or other powerful
press.
Having now described and particularly ascertained the nature of my

page_text: said Invention, and the manner in which the same is or may be used
or carried into effect, I would observe in conclusion that what I
consider to be novel and original, and therefore claim as the Invention
secured to me by the herein-before in part recited Letters Patent is,-
First. The manufacture of phosphatic manures from animal charcoal
or from substitutes therefor by firstly submitting the same to the action
of sulphuric acid, and secondly, the employment of the acid phosphate of
lime resulting therefrom in conjunction with tribasic phosphate of lime,
as herein-before described.
Second. The obtaining of sulphate of ammonia by the decomposition
of the residual sulphate of lime resulting from the action of phosphate
of lime of sulphuric acid by the employment of the ammoniacal liquors
herein referred to.
In witness whereof, I, the said Arthur McDougall, have to this
my Specification set my hand and seal, this Fifteenth day of May
One thousand eight hundred and sixty-nine.
ARTHUR MCDOUGALL. (L.S.)