IMPROVEMENTS IN SILVERING GLASS
Year: 1855

page_text: LETTERS PATENT to Levi Lewis Hill, of Westhill, in the County of
Greene and State of New York, in the United States of America, for the
Invention of "IMPROVEMENTS IN SILVERING GLASS."
Sealed the 18th November 1855, and dated the 14th May 1855.
PROVISIONAL SPECIFICATION left by the said Levi Lewis Hill at the
Office of the Commissioners of Patents, with his Petition, on the
14th May 1855.
I, LEVI LEWIS HILL, of Westhill, in the County of Greene and State of
New York, in the United States of America, do hereby declare the nature
of the Invention for "IMPROVEMENTS IN SILVERING GLASS" to be as follows:-
The solution or chemical compound is applied to the glass in an india-rubber
pan or other india-rubber implement to suit the size and shape of the glass.
For a flat glass, make a frame of wood; for instance, take some pine strips
from four to six inches wide, and cut them so as to make a frame two
inches larger each way than the glass to be silvered, that is, so large as to
have a two-inch margin all round the glass; then line the frame with india-
rubber cloth, having it smooth on the bottom, and come up the sides to the
top of the pan, tack it all round and fold the corners over, and don't cut them;
then stretch a piece of cotton cloth over the bottom of the pan to support the
rubber, and tack it all round the outside of the pan.
two strips, placed one on each end, that could be
The pan is then to have
directly over the ends of
the glass, in which strips thumb-screws are placed that would descend to the

page_text: corners of the class, and thereby hold the glass firmly to the rubber. The
glass must be thoroughly cleaned before putting it in the pan, and water kept
on it till it is fixed in its place, then pour the water off and pour on the
solution. The rubber pan containing the glass is then placed in a pan of water
heated to 212° Fahrenheit, the pan being kept constantly in a rocking motion
until the glass is silvered, which will be in from 10 to 15 minutes; after it is
done, wash the glass thoroughly in cold water and stand it up to dry. The
glass is then coated with a preparation which preserves the silver, so that it
may be handled without injury. The best coating for this purpose is a solution
composed of gum dammar and sulphuric ether, the consistency of which should
be such as would flow rapidly and evenly over the surface.
To enable others to use this process, I will proceed to state the manner of
making the aforesaid silvering solution.
In the first place, I prepare ammonia nitrate of silver as now used by the
trade, that is to say, I dissolve 1 ounce of pure nitrate of silver in 2 fluid ounces
of water, and mingle with the solution liquid ammonia until the precipitate
first formed is re-dissolved, avoiding an excess of ammonia; I then add a few
grains (say, twenty or thirty) of nitrate of silver, or sufficient to produce a
slight tarry odour. This odour is a suro test of the good condition of the liquid
as adapted to this particular process, and I claim said test as my own Invention.
Ordinary ammonia nitrate of silver is very uncertain in its results unless
brought to said test, but when so brought to said test it works with uniformly
good results. To the above solution I add sixty-two ounces of water, fluid
measure, in which is dissolved 5 grains of mannite, 1 drachm of concentrated
sulphuric ether, and 1 ounce of what I call acidulated sugar, which I prepare
as follows: I dissolve five lb. of best refined sugar in eight pounds of water,
fluid measure, and into this I carefully stir in a small stream one-eleventh its
bulk of chemically pure sulphuric acid; I place the solution in a porcelain
evaporating dish, and apply heat sufficient to raise the temperature to 156°
Fahrenheit in the space of 15 or 20 minutes, stirring constantly with a glass
rod; I then place the solution in a large wooden or earthen vessel, and add to
it successive portions of pulverized chalk until all the acid is neutralized, which
fuscertain by the test of litmus paper; I then strain the liquid through a sack
of cotton flannel, and proceed to evaporate it to a thin syrup, when I filter it
repeatedly through fresh burnt bone black, and then evaporate to a dense
syrup and let it cool.
In this state I consider it about worthless for my
purpose; I therefore modify it by stirring or working it until it becomes very
light colored, when it will work with uniformly good results.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Levi Lewis Hill in the Great Seal Patent Office on the
18th November 1855.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, LEVI
LEWIS HILL, of Westhill, in the County of Greene and State of New York,
in the United States of America, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Fourteenth day of May, in the year of our Lord
One thousand eight hundred and fifty-five, in the eighteenth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
said Levi Lewis Hill, Her special licence that I, the said Levi Lewis Hill, my
executors, administrators, and assigns, or such others as I, the said Levi Lewis
Hill, 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 yend, within the United Kingdom of Great Britain and Ireland, the
Channel Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN
SILVERING GLASS," upon the condition (amongst others) that I, the said Levi
Lewis Hill, by an instrument in writing under my hand and seal, 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 bo
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 Levi Lewis Hill, do hereby declare the
nature of the said Invention, and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement thereof (that is to say):-
The said. Invention for silvering glass with pure silver by the use of
caoutchouc in any and all forms to be as follows:--The solution or chemical
compound is applied to the glass in an india-rubber pan or other india-rubber
implement, to suit the size and shape of the glass. For a flat glass, make a
frame of wood; for instance, take some pine strips, from four to six inches wide,
and cut them so as to make a frame two inches larger each way than the glass
to be silvered, that is, so large as to have a two-inch margin all round the
glass; then line the frame with india-rubber cloth, having it smooth on the
bottom, and come up the sides to the top of the pan, tack it all round and
fold the corners over, and don't cut them; then stretch a piece of cotton cloth
over the bottom of the pan to support the. rubber, and tack it all round the

page_text: outside of the pan. The pan is then to have two strips, placed one on each
end, that would be directly over the ends of the glass, in which strips thumb-
screws are placed that would descend to the corners of the glass, and thereby
hold the glass firmly to the rubber. The glass must be thoroughly cleaned
before putting it in the pan, and water kept on it till it is fixed in its place,
then pour the water off and pour on the solution. The rubber pan containing
the glass is then placed in a pan of water heated to 212° Fahrenheit, the pan
being kept constantly in a rocking motion until the glass is silvered, which will
be in from 10 to 15 minutes; after it is done, wash the glass thoroughly
in cold water and stand it up to dry. The glass is then coated with a pre-
paration which preserves the silver, so that it may be handled without injury.
The best coating for this purpose is a solution composed of gum dammar
and sulphuric ether, the consistency of which should be such as would flow
rapidly and evenly over the surface.
To enable others to use this process, I will proceed to state the manner of
making the aforesaid silvering solution.
In the first place, I prepare ammonia nitrate of silver as now used by the
trade, that is to say, I dissolve 1 ounce of pure nitrate of silver in 2 fluid ounces
of water, and mingle with the solution liquid ammonia until the precipitate
first formed is re-dissolved, avoiding an excess of ammonia; I then add a few
grains, (say, twenty or thirty) of nitrate of silver, or sufficient to produce a
slight tarry odor. This odor is a sure test of the good condition of the liquid
as adapted to this particular process, and I claim said test as my own Inven-
tion. Ordinary ammonia nitrate of silver is very uncertain in its results unless
brought to said test, but when so brought to said test it works with uniformly
good results. To the above solution I add sixty-two ounces of water, fluid
measure, in which is dissolved 5 grains of mannite, 1 drachm of concentrated
sulphuric ether, and one ounce of what I call acidulated sugar, which I prepare
as follows: I dissolve five lb. of best refined sugar in eight pounds of water,
fluid measure, and into this I carefully stir in a small stream one-eleventh its
bulk of chemically pure sulphuric acid; I place the solution in a porcelain
evaporating dish, and apply heat sufficient to raise the temperature to 156°
Fahrenheit in the space of to or 20 minutes, stirring constantly with a glass
rod; I then place the solution in a large wooden or earthen vessel, and add
to it successive portions of pulverized chalk until all the acid is neutralized,
which I ascertain by the test of litmus paper; I then strain the liquid through
a sack of cotton flannel, and proceed to evaporate it to a thin syrup, when I
filter it repeatedly through fresh burnt bone black, and then evaporate to a
dense syrup, and let it cool. In this state I consider it about worthless for my

page_text: purpose; I therefore modify it by stirring or working it until it becomes very
light colored, when it will work with uniformly good results.
What I claim and wish to secure by Royal Letters Patent is, the use of
caoutchouc in the manner described, and the peculiar method herein detailed
of preparing and compounding the aforesaid chemicals. I do not claim the
use of sugar, but of sugar acidulated or modified by acid and the other means,
as described, and the use of mannite and sulphuric ether in the proportions
named.
LEVI LEWIS HILL. (L.S.)
Witness to the signature of Levi Lewis Hill,
above named,
(Consulate
(Coral
GEORGE SCHEDEL,
H. B. M.'s Vice Consul at New York.