Year: 1895

page_text: Date of Application, 25th Sept., 1895-Accepted, 23rd Nov., 1895
πιρουντ
A communication from abroad by MAX HIRSCH, of Radeberg, Kingdom of
Saxony, German Empire, Glass Manufacturer.
I, GEORGE BELOE ELLIS of the Firm of J. C. Mewburn and Ellis of 55 and
56 Chancery Lane in the County of London, Chartered Patent Agents, do hereby
declare, the nature of this invention and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement:-
For decoloring glass, while in a molteu state, metals or metal compounds have
been used, much as for instance antimony, nickel, zinc, lead, or the oxides of such
metals; furthermore acids have been used, such as arsenious acid; or minerals
such as pyrolusite or manganese; or salts such as saltpetre. But I am not aware
that selenium has ever been made use of for decoloring glass while in a molten
state and it is my invention to use selenium or selenium compound such as a
selenite or a selenate for the above mentioned purpose.
1 am well aware that selenium or selenium compounds have been proposed as
means for coloring glass either rose-red or orange color but not for decoloring
purposes.
My correspondent has found by repeated experiments that by adding a very
small quantity of selenium to the molten glass, glass of a dark shade can be
converted into a white and bright glass of very agreeable appearance; the less the
molten glass is shaded, especially if materials of a better class have been used for
its components or ingredients, the smaller the quantity of selenium may be for
decoloring the same and for obtaining white glass. Again glass molten with potash
will require a smaller addition of selenium than glass molten with soda or Glauber's
salt. My correspondent has found by experiments, that with a quantity of glass,
for which 100 kilogrammes of sand and the necessary quantity of fluor (flux) has
been used, about 1 to 5 grammes of selenium may be used for decoloring the glass.
Experiments have proved, that the same composition of molten glass, for the
decoloring of which nickel has hitherto been used, will deliver a much whiter glass
if selenium be used for decoloring. The selenium may be used as metallic
selenium; or as a selenium compound or composition. It may for example be used
as a selenite or a selenate, that is to say as a selenious acid salt or selenic acid salt,
or it may be used as a selenide (seleniuret of lead) and suitable means of reduction
may simultaneously be used for freeing the selenium from its compounds; or the
selenium may be added to the glass in the form of cullets from glass containing
selenium. The means of reduction are well known; for example if a selenate or a
Belenite be used arsenious acid, arseniate of sodium, or arseniate of potassium may
be employed as the reducing agent.
It may be preferable in some cases to cause a preliminary decoloring of the
molten glass or a simultaneous decoloring of same by adding other decoloring
agents to the molten glass, such for instance as metallic nickel or oxide of nickel,
saltpetre, arsenic and to obtain the higher degree of transparency or whiteness by
adding selenium.

page_text: Having now particularly described and ascertained the nature of the said
invention as communicated to me and in what manner the same is to be performed,
I declare that what I claim is :-
1. The process substantially as hereinbefore described of decoloring molten
glass so as to produce a bright white glass which process consists in adding selenium
in any suitable form to the molten glass and employing when necessary suitable
means of reduction to free the selenium from its compounds or composition.
2. The process substantially as hereinbefore described of decoloring glass which
consists in first effecting a preliminary decoloring of the glass by suitable means,
and then increasing the decoloration or transparency by adding selenium in any
suitable form substantially as set forth.
Dated this 25th day of September 1895.
J. C. MEWBURN & ELLIS,
55 and 56 Chancery Lane, London, Chartered Patent Agents.