IMPROVEMENTS IN THE TREATMENT OF CERTAIN COMPOUNDS OF ALUMINA, AND THE APPLICATION OF THE SAME IN PRINTING, DYEING, TAWING, PAPER MAKING, AND SUCH LIKE PURPOSES
Year: 1855

page_text: LETTERS PATENT to Henry Davis Pochin, of Salford, in the County of
Lancaster, of the firm of Halliday, Pochin, & Co., Manufacturing:
Chemists, for the Invention of "IMPROVEMENTS IN THE TREATMENT OF
CERTAIN COMPOUNDS OF ALUMINA, AND THE APPLICATION OF THE SAME IN
PRINTING, DYEING, TAWING, PAPER MAKING, AND SUCH LIKE PURPOSES."
Sealed the 11th May 1855, and dated the 30th January 1855.
PROVISIONAL SPECIFICATION left. by the said Henry Davis Pochin. at
the Office of the Commissioners of Patents, with his Petition, on the
30th January 1855:
.
I, HENRY DAVIS POCHIN, of Salford, in the County of Lancaster, of the
firm of Halliday, Pochin, & Co., Manufacturing Chemists, do hereby declare
the nature of the said Invention for "IMPROVEMENTS IN THE TREATMENT OF
CERTAIN COMPOUNDS OF ALUMINA, AND THE APPLICATION OF THE SAME IN PRINTING,
DYEING, TAWING, PAPER MAKING, AND SUCH LIKE PURPOSES," to be as follows:-
I take clay composed of various quantities of silica, alumina, iron, and water,
but I prefer that containing about 45 parts of silica, 37 parts of alumina, 3 of
iron, 17:7 of water in 100 parts, which I grind in an ordinary clay mill. This
is subjected for about two hours to the action of heat in a reverbaratory or
other suitable furnace, during which time it is to be well stirred, until the whole
of the water has been evaporated, and the powder brought into a condition to
be easily acted upon by sulphuric acid. This powder is then passed through a

page_text: fine sieve. One ton of it is intimately mixed with twenty-one hundredweight
of sulphuric acid, having a specific gravity of about 1735. This solution is
reduced by the addition of water to a specific gravity of about 1350. It is then
placed in a leaden or other suitable vessel and the steam or fire heat applied,
being well agitated until it is heated to a temperature of 212° Fahrenheit,
when the greater part of the sulphuric acid combines with the alumina of the
clay, causing a violent action: It is then continued at a boiling temperature
for about four hours, to ensure the combination of the whole of the acid with
the alumina. The fire is then withdrawn and the mass allowed to cool. This
compound I term aluminous cake, which contains but little more than the
silica originally in the clay, and the sulphate of alumina formed by the action
of the sulphuric acid, and contains no free sulphuric acid.
I find that this aluminous cake can be advantageously employed for the
purpose of manufacturing the aluminous mordants used by calico printers and
dyers, and in various other processes used by dyers; and in the preparation of
white leather, in the process called tawing; also in the manufacture of paper,
and other useful purposes, as a substitute for alum and the ordinary sulphate
of alumina.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Henry Davis Pochin in the Great Seal Patent Office on
the 18th July 1855.
_ TO ALL TO WHOM THESE PRESENTS SHALL COME, I, HENRY
DAVIS POCHIN, of Salford,. in the..County of Lancaster, of the firm of Halliday,
Pochin, and Company, Manufacturing Chemists, send greeting."
'
WHEREAS. Her most Excellent, Majesty Queen Victoria,, by Her.Letters
Patent, bearing date the Thirtieth day of January, in the eighteenth year of
Her reign, did, for Herself,. Her heirs and successors, give and grant unto me,
the said Henry Davis Pochin, Her special licence that I, the said Henry
Davis Pochin,, my executors; administrators, and assigns, or such..others.as
I,. the said Henry, Davis Pochin, 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 "IMPROVE-
MENTS IN THE TREATMENT OF CERTAIN COMPOUNDS OF ALUMINA, AND THE APPLI-
CATION OF THE SAME IN PRINTING, DYEING, TAWING, PAPER MAKING, AND SUCH
$ 1

page_text: LIKE. PURPOSES," upon the condition (amongst others) that I, the said Henry
Davis Pochin, 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 imme-
diately after the date of the said. Letters Patent. i... 1
NOW KNOW. YE, that I, the said Henry. Davis Pochin, 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: -
I take clay composed of various quantities of silica, alumina, iron, and water,
or clay without iron, when it can be had. I find that I can use with advantage
and economy, that containing about 45 of silica, 87, of alumina, 3 of oxide of
iron, and 17.7 of water in 100 parts. Such, clay I first dry by subjecting it to
heat, so as to get rid of a portion of the moisture, and fit it for grinding, and
then I proceed to grind it to a moderately fine powder in an ordinary clay
mill, or other suitable apparatus for grinding clay. The clay thus prepared I
subject for about two hours to the action of heat, in a reverberatory or other
convenient furnace, during which time it is 'to be well stirred, until the whole
of the water has been evaporated, and the powder brought into a condition to
be easily acted upon by sulphuric acid, which may be known by treating a
small portion of it in a platinum crucible with sulphuric acid of a known
specific gravity, and then subjecting it to heat, and afterwards dissolving it in
a known quantity of water, and ascertaining the specific gravity of the solution,
which should be so high as to indicate the absence of any free or uncombined
sulphuric acid. This powder is then passed through a fine sieve, of about 80
meshes to the square inch. One ton of it is intimately mixed with 21 cwt. of
sulphuric acid, having a specific gravity of about 1735, and afterwards as much
water added as would reduce the specific gravity of the sulphuric acid employed
to about 1350. It is then placed in a leaden or other suitable vessel and
steam or fire heat applied, being well agitated until it reaches a temperature of
212° Fahrenheit, when the greater part of the sulphuric acid combines with
the alumina of the clay, causing a violent action. It is then continued at a
boiling temperature for about four hours, so as to ensure the combination
of the whole of the acid with the alumina. This may be determined by any of
the ordinary tests; but I prefer to use for this purpose a solution of caustic
ammonia, of a known strength, until an alkaline reaction is obtained, which is
shewn by the application of litmus paper to the solution. The fire is then
withdrawn, and the mass removed and allowed to cool. This compound 1 term

page_text: aluminous cake; it contains but little more than the silica originally in the
clay, and the sulphate of alumina formed by the action of the sulphuric acid on
the alumina, and no free or uncombined acid. I employ the aluminous cake,
obtained in manner above described, in the manufacture of the aluminous
mordants used by calico printers and dyers, and in various other processes used
by dyers; and in the preparation of white leather, in the process termed tawing;
also in the manufacture of paper, as a substitute for alum, and the ordinary
sulphate of alumina. And in the application of this aluminous cake for such
purposes it is not necessary to separate the silica and the small excess of clay
which may have been used for the aluminous cake by any of the expensive
processes, such as lixiviation and evaporation, which have hitherto been adopted
in the preparation of the sulphate of alumina of commerce.
In witness whereof, I, the said Henry Davis Pochin, have hereto set
my hand and seal, this Fourteenth day of July, in the year of our Lord
One thousand eight hundred and fifty-five.
HENRY DAVIS POCHIN. (L.S.)