IMPROVEMENTS IN THE MANUFACTURE OF LOOKING GLASSES, MIRRORS, AND OTHER REFLECTING SURFACES
Year: 1864

page_text: LETTERS PATENT to John Henry Johnson, of 47, Lincoln's Inn Fields, in
the County of Middlesex, Gentleman, for the Invention of "IMPROVEMENTS
IN THE MANUFACTURE OF LOOKING GLASSES, MIRRORS, AND OTHER REFLECTING
SURFACES." A communication from abroad by Edouard Dodé, of Paris,
in the Empire of France.
Sealed the 6th December 1864, and dated the 18th June 1864.
PROVISIONAL SPECIFICATION left by the said John Henry Johnson
at the Office of the Commissioners of Patents, with his Petition,
on the 18th June 1864.
I, JOHN HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County of
Middlesex, Gentlemen, do hereby declare the nature of the said Invention for
"IMPROVEMENTS IN THE MANUFACTURE OF LOOKING GLASSES, MIRRORS, AND OTHER
REFLECTING SURFACES," a communication to me from abroad by Edouard Dodé,
of Paris, in the Empire of France," to be as follows:-
This Invention consists in the employment of platinum in the manufacture
of looking glasses and other reflecting substances as a substitute for silver or
for the tin amalgam hitherto employed in such manufacture.
In carrying out this Invention 100 parts by weight of platinum are
dissolved in aqua regia, or nitrochlorohydric acid, or nitro muriatic acid, and
evaporated to dryness. The product thus obtained is then mixed with
essence of lavender or other suitable essential oil; 25 parts by weight of
litharge or any other suitable preparation of lead are to be well ground with

page_text: essence of lavender or other suitable essence on a glass pallet. Having
prepared the above two products separately, they are to be intimately mixed
together, and after being diluted with a little essence of lavender, the substance
is ready to be applied to the surface of the glass, which may be accomplished
with a brush or otherwise. The glass thus coated is then to be subjected to
an elevated temperature in a muffle, and when removed therefrom it will be
found to be brilliant and ready for the market.
Mirrors or reflecting surfaces may be made in various ways according to
the glass employed; thus when using crystal or pure white glass without
defects, the prepared platinum may be applied to the back of the glass only.
When employing impure crystal containing defects or flaws, or having a high
color like bottle glass, for example, it is preferred to apply the preparation on
the front surface of the glass only; and, finally, if a good mirror or reflecting
surface is required to be produced from slightly colored glass, the preparation
should be applied to both surfaces.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said John Henry Johnson in the Great Seal Patent Office on
the 14th December 1864.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County of Middlesex,
Gentleman, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Eighteenth day of June, in the year of our Lord One
thousand eight hundred and sixty-four, in the twenty-seventh year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me,
the said John Henry Johnson, Her special license that I, the said
John Henry Johnson, my executors, administrators, and assigns, or such
others as I, the said John Henry Johnson, my executors, administrators, or
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 MANUFACTURE OF LOOKING GLASSES,,
MIRRORS, AND OTHER REFLECTING SURFACES," a communication to me from
abroad by Edouard, Dodé, of Paris, in the Empire of France, upon the con-
dition (amongst others) that I, the said John Henry Johnson, my executors

page_text: or administrators, by an instrument in writing under my hand and seal, or
under the hand and seal of one of them 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 John Henry Johnson, 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 said Invention consists in the employment of platinum in the manu-
facture of looking glasses, mirrors, and other reflecting surfaces as a substitute
for silver or for the tin amalgam hitherto employed in such manufacture.
In carrying out this Invention one hundred parts by weight of platinum are
dissolved in aqua regia or nitrochlorohydric acid, or nitro muriatic acid and
evaporated to dryness. The product thus obtained is then mixed with essence of
lavender or other suitable essential oil; twenty-five parts by weight of litharge
or any other suitable preparation of lead are to be well ground with essence of
lavender or other suitable essence on a glass pallet. Having prepared the
above two products separately, they are to be intimately mixed together, and
after being diluted with a little essence of lavender, the substance is ready to
be applied to the surface of the glass, which may be accomplished with a
brush or otherwise; the glass thus coated is then to be subjected to an
elevated temperature in a muffle, and when removed therefrom it will be
found to be brilliant and ready for the market. The glass should be main-
tained at a cherry-red heat during a period of from four to eight hours, but
the time and temperature will vary according to the greater or less fusibility
of the glass under treatment.
Mirrors or reflecting surfaces may be made in various ways according to
the glass employed; thus when using crystal or pure white glass without
defects, the prepared platinum may be applied to the back of the glass only.
When employing impure crystal containing defects or flaws, or having a high
color like bottle glass, for example, it is preferred to apply the preparation on
the front surface of the glass only; and, finally, if a good mirror or reflecting
surface is required to be produced from slightly colored glass, the preparation
should be applied to both surfaces.
Looking glasses and mirrors manufactured according to this Invention not
only present a most brilliant appearance, but are cheaper than those made
according to the ordinary mode of manufacture.

page_text: I am aware that platinum has been applied in a solid form to the surface
of articles of porcelain, pottery, and crockery ware, and therefore I lay no
claim to its application to such substances; but what I consider as novel and
original, and therefore claim as the Invention secured to me by the herein-
before in part recited Letters Patent, is,―
First, the mode of treatment, herein-before described, for rendering platinum
applicable to the surface of glass for the manufacture of looking glasses and
mirrors.
Second, the application of platinum to the surface of glass or crystal for
the obtainment of looking-glasses and mirrors, substantially as herein-before
described.
Third, the use of looking-glasses and mirrors obtained by the application of
platinum to one or both surfaces of the glass, as herein-before described.
Fourth, the general system or mode of making looking-glasses and mirrors
wherein platinum is substituted for the ordinary tin foil or silver, substantially
as herein-before described.
In witness whereof, I, the said John Henry Johnson, have. hereunto
set my hand and seal, the Fourteenth day of December, One thousand
eight hundred and sixty-four.
J. HENRY JOHNSON.
(L.S.)