MENTS IN THE MANUFACTURE OR TREATMENT OF GLASS AND CRYSTAL."
Year: 1878

page_text: :
PROVISIONAL SPECIFICATION left by Benjamin Joseph Barnard Mills at
the Office of the Commissioners of Patents on the 14th January 1878. A
communication from abroad by Antoine Mayet-Paturle, of Lyons, in the
Republic of France.
"
BENJAMIN JOSEPH BARNARD MILLS, of the Firm of Harris and Mills, of 23,
Southampton Buildings, in the County of Middlesex, Patent Agent. IMPROVE-
MENTS IN THE MANUFACTURE OR TREATMENT OF GLASS AND CRYSTAL."
A com-
munication from abroad by Antoine Mayet-Paturle, of Lyons, in the Republic
of France."
L
The Invention has for its object improvements in the manufacture or treat-
ment of glass and crystal by the employment of a chemical process which gives
to all descriptions of glass and crystal fixity and constancy of composition, and
thereby renders them insensible to thermometric variations.
The Invention has for its object to remedy certain imperfections which all the
manufactured silicates present in their numerous applications. Of whatever base,
whether of lime, potash, or other or even metallic, all the silicates in one word are
liable to the imperfections which their transformation into commercial objects in-
variably produces.
All manufactured articles, whether of glass or crystal, are more or less defective
with respect to the fixity of the molecules composing them, and lose consequently
constancy of composition, whether this defect proceeds,―
First, from the defective composition of the vitrefiable materials; or second, from
their imperfect fusion; or third, from the workman who made them by the aid of
excessively hot or cold tools too much or too little moistened or greased, or who has
made them under the influence of a current of air; or fourth, from the badly con-
ducted cooling of the manufactured articles.
Further, there results from the first and second cases a non-homogeneous mass, and
from the third and fourth a partial or total shrinkage. When a vitreous mass is
not homogeneous, that is to say, that it is constituted by the combination of silicates
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of different nature and density, the expansion and contraction of these silicates are
unequal, which causes the want of fixity of molecules which compose their mass.
When a manufactured article has suffered under the influence of cold a shrinkage
of even the smallest kind, whether in its entirety or in one or more of its parts, the
surfaces cooled or shrunk are powerfully contracted and hardened; they preserve
the volume which they had acquired under the influence of heat, and the internal
molecules are distended beyond measure for fixing them.
It is easy to understand that this condition is abnormal and defective, which is
explained and proved sufficiently by studying the fragments of these glasses when
once they are broken. As a conclusion of these latter paragraphs, one must not be
surprised to see that capricious fracture, those sudden explosions which occur, and
most frequently without any apparent cause......
To remedy these grave inconveniences the manufacturer refires or anneals the
manufactured articles; but like all other manufacturers, the Inventor has discovered
that not one of the numerous processes hitherto in use gave the fixity and the con-
stancy of composition which they may acquire.
The Inventor has discovered that to restore to glass and crystal these valuable
qualities, it was indispensable to substitute for the refiring or annealing operation,
another operation which modified their chemical composition, once made, without in
any way altering their transparency, their form; and their beauty; and the following
is the mode of operation:-Substances employed to modify the chemical composition
of silicates in general to the effect above described. The substances retained specially
for effecting this operation, which is the object of the present Invention, are all
substances in the chemical composition of which carbon enters in notable quantity; or
more explicitly, all known substances in nature, whether solid, liquid, simple,
mixed or compound, melted or dissolved, or even in the state of gas, which
contain a notable quantity of carbon, carbonaceous substances not being capable
of acting chemically upon the silicates at the temperature of the surrounding
air, this operation is conducted by the aid of heat.
Silicates submitted to the influence of carbon lose their primitive chemical com-
position, and this new state modified sensibly the mode of combining the molecules
which compose their mass. It is from this general transformation that the
advantages possessed by glass, crystal, or silicates thus treated are derived.
Mode of Operation. There is placed in a suitable receiver or in a metallic boiler,
the objects upon which it is desired to operate. The said boiler or receiver is filled
with one of the substances above designated, and it is so arranged that the objects
are a little separated from each other, and in contact only with the substance having
a carbon base, then the boiler or vessel is closed by means of a well-fitting cover.
The articles and the reactionary substance being at the temperature of the sur-
rounding air, they may be considered as cold; and if it is possible to operate at a
much greater degree of cold, it should be done by preference.
The whole is gradually heated as slowly as possible until it has attained a degree
of temperature sufficiently high to render possible the chemical action of the
carbonaceous material upon the silicates. This temperature is maintained a certain
time, then it is left to cool.
It should be mentioned here that contrary to what has hitherto been done,
namely, utilising heat to produce upon articles of glass and crystal a physical effect
called annealing glass, the heat is only employed as an auxiliary to set up the
chemical action of the carbonaceous matter. This operation should not be carried
too far, as it would promote the decomposition of the reactionary substance, the
chemical effect would be no longer produced, and the operation would not procure
the desired result.
General Rules and Observations.-It should here be observed,―
First. The nearer the point of commencement as regards degree of cold of the car-
bonaceous substance, and the objects approach to zero centigrade, to rise slowly to
the highest degree of temperature that it is desired to attain, the less risk there is of
breaking the articles.

page_text: Second. The longer the duration of the high temperature is prolonged, the greater
is the chemical action. This time can be fixed at an hour for the minimum for small
objects, but it is indispensable to increase this time in proportion to the thickness
of the objects.
Third. The more slowly and regularly the heat is allowed to pass off, the more pro-
longed is the chemical action. The silicates then take a greater fixity and constancy
in their composition.
Fourth. It is indispensable to leave the articles to cool with and in the substance
employed; as soon as all is completely cold, the articles are withdrawn to cleanse
and use them.
Fifth. To obtain a better result the operation may be renewed several times.
Gaseous Substances.-If the reactionary substance is in a gaseous form, the glass
may be placed in a muffle furnace or in refractory crucibles of earth or of metal her-
metically closed, into which the carbonaceous gases are introduced. In this case
the furnaces or crucibles should be submitted to the same degrees of temperature
as above mentioned, nevertheless the duration of the high temperature which is the
time in which the chemical action takes place should be sensibly increased. The
entire should also be allowed to heat and cool under the same conditions as those
above mentioned.
The right is further reserved to enclose the articles, as also the carbonaceous sub-
stance in a boiler which can be hermetically closed. (This boiler should be furnished
with the necessary safety apparatus) in order to effect the chemical action under the
influence of a pressure obtained either by the disengagement of the vapors or of the
gases of the substances employed, or by any other means which may be judged
convenient.
Advantages of Glass and Crystal thus Treated.-The process thus described is
applicable to all glasses and crystals, whatever may be their form, their composition,
their thickness, and their uses, in whatever manner they may have been treated
during and even after their manufacture, whether they are plated, painted, gilt,
silvered or otherwise. The action of this process is precise and uniform upon all
articles. It is permanent and cannot be ineffective except in the case of the articles
prepared being made red and deformed.
Glasses and crystals thus treated gain much in transparency, in brilliancy, and
beauty. They endure successfully rapid changes of temperature which quality gives
them the first rank among all descriptions of glass and crystal made or prepared by
any other system to resist the action of heat. When they break they do so without
explosion, and their fragments are identical to those of ordinary glass in form,
dimension, and cutting. They may be cut by the diamond, and cut or engraved by
the wheel or by acid without losing their new property.