IMPROVE- MENTS IN COATING OR COVERING METALS WITH OTHER METALS, AND IN COLORING METALLIC SURFACES
Year: 1841

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
HENRY FOX TALBOT, of Lacock Abbey, in the County of Wilts, Esquire, sond
greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Ier
Letters Patent under the Great Seal of Great Britain, bearing date at
Westminster, the Ninth day of December, in the fifth year of Her reign, did,
for Herself, Iler heirs and successors, givo and grant unto me, the said
William Henry Fox Talbot, IIer especial full power, sole privilege and
authority, that I, the said William Henry Fox Talbot, my cñors, adiiors,
and assigns, or such others as I, the said William Henry Fox Talbot, my
exors, adñiors, or assigns, should at any time agree with, and no others, from
time to time and at all times during the term of years therein expressed,
should and lawfully might make, use, exercise, and vend, within England,
Wales, and the Town of Berwick-upon-Tweed, my Invention of "IMPROVE-
MENTS IN COATING OR COVERING METALS WITH OTHER METALS, AND IN COLORING
METALLIC SURFACES;" in which said Letters Patent is contained a proviso that I,
the said William Henry Fox Talbot, shall cause a particular description of the
nature of my said Inveation, and in what manner the same is to be performed,
to be inrolled in Her said Majesty's IIigh Court of Chancery within six
calendar months next and immediately after the dato of the said in part
recited Letters Patent, as in and by the same, reference being thereunto had,
will more fully and at large appear.
NOW KNOW YE, that in compliance with the said proviso, I the said

page_text: William Henry Fox Talbot, do hereby declare the nature of my sand inven
tion, and the manner in which the same is to be performed, are fully
described and ascertained in and by the following statement thereof (that
is to say):-
The first part of my Invention consists in adding gallic acid to the metallic
solution intended to be precipitated. I take any convenient solution of silver,
gold, or platina, and I add to each of them a solution of gallic acid in water,
ether, or alcohol (which latter I consider preferable). Into any one of these
mixtures I then immerse a clean bright plate of metal until it becomes coated
(as the case may be) with silver, gold, or platina. I find it best in general to
begin with a weak or dilute solution, and afterwards to use a stronger one.
The gallic acid need not be pure, but cheaper liquids containing a considerable
portion of it, or of an analagous vegetable substance, may be used instead of
the pure acid. With respect to this part of my Invention I claim the use of
gallic acid, or liquids containing it, or an analogous vegetable substance, for
facilitating the precipitation of metals upon other metallic surfaces and coating
them therewith.
The next part of my Invention is a method of silvering metallic surfaces.
For this purpose I dissolve freshly precipitated chloride of silver in hypo-
sulphite of soda, or any other liquid hypo-sulphite, which I believe to be the
only class of bodies hitherto discovered which have the property of dissolving
chloride of silver freely and abundantly. Into this solution I then immerse a
clean bright plate of metal, and it is very rapidly coated with a bright silver
coating. In order to obtain thicker coats of metal I employ a galvanic battery
in the way now well known, using one of the liquids described in the first and
second parts of this Specification, and employing for one of the poles or
electrodes a piece of metal of the same kind as that which is intended to be
precipitated. With respect to this part of my Invention I claim the use use
of hypo-sulphite of soda or other liquid hypo-sulphites for the silvering of
metals, and the employing a galvanic battery for obtaining thicker deposits of
silver, gold, or platina; but I claim this only when used in conjunction with
one of the liquids above described. The metals which may be coated with
other metals by the processes above described are brass, copper, silver, German
silver, and also (though less effectually), iron and steel.
The next part of my Invention is a method of ornamenting surfaces of
brass or copper, by first gilding them partially according to some pattern, and
then washing them over with a solution of chloride of platina, which has no
action on the gilt parts, but gives a dead black appearance to the rest of the
surface, thus enhancing the brilliancy of the parts which are gilt.

page_text: The last part of my Invention is a method of coloring polished surfaces of
copper by exposing them to the vapour of sulphuretted hydrogen, or of any of
the liquid hydro-sulphurets, or to the vapours of sulpher, iodine, bromine, or
chlorine, or by dipping the metal into liquids containing them. But I prefer
to use the hydro-sulphurets as above mentioned. By this means very brilliant
colors are obtained on the copper, and, by partially protecting the surface of
the metal according to any determinate or ornamental pattern, very pleasing
effects are produced, exhibiting great contrast of colors in a little space. As
it is easy to render the copper nearly white by the method above described, I
employ it for obtaining metallic specula or mirrors as follows:-I take an
electrotype cast in copper from a polished plane or spherical metallic surface,
which cast has nearly the same degree of polish as the original, and I then
expose it to the action of vapours, as above described, until it is sufficiently
whitened, which is effected without injuring the polish. As the surface of the
speculum thus obtained is already combined chemically with sulphur, or one of
the other bases or substances above mentioned, it is consequently less liable to
tarnish or oxydate subsequently by any exposure to the atmosphere. With
respect to this last part of my Invention I claim the coloring of copper
surfaces by exposing them to the chemical action of the above-named
substances.
In witness whereof, I, the said William Henry Fox Talbot, have here-
unto set my hand and scal, this Eighteenth day of May. in the year