AN IMPROVED PROCESS FOR SILVERING. LOOKING GLASS IN PILES OF SEVERAL SHEETS SUPERPOSED WITHOUT INTERRUPTION, WHICH PROCESS CONSISTS IN THE USE OF A CHEMICAL POWDER
Year: 1861

page_text: LETTERS PATENT to Charles Husson, of Nantes, in the Empire of
France, Looking Glass Manufacturer, for the Invention of "AN
IMPROVED PROCESS FOR SILVERING. LOOKING GLASS IN PILES OF SEVERAL
SHEETS SUPERPOSED WITHOUT INTERRUPTION, WHICH PROCESS CONSISTS IN THE
USE OF A CHEMICAL POWDER."
Sealed the 28th March 1862, and dated the 4th October 1861.
PROVISIONAL SPECIFICATION left by the said Charles Husson at the
Office of the Commissioners of Patents, with his Petition, on the 4th
October 1861.
I, CHARLES HUSSON, of Nantes, in the Empire of France, Looking Glass
Manufacturer, do hereby declare the nature of the said Invention for "AN
IMPROVED PROCESS FOR SILVERING LOOKING GLASS IN PILES OF SEVERAL SHEETS
SUPERPOSED WITHOUT INTERUPTION, WHICH PROCESS CONSISTS IN THE USE OF A
CHEMICAL POWDER," to be as follows:-
In demonstrating my Invention, I assume the silvering table to be six feet
six inches in length, by four feet ten inches in width, including the mercurial
conduits or gutters (it may be of any dimensions). 1°. I silver by the known
processes a glass six feet in length, by four feet six inches in width, which
nearly covers the surface of the table. 2°. Upon the upper face of this first
silvered plate, I spread a fine powder which has no action on the surfaces it
touches but is intended solely to prevent adhesion. This powder is composed

page_text: of silicate of magnesia, starch made from wheat, and white soap, pulverized
and passed through a fine sieve; a fine powder is thus produced, which must
be dried to free it from all humidity. I spread the sheet of tin foil on the surface
thus powdered. I apply the mercury in the usual manner and quantity, and silver
the second plate, sliding it on the first. I proceed in the same manner with
powder, tin foil, and mercury, and slide on at hird, fourth, fifth, or more plates,
(each one decreasing in size,) until no more can be piled.
3°. My process
does not limit the number of piles, they may be silvered by two, three, or four,
according to the surface of the table and the superficial volume of the glass;
I subdivide several piles above these plates if desired.
4°. I effect my
silvering without removals or. being arrested by the greater or lesser thickness
of the plates. From long practice I require no other guide or rest than the
edge of the last silvered plate; others may desire to use a moveable guide,
mine consists of a rule rising to the same level as each plate piled and which
levels at the edge of the table. To give this a graduated movement, I prefer
to use two racks placed beneath its extremities motived by two toothed wheels
moving on one shaft to which an easy and precise motion may be given. 5°.
The operation thus terminated, I-slightly incline the table as is usually done to
facilitate the flow of the superabundant mercury. As by my method this
flow takes place more promptly, I lift the plates much sooner, and place them
on the drainer.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Charles Husson in the Great Seal Patent Office on the 2nd
April 1862.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, CHARLES
HUSSON, of Nantes, in the Empire of France, Looking Glass Manufacturer,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Fourth day of October, in the year of our Lord
One thousand eight hundred and sixty-one, in the twenty-sixth year of a
Her reign, did, for Herself, Her heirs and successors, give and grant unto
me, the said Charles Husson, Her special licence that I, the said Charles
Husson, my executors, administrators, and assigns, or such others as I,
the said Charles Husson, 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

page_text: 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
"AN IMPROVED PROCESS FOR SILVERING LOOKING GLASS IN PILES OF SEVERAL SHEETS
SUPERPOSED WITHOUT INTERRUPTION, WHICH PROCESS CONSISTS IN THE USE OF A
CHEMICAL POWDER," upon the condition (amongst others) that I, the said
Charles Husson, 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 Charles Husson, 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, reference being had to the Sheet of Drawings hereunto
annexed, and to the figures and letters of reference marked thereon :-
By my Invention many sheets of glass, either diminishing in size or all of
equal size, may be silvered on the same table, the one being piled upon the
other as the silvering progresses, and thus I silver five or six times more
surface than can be done by any process now in use in the same time and with
the same space or room at command.
I will first describe my process of silvering sheets of glass in piles, such
sheets diminishing in size, as shewn at Figure A in the Drawing. I take a
silvering table regardless of its dimensions, construction, or auxiliary parts.
For purposes of demonstration, I will presume it to be six feet six inches long
by four feet ten inches broad, inclusive of the mercurial conduits. Firstly, on
this table I silver by the usual process a glass six feet long by four feet six
inches broad, the which covers the surface of the table, and produces a
superficie of twenty-seven feet. Secondly, on the top of this first silvered plate
I spread a fine powder (the composition of which is herein-after described)
which does not act upon the surfaces which it touches, but simply prevents
their adhesion. I spread the sheet of foil on the surface thus powdered;
I prepare it with mercury as in the ordinary process, and in the same pro-
portion; then, with or without rest other than the edge of the first silvered
glass, I silver the second, sliding it on to the first (this second glass being six
feet two inches in length (or more) and four feet four inches (or more) in
breadth), and having operated thereupon with powder foil and mercury, I slide
on the third, and continue silvering and piling in the same manner a fourth,
fifth, and sixth, or as many as the gradually diminishing surface of the pile

page_text: will permit (see Figure A, which is drawn to one twenty-fifth of the natural
size).
Thirdly, my process does not limit the number of piles, as two, three, four,
or more may be silvered on the same table according to its surface, and the
superficial volume of the plates of glass, and on large glasses I may further
subdivide the piles.
Fourthly, I always effect my silvering without shifting and without regard
to the greater or lesser thickness of the plate. Although practice will enable
a good silverer to dispense with other guide or leverage than the edge of the
last silvered glass, to complete my process and render it generally available,
I have provided a moveable guide, consisting of a rule grazing the side of the
table, and rising to the level of each piled glass. Amongst the many means
which may be used to give to this guide or rule a graduated motion, that which
I prefer consists in the use of two racks placed under its extremities, moved
by two toothed wheels turning on one shaft, to which the operation may com-
municate an easy-and precise motion.
Fifthly, the operation thus terminated, I slightly incline the table, as is
usual, to facilitate the escape of the superabundance of mercury; but as this
retreat or escape is by my process already rendered more prompt, I can lift
the plates much quicker and place them to drain. Silvering in piles gives
more perfect finish than the usual process. If I desire to silver without
interruption sixty or eighty plates (say of thirty-nine inches by twenty-six
inches, I must cut the sheets of foil exactly to the glass. (I am now
describing my process of silvering plates of equal size, superposing them in
piles.) I take the wooden board shewn at Figure E and at No. 1, Figure F,
which is six inches high, and pierced at bottom with small holes to drain the
mercury, has a return angle at one end, and a cross piece at the other to keep
it straight. This board supports a moveable T, of wood or iron, which is
raised or lowered at will, and is placed on one side of the table, leaving in
front a distance the breadth of the plates to be silvered.
I apply the first
sheet of foil, and after preparing it with mercury, I bring the wooden board to
the edge of the foil. I pour the mercury less thickly than in the ordinary
process, and then, instead of using a strip or band of paper as in such process,
I take a large sheet of plain glazed paper. A wooden roller applied to the
moveable horizontal ruler, and upheld by two iron hooks or catches, will open
to pinch the sheet of paper and wind it (see Figure H, and No. 2, Figure F).
I push with a bare's foot (in the usual manner) the dross or scum of the
mercury in a breadth of two inches to the side which touches the board No., 1.
I-advance-the-sheet-of-paper-by-unrolling-it, and-apply-it-to-cover-the-entire-

page_text: surface of the mercury. I take the plate of glass and lay it flat upon the
paper, then lower the wooden T, which will press upon the other edge of the
glass. This sliding T is stopped by a turn of the screw from above; I then
turn the wooden roller, which gradually enrolls and withdraws the, paper,
moving it more slowly towards the end: in order that air, may not penetrate
between the mercury and the glass. The paper in retiring will have withdrawn
all the mercurial dross or scum, and the glass will be well silvered (see No. 2,
Figure J.in the Drawing). I then raise the T, and advance the horizontal.
ruler to the level of the silvered glass, the roll of paper following the same
graduated movement. I immediately spread the chemical powder over the
glass, apply a second sheet of foil, prepare and lay on the mercury, push back
the scum from the other edge, unroll the paper, and continue the operation
until ten, fifteen, twenty, or more plates are silvered. The paper may be
larger than the plate, so it is not necessary to change it for every size of plate.
On the top of the pile I place a few weights (around the edges) and continue
another pile by the side of the first; I then pass with the mechanism to the
other side of the table, and silver two other piles, the whole without other care
than to wipe the paper from time to time with a warm linen rag. In silvering
plates of equal dimensions, I produce on an equal space at least fifty times
more than by the usual process, that is to say, that instead of silvering four
plates without interruption, I silver sixty or eighty. But although by my
process there is more promptitude in the operation, nevertheless it must
naturally require more time to silver sixty or eighty plates than for a single
plate. Each pile may also, if necessary, be formed of plates of different sizes
(see No. 3, Figure F). Silvering by the aid of paper applied as above
described may also be applied to piles of glass, gradually decreasing in size, as
at Figure A, but to silver very large and heavy plates a very strong and even
paper will be required, which the pressure of the glass will not cause to leave
any loose fibre, that is to say, paper specially made and prepared for this
purpose. This process of silvering is less fatiguing to the workman, and the
skill is quite mechanical instead of depending on the precision of the hand.
My process of silvering plates of glass in piles consists in a great measure in
the use of the chemical powder, without which they could not be separated,
but its combination with the mechanical means completes my Invention.
This chemical powder is composed of three matters in the following pro-
portions: White soap in powder about nine ounces; silicate of maganesia
about twelve and a half ounces; starch (the residue of wheat) about fourteen
ounces; the whole well pulverized, sifted, and quite dry. Plates silvered as
above may be lifted three, four, or five hours after the operation (according to

page_text: the dryness or humidity of the atmosphere) to be placed to drain. One man
will press a flat wooden rule against the narrowest edge of each glass, and
while he presses another workman will lift the other end with a knife or sharp
edged piece of iron, and slide one or more wooden wedges, tapering according
to the size of the plate to be lifted; he will then take it with both hands by
nipping or pressing against each side and raise the end one to two inches; the
other person then abandons the rule at his edge, and nips the plate with both
hands, extending his arms, and they carry it thus to an adjoining table covered
with cloth or flannel, on which they turn it the silvered side uppermost.
When lifting plates of equal dimensions, the rule will be used upright instead
of flat, so that it attains the height of the pile, or any piece of wood sufficiently
high may be used. As to small plates which may be lifted by one person,
they may be easily removed by pinching or pressing the fingers against each
side. It is not necessary to wipe off the powder which remains on the silvered
surfaces, it being more useful than injurious; as to that which remains on the
reflecting surface, it is removed when required with water and a rag. This
powder cleans and smooths the glass, and may be used to take off any
greasiness from the plates before silvering, in giving the last rub with the
duster or rag to the surface which is to receive the mercury..
In witness whereof, I, the said Charles Husson, have hereunto set my
hand and seal, this Twenty-ninth day of March, in the year of our
Lord One thousand eight hundred and sixty-two.
CHARLES HUSSON. (L.S.)