FoB COATING WITH A METAL THE SURFACE OF ARTICLES FORMED OF COPPER OR COFFER ALLOYS, OR IRON WROUGHT OR CAST
Year: 1846

page_text: HOWELL'S
CATION
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, GroRax
HOWELL, of Number Four, Lark Hall Lane, Clapham, in the County of
Surrey, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent under the Great Seal of the United Kingdom of Great Britain and
Ireland, bearing date at Westminster, the Twenty-ninth day of January, in
the ninth year of Her reign, did give and grant unto me, the said George
Howell, my executors, administrators, and assigns, Her especial license; full
power, sole privilege and authority, that I, the said George Howell, my
executors, administrators, and assigns, and such others as I, the said George
Howell, 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 of years therein mentioned, should and lawfully might make, use,
exercise, and vend, within that part of the United Kingdom of Great Britain
and Ireland called England, the Dominion of Wales, and the Town of Berwick-
upon-Tweed, my Invention "FoB COATING WITH A METAL THE SURFACE OF
ARTICLES FORMED OF COPPER OR COFFER ALLOYS, OR IRON WROUGHT OR CAST;"
in which said Letters Patent there is, amongst others, contained a provisn
that if I, the said George Howell, should not particularly describe and ascertain
the nature of my said Invention, and in what manner the same is to be per.
formed, by an instrument in writing under my hand and seal, and cause the
same to be enrolled in Her said Majesty's High Court of Chancery within six
calendar months next and immediately after the date of the said recited Letters

page_text: Patent, that then the said Letters Patent, and all liberties and advantages
whatsoever thereby granted, should utterly cease, determine, and becoine
void, as by the said Letters Patent, reference being thereunto had, will more
fully and at large appeur.
NOW KNOW YE, that in compliance with the said proviso, I, the said
George Howell, do hereby declare that the nature of my Invention, and in
what manner the same is to be performed, is to be particularly described
and ascertained in and by the following statement (that is to say):-
My Invention relates to the covering or coating with platinum the surface
of articles of copper or copper alloys, or iron wrought or cast, and is performed
in the following manner:-The platinum is dissolved in aqua regia; the
iridium which the platinum contains forms a black powdor; this powder is
separated by filtration and thrown away. The solution of platinum is then
evaporated to dryness, and after the residue left by evaporation is cooled a
weight of caustic potash, equal to the weight of metallic platinum originally
employed, must be dissolved in water and poured ou the dried salt of platinum.
By this means a precipitate is obtained of an impure yellow colour, sometimes
having a greenish bus, which occurs when the salt of platin (chloride of
platinum) is overheated in being dried by evaporation to such a degree that
the salt is decomposed into proto chloride of platinumn, a result which ought
to be avoided. A solution of oxalic acid, equal in weight to twice the weight
of the metallic platinum which has been dissolved, is then poured on the
precipitate obtained by adding potash as above described, without decanting
the liquor from which it is precipitated. This mixture ought to be boiled until
the whole sediment is dissolved, and until the liquor becomes transparent; a
very small quantity of iridium will be found at the bottom. The solution is
next to be filtered in order to remove this or any other impurities. After
leaving the liquor to cool, caustic potash, three times the weight of the metallic
platinum originally used, is dissolved in water and added to it. Here again a
small sediment is sometimes met with, and experiments shew that this
result ensues when the chloride of platinum is overdried; that sediment
may be left in the solution without doing it any harm. The solution
is now ready for proceeding to platinize copper, copper alloys, or iron
wrought or east. The surface of the metal to be platinized must be well
cleaned by acid, or by the other means usually employed in such operations.
A vessel of glass or earthenware, capable of bolding the article to be
platinized, is to be taken; the vessel having the article in it is then filled
with solution of platinum above described. A pair or more, necording
to the size of the article to be platinized, of Daniell's, Bunzon's, or of
any other suitable battery, is then to be connected by its positive element

page_text: with the article to be platinized (catode), and with the negative pole or element
of the battery a thin plate, or the foil of platinum (anode), is connected and
immersed in the same solution. The platinizing will then begin, and the
surface of the metal immersed in the solution will be whitened, the duration of
the process depending on the thickness of the layer of the platinum intended
to be deposited. Instead of oxalic acid other substances, as tartaric, citric,
and acetic acids, acid oxalate of potash, and acid tartarate of potash, may be
employed to make the solution of the salt of platinum. When one of these
last-mentioned substances is employed instead of oxalic acid, the solution is
made by the same process as above described. Instead of making the salt of
platinum by the addition of caustic potash to the dried salt of platinum, soda
may be substituted for potash in equivalent quantity, or the ready-made double
salt of chlorides of potassium and platinum can be taken. This double salt
dissolves readily in all the above-mentioned substances, but the preparation of
this salt from the solution of chloride of platinum is not so convenient or cheap
as the method first above described. The solutions obtained in any of the
several methods above described and referred to may be applied for platinizing
by the use of a suitable battery.
Having now described in what manner my said Invention is to be per-
formed, I wish it to be understood, that what I claim as the Invention to be
secured to me by the said Letters Patent is, the coating the surface of copper,
copper alloys, and iron wrought or cast, by the platinum deposited from a
solution as above described.
In witness whereof, I, the said George Howell, have hereunto set my
hand and seal, this Twenty-second day of May, in the year of our
Lord One thousand eight hundred and forty-six.
GEO. (L.B.) HOWELL.