IMPROVEMENTS IN WORKING UP CERTAIN WASTE SULPHATES AND NITRATES, AND FOR THE MANUFACTURE OF USEFUL PRODUCTS THEREFROM
Year: 1854

page_text: LETTERS PATENT to John Lang Dunn, of Glasgow, in the County of
Lanark, Manufacturing Chemist, for the Invention of "IMPROVEMENTS
IN WORKING UP CERTAIN WASTE SULPHATES AND NITRATES, AND FOR THE
MANUFACTURE OF USEFUL PRODUCTS THEREFROM."
Sealed the 12th June 1855, and dated the 27th December 1854.
PROVISIONAL SPECIFICATION left by the said John Lang Dunn at the
Office of the Commissioners of Patents, with his Petition, on the
27th December 1854.
I, JOHN LANG DUNN, of Glasgow, in the County of Lanark, Manufacturing
Chemist, do hereby declare the nature of the Invention for "IMPROVEMENTS IN
WORKING UP CERTAIN WASTE SULPHATES AND NITRATES, AND FOR THE MANUFAC-
TURE OP USEFUL PRODUCTS THEREFROM," to be as follows:-
There being quantities of nitrate of copper and nitrate of iron obtained as
waste products in the etching of printing rollers, &c., and also sulphate of lead
obtained from the chemical combinations attending certain of the operations
of calico printing, I treat those nitrates and sulphates after the following
manner:
Supposing it to be nitrate of copper that is to be treated, I add, after suffi-
ciently diluting with water, a proportionate quantity of litharge, and apply heat;
after a time the liquor is drawn off, and the residuum is boiled and partly

page_text: added to the liquor before drawn off; this is again diluted, and metallic lead
added, and the copper contained in the liquor is deposited by electrical agency
and separated. The original liquor, when quite freed from copper, is evaporated
in the usual manner to obtain crystallized nitrate of lead.
If the substance to be treated is nitrate of iron, I saturate the liquor with
ammonia and filter it; I then obtain nitrate of ammonia by evaporating
and crystallizing, and I dry and otherwise prepare the peroxide of iron for
paints, &c.
If sulphate of lead is the substance operated upon, I proceed, in the first
place, to convert it into sulphuret by calcination with charcoal, and then into
nitrate by addition of nitric acid.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said John Lang Dunn in the Great Seal Patent Office on the
26th June 1855.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
LANG DUNN, of Glasgow, in the County of Lanark, Manufacturing Chemist,
send greeting.
any
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-seventh day of December, in the year of our
Lord One thousand eight hundred and fifty-four, in the eighteenth year of
Her reign, did, for Herself, Her heirs and successors, give and grant unto me,
the said John Lang Dunn, Her special licence that I, the said John Lang
Dunn, my exccutors, administrators, and assigns, or such others as I, the
said John Lang Dunn, my executors, administrators, and assigns, should at
time agree with, and no others, from time to time and at all times there-
after 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
WORKING UP CERTAIN WASTE SULPHATES AND NITRATES, AND FOR THE MANUFAC-
TURE OF USEFUL PRODUCTS THEREFROM," upon the condition (amongst others) that
I, the said John Lang Dunn, 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.

page_text: NOW KNOW YE, that I, the said John Lang Dunn, 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) :-
There being quantities of nitrate of copper and nitrate of iron obtained as
waste products in the etching of printing rollers and other printing surfaces,
and also sulphate of lead obtained from the chemical combinations attending
certain of the operations of calico printing, I treat those nitrates and sulphates
in the following manner :-
In the case of nitrate of copper, I take the acid, after it has been used for
etching surfaces of copper, and place it in a wooden vat, and dilute it with
water until it marks 56° of Twaddell; I then add litharge to the extent of half
the weight of the diluted liquid, that is to say, if there is 1 cwt. of liquid I
add 56 lbs. of litharge. This mixture is allowed to stand about a week, and
it should be stirred up about a dozen times each day. I prefer heating this
mixture by steam, which I blow into the vat through a wooden tube, by which
means the process is accelerated. When a white deposit of nitrate of lead
forms round the side of the vat, this part of the process is complete. The liquid
is now drawn off by a syphon into another vat, and any litharge which remains
is worked up by the next quantity of liquor operated on. Molten lead, in
quantity equal to that of the litharge used in the first process, is added to the
clear liquid which has been syphoned off. After a few days the liquid becomes
of a light straw color. The precipitated copper is removed and washed, and
may be sold as copper, or re-dissolved to form its salts; the liquid is evaporated,
and the nitrate of lead obtained in crystals in the usual manner. Any metallic
lead left is dissolved in the next liquor added to the vats.
In the case of nitrate of iron, I take the acid which has been employed for
etching surfaces of iron, and I add thereto strong liquid ammonia in excess.
The precipitated oxide of iron is freed from nitrate of ammonia by filtration
and washing, and when dried may be used for painting. The nitrate of
ammonia is crystallized in the ordinary manner.
In the case of sulphate of lead, I take the sulphate as it is obtained as a
waste product from certain of the operations of calico printing, and I dry the
same and mix it with one-sixth part of its weight of ground coal; then I
bring the mixture to a dull red heat in a reverberatory furnace, by which the
sulphate of lead becomes converted into sulphuret. It is then withdrawn from
the furnace, and dissolved in one-third of its weight of nitric acid, and the
nitrate of lead thus formed is crystallized in the usual manner.
Having thus described the nature of my Invention, and the manner of

page_text: performing the same, I would have it understood that I do not confine myself
to the exact details described; but what I claim is, the working up the waste
sulphates and nitrates before mentioned, and obtaining useful products there-
from, as before described.
In witness whereof, I, the said John Lang Dunn, have hereunto set my
hand and seal, this Twenty-fifth day of June, in the year of our
Lord One thousand eight hundred and fifty-five.
цего
from, as before described.
In witness whereof, I, the said John Lang Dunn, have hereunto set my
hand and seal, this Twenty-fifth day of June, in the year of our
Lord One thousand eight hundred and fifty-five.
Witness,
GEORGE LYALL,
267, Argyle St., Glasgow.
JOHN LANG DUNN. (L.S.)