DOI Page / Citation link:
https://doi.org/10.11588/diglit.1398#0080
PLATE 125.
AUSTRIAN ORNAMENTAL GLASS,
BY COUNT HAERACH AND ME. W. HOFFMAN.
/"^ OTJJSTT HARBAOH, of Neuwelt, in Bohemia, who occupied so distinguished a position
^-/ at the Exhibition of 1851 as an enterprising and intelligent manufacturer of ornamental
glass, obtained a prize medal at the present Exhibition " for excellence of manufacture of flint
glass and ornamental articles." We have already noticed the works of Mr. Hoffman in the
letter-press appended to Plate 33. The height of the large white vase, gilt and jewelled, by
Count Harrach, was about 5 feet 6 inches; it consisted naturally of several pieces, and presented a
remarkably rich and agreeable appearance.
Bohemia has for a long period been celebrated for its coloured glass. Kunkel, whom we have
already spoken of in connection with the fine ruby glass of Bohemia (see Plate 5), states that the
colouring power of the purple precipitate of Cassius is so great, that one part added to a thousand
parts of glass will impart to the whole a full rich body of colour. This artist was ennobled by
Charles XL of Sweden for his improvements in the art of colouring glass, and assumed the name
of Lowenstiern. He states, in his " Ars Vetraria," that he made artificial rubies in great abundance
and sold them at a high price. Eor the Elector of Cologne he made a cup of ruby glass, fully
an inch in thickness, weighing twenty-four pounds, and of an equally beautiful colour throughout.
He was principally employed in this art when he was engaged in the service of Frederick William,
the Elector of Brandenburg, in the year 1679, by whom he was made inspector of the glass-houses
at Potsdam. Kunkel has nowhere given a complete account of the method he practised, and states
also that he could produce ruby glass without gold. John C. Orschal, who was in the service
of the Elector of Saxony about the year 1682; Christopher Grummet, an assistant of Kunkel's,
and Kriiger, inspector of glass-houses to the first king of Prussia, also distinguished themselves
by their productions in coloured glass, and especially ruby. Dr. Euss was the first to prove
that a common solution of gold, without the presence of tin, which is a constituent part of the
precipitate of Cassius, is capable of producing rose and carmine-coloured glass. In lire's "Dictionary
of Arts and Manufactures," it is stated that "perhaps the glass is colourless in the pot, and it
then remains colourless when cold; but when re-heated, the glass quickly assumes a light red colour,
which rapidly spreads from the heated point over the whole piece, and increases in intensity until
it becomes nearly a black red. This coloured glass can be again rendered colourless by fusion and
slow cooling, and its colour be again produced by a repetition of the heating process. If, however,
it is suddenly cooled, it cannot again be made to resume its ruby colour. This is also an example
confirmatory in the highest degree of the view that no chemical change takes place, but that all
the phenomena are due to alterations in molecular structure." M. Bontemps, who has made
various important experiments at his glassworks at Ohoisy-le-Roi, found that gold, although usually
employed for the purpose of giving various tones of red to glass, would by varying degrees of heat
at a high temperature, and re-casting several times, produce a great many tints, varying from blue
to pink, red, opaque, yellow, and green. Moreover, he found that all the colours of the prismatic
spectrum might be given to glass by using the oxide of iron in various proportions, and by the
agency of different degrees of heat; from which he concludes that all the colours are produced in
their regular disposition in proportion as the temperature is increased. A series of similar changes
was found under the same circumstances to take place with the oxide of manganese, which is
generally employed to give a pink or purple colour to glass, and with the oxides of copper, used
generally in producing red glass. Silver also, which imparts a beautiful yellow colour to glass,
underwent the same changes, though with less intensity; and M. Bontemps is disposed to refer
these chromatic changes to some modification of the composing particles rather than to any chemical
changes in the materials employed. Besides the colours already mentioned, charcoal and antimony
produce yellow glass, uranium a fine canary-yellow. Opaque white glass is made with the oxide
of tin or phosphate of lime; the beautiful opal glass with muriate of silver, magnetic iron ore,
and bone ash in certain proportions; blue glass with cobalt; and other colours are produced by
various metallic and mineral products. Imitation gems, or " pierres de Strass," which are brought
to great perfection in various countries (in Austria principally at Gablontz), receive their finish
from the hands of the glass-cutters and grinders.
AUSTRIAN ORNAMENTAL GLASS,
BY COUNT HAERACH AND ME. W. HOFFMAN.
/"^ OTJJSTT HARBAOH, of Neuwelt, in Bohemia, who occupied so distinguished a position
^-/ at the Exhibition of 1851 as an enterprising and intelligent manufacturer of ornamental
glass, obtained a prize medal at the present Exhibition " for excellence of manufacture of flint
glass and ornamental articles." We have already noticed the works of Mr. Hoffman in the
letter-press appended to Plate 33. The height of the large white vase, gilt and jewelled, by
Count Harrach, was about 5 feet 6 inches; it consisted naturally of several pieces, and presented a
remarkably rich and agreeable appearance.
Bohemia has for a long period been celebrated for its coloured glass. Kunkel, whom we have
already spoken of in connection with the fine ruby glass of Bohemia (see Plate 5), states that the
colouring power of the purple precipitate of Cassius is so great, that one part added to a thousand
parts of glass will impart to the whole a full rich body of colour. This artist was ennobled by
Charles XL of Sweden for his improvements in the art of colouring glass, and assumed the name
of Lowenstiern. He states, in his " Ars Vetraria," that he made artificial rubies in great abundance
and sold them at a high price. Eor the Elector of Cologne he made a cup of ruby glass, fully
an inch in thickness, weighing twenty-four pounds, and of an equally beautiful colour throughout.
He was principally employed in this art when he was engaged in the service of Frederick William,
the Elector of Brandenburg, in the year 1679, by whom he was made inspector of the glass-houses
at Potsdam. Kunkel has nowhere given a complete account of the method he practised, and states
also that he could produce ruby glass without gold. John C. Orschal, who was in the service
of the Elector of Saxony about the year 1682; Christopher Grummet, an assistant of Kunkel's,
and Kriiger, inspector of glass-houses to the first king of Prussia, also distinguished themselves
by their productions in coloured glass, and especially ruby. Dr. Euss was the first to prove
that a common solution of gold, without the presence of tin, which is a constituent part of the
precipitate of Cassius, is capable of producing rose and carmine-coloured glass. In lire's "Dictionary
of Arts and Manufactures," it is stated that "perhaps the glass is colourless in the pot, and it
then remains colourless when cold; but when re-heated, the glass quickly assumes a light red colour,
which rapidly spreads from the heated point over the whole piece, and increases in intensity until
it becomes nearly a black red. This coloured glass can be again rendered colourless by fusion and
slow cooling, and its colour be again produced by a repetition of the heating process. If, however,
it is suddenly cooled, it cannot again be made to resume its ruby colour. This is also an example
confirmatory in the highest degree of the view that no chemical change takes place, but that all
the phenomena are due to alterations in molecular structure." M. Bontemps, who has made
various important experiments at his glassworks at Ohoisy-le-Roi, found that gold, although usually
employed for the purpose of giving various tones of red to glass, would by varying degrees of heat
at a high temperature, and re-casting several times, produce a great many tints, varying from blue
to pink, red, opaque, yellow, and green. Moreover, he found that all the colours of the prismatic
spectrum might be given to glass by using the oxide of iron in various proportions, and by the
agency of different degrees of heat; from which he concludes that all the colours are produced in
their regular disposition in proportion as the temperature is increased. A series of similar changes
was found under the same circumstances to take place with the oxide of manganese, which is
generally employed to give a pink or purple colour to glass, and with the oxides of copper, used
generally in producing red glass. Silver also, which imparts a beautiful yellow colour to glass,
underwent the same changes, though with less intensity; and M. Bontemps is disposed to refer
these chromatic changes to some modification of the composing particles rather than to any chemical
changes in the materials employed. Besides the colours already mentioned, charcoal and antimony
produce yellow glass, uranium a fine canary-yellow. Opaque white glass is made with the oxide
of tin or phosphate of lime; the beautiful opal glass with muriate of silver, magnetic iron ore,
and bone ash in certain proportions; blue glass with cobalt; and other colours are produced by
various metallic and mineral products. Imitation gems, or " pierres de Strass," which are brought
to great perfection in various countries (in Austria principally at Gablontz), receive their finish
from the hands of the glass-cutters and grinders.