IMPROVEMENTS IN THE PREPARATION OF COLORS FROM METALLIC OXIDES.
Year: 1871

page_text: LETTERS PATENT to Alexander Melville Clark, of 53, Chancery Lane,
in the County of Middlesex, Patent Agent, for the Invention of
"IMPROVEMENTS IN THE PREPARATION OF COLORS FROM METALLIC OXIDES.".
-
A communication from abroad by William Jules Samuel Grawitz,
1
PROVISIONAL SPECIFICATION left by the said Alexander Melville
Clark at the Office of the Commissioners of Patents, with his
Petition, on the 22nd May 1871.
I, ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the
County of Middlesex, Patent Agent, do hereby declare the nature of
the said Invention for "IMPROVEMENTS IN THE PREPARATION OF COLORS FROM
METALLIC OXIDES," to be as follows:-
I prepare the colors in question by calcining at a bright red heat, in a
suitable recipient, the double sulphates expressed by A. 1* O*3 SO + MO,
80' + water, MO representing a metallic protoxide.

page_text: These double sulphates are obtained in the following manner :-1st,
by mixing a solution of sulphate of alumina and of the sulphate of the
metallic oxide, and then crystallizing the same; 2ndly, by decomposing
ammonia alum by means of an oxide, or a salt of such oxide by the aid
of heat, and then filtering the same after it is recovered by means of
water.
By employing an excess of ammonia alum the filtration may be
dispensed with and the calcination effected direct at a bright red heat,
by which a colored product is obtained intimately mixed with a varying
proportion of white alumina, thus permitting of the depth of the color
being regulated at the will of the operator.
The aluminates may also be obtained by the wet process by precipi-
tating insoluble metallic aluminates by adding a solution of aluminate
of soda or of potash to a solution of a metallic salt.
With ocholt this method produces a series of blues
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Alexander Melville Clark in the Great Seal Patent
Office on the 21st November 1871.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ALEXANDER
MELVILLE CLARK, of 53, Chancery Lane, in the County of Middlesex,
Patent Agent, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-second day of May, in the year
of our Lord One thousand eight hundred and seventy-one, in the thirty-
fourth year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto me, the said Alexander Melville Clark, Her special
licence that I, the said Alexander Melville Clark, my executors, adminis-
trators, and assigns, or such others as I, the said Alexander Melville
Clark, 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 PREPARATION OF COLORS FROM METALLIC OXIDES," a
communication to me from abroad by William Jules Samuel Grawitz,

page_text: of Marseilles (Bouches du Rhône), France, upon the condition (amongst
others) that I, the said Alexander Melville Clark, 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 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 Melville Clark, 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 (that is to say) :—
The colors are produced by the combination of the sesquioxide of
aluminum, of iron, chromium, manganese, or uranium with a coloring
protoxide in either of the following ways :-
:―
1st. Double sulphates similar to alums are formed by mixing con-
centrated solutions of the sulphate of the sesquioxide and of the sulphate
of the protoxide to be combined. This mixture is then crystallized, and
the crystals are dried and calcined at a bright red heat in order to
eliminate the sulphuric acid, the residue obtained consisting of sesquioxide
combined with the protoxide.
2ndly. The ammonia alums of chromium, iron, manganese, uranium,
or aluminum are dissolved in a suitable receptacle together with the
protoxide with which they are to be combined or with a salt of such
protoxide. The solution is evaporated to dryness, during which the
ammonia is evolved and the residue is calcined at a bright red heat in
order to eliminate the sulphuric acid. The residue consists of sesquioxide
combined with the protoxide. Potassa or soda alums will also furnish
analogous products.
3rdly. These coloring matters may be prepared by adding the soluble
alkaline aluminates and chromites to a salt of the protoxide in solution.
By double decomposition an aluminate or chromite of the protoxide will
be formed, which is to be afterwards dried and calcined.
Instead of combining the sesquioxide of aluminum, or of iron, chro
mium, uranium, or manganese equivalent for equivalent of the protoxide,
there may be a less quantity of protoxide than would correspond with the

page_text: chemical equivalent, whereby the depth of color of each compound may
be varied.
Furthermore, one of the five sesquioxides above cited may be combined
in a similar manner with several protoxides simultaneously for the
purpose of varying the tint of the compound. For example, by calcining
one equivalent of ammonia alum with one equivalent of oxide of cobalt
aluminate of cobalt A 13 Os Co. O is obtained. By employing an excess
of alum an aluminate A. 1° 0° Co O is obtained mixed chemically with
a varying proportion of white alumina, by the aid of which the shade
of color may be regulated at will. By adding nickel the color may be
changed to green. The same remarks apply to the other sesquioxides
and protoxides.
The above-mentioned colors produced in the manner herein described
are applicable for all kinds of painting and for printing on paper or
fabrics.
The foregoing is a description of the processes and products which I
claim and desire to secure Letters Patent.
In witness whereof, I, the said Alexander Melville Clark, have
hereunto set my hand and seal, this Twentieth day of November,
in the year of our Lord One thousand eight hundred and seventy-
one.