Transcriber's Notes
When italics were used in the original book, the corresponding text
has been surrounded by _underscores_, and when boldface text was use,
the corresponding text has been surrounded by =equal signs=. In two
instances, the letter N has been printed with a macron above it. This
has been represented as [=N]. Superscripted letters have been preceded
by ^ and when multiple letters are superscripted they have been
surrounded by {}. Subscripted letters and numbers have been preceded
by _ and surrounded by {}. Fractions have been separated from whole
numbers preceding them with a dash such that 1-1/2 represents one and
one half. The letters represented as H./W.E. were originally printed
with the H. directly above the other two letters.
Some presumed printer's errors have been corrected. These are listed in
a second transcriber's note at the end of the text.
THE CONNOISSEUR’S LIBRARY
GENERAL EDITOR: CYRIL DAVENPORT
GLASS
------------------------------------------------------------------------
[Illustration:
_PLATE I_
ENAMELLED GOBLET
VENETIAN OR FRANCO-SYRIAN. CIRCA 1300, A.D.]
------------------------------------------------------------------------
GLASS
BY
EDWARD DILLON, M.A.
[Illustration: The Connoisseur’s Library]
NEW YORK: G. P. PUTNAM’S SONS
LONDON: METHUEN AND CO.
1907
------------------------------------------------------------------------
PREFACE
It is now nearly thirty years since the late Mr. Nesbitt wrote the
introduction to the catalogue of the glass at South Kensington. Some
years previously the description of the glass in the Slade collection
had been intrusted to the same gentleman. Since that time many works
treating of special departments of the history of glass have been
published in France, in Germany, and in Italy. Much fresh light has
been thrown upon the primitive glass of the Egyptians; our knowledge of
the glass of both the Near and the Far East has been revolutionised;
abundant fresh material has been provided for the history of Byzantine
glass, and the wanderings of the glass-workers from L’Altare and Murano
have been traced in full detail. Mr. Hartshorne, in his _Old English
Glasses_, has exhaustively told the story of our native glass from the
documentary side, and has described with the minutest detail the
wine-glasses of the eighteenth century. Apart, however, from the
introductory chapters of the last work, I know of no attempt of recent
years to give a general account of the history of glass—using that
term in the narrower sense—as viewed from the artistic side.
We have at hand in the British Museum a collection of glass that has no
rival elsewhere; only second to it is the collection at South
Kensington. It is in these collections that the history of glass must
be studied. I have from time to time in the following pages called
attention to the most remarkable examples. I hope that what I have said
may assist the student in threading his way through what is a rather
complicated history.
My best thanks are due to Mr. C. H. Read, who has charge of the glass
in the British Museum, for the facilities that he has afforded me in
the photographing of the examples in his department; not less to Mr. A.
B. Skinner, director of the Victoria and Albert Museum, for similar
facilities at South Kensington.
I am indebted to Professor Church for much valuable information and for
some hitherto unpublished analyses of glass; to Lord Rothschild and to
Mr. Vincent Robinson, C.I.E., for photographs of examples of glass in
their collections; finally, to Signor Ongania, of Venice, for
permission to reproduce from Passini’s great work on the Treasury of
St. Mark’s some photographs of the glass there preserved.
E. D.
CONTENTS
PAGE
PREFACE, v
LIST OF ILLUSTRATIONS, ix
SELECTED BIBLIOGRAPHY OF WORKS ON GLASS, xxii
KEY TO THE BIBLIOGRAPHICAL LIST, xxviii
CHAPTER I. Introduction, 1
CHAPTER II. Primitive Glass of the Egyptians and Syrians, 18
CHAPTER III. Later Greek Glass and the Moulded and Cast Glass of
the Roman Empire, 43
CHAPTER IV. The Blown Glass of the Roman Empire, 59
CHAPTER V. Early Christian Glass, Byzantine Glass, and the Glass of
the Middle Ages in the East and the West, 89
CHAPTER VI. Glass from Anglo-Saxon and Frankish Tombs. The
so-called Hedwig Glasses, 107
CHAPTER VII. Mediæval Treatises on Glass, 118
CHAPTER VIII. Glass of the Later Middle Ages in Western Europe, 132
CHAPTER IX. The Enamelled Glass of the Saracens, 144
CHAPTER X. The Enamelled Glass of the Saracens (_continued_), 161
CHAPTER XI. The Glass of Venice—The Origins—Beads, 174
CHAPTER XII. The Enamelled Venetian Glass of the Fifteenth Century, 192
CHAPTER XIII. Varieties of Venetian Glass—Early Literature, 200
CHAPTER XIV. The French Glass of the Renaissance, 220
CHAPTER XV. The Renaissance Glass of the Spanish Netherlands and of
Spain, 240
CHAPTER XVI. The Glass of Germany. The Green Glass of the Rhine and
the Netherlands—Enamelled Glass, 251
CHAPTER XVII. The Glass of Germany (_continued_). German Cut and
Engraved Glass—The Ruby Glass of Kunckel—_Milch_ Glass, 276
CHAPTER XVIII. Dutch Glass of the Seventeenth and Eighteenth
Centuries, 294
CHAPTER XIX. English Glass of the Sixteenth and Seventeenth
Centuries, 299
CHAPTER XX. English Glass of the Eighteenth Century, 321
CHAPTER XXI. The Seventeenth and Eighteenth Century Glass of
Persia, India, and China, 337
CHAPTER XXII. Contemporary Glass, 356
INDEX, 361
LIST OF ILLUSTRATIONS
I. SYRIAN OR VENETIAN GLASS. Enamelled Beaker of slightly
greenish glass with a few elongated bubbles. (H. 7-1/2 in.)
The Virgin and Child enthroned between conventional lilies;
on either side an angel holding a tall candle; beyond, the
figures of St. Peter and St. Paul. Above, an inscription in
Gothic characters—D[=N]IA MATER REGIS ALTISSIMI ORA P PA.
From the Adrian Hope collection. End of thirteenth century.
British Museum. (_Frontispiece._)
II. UNGUENTARIA OF PRIMITIVE GLASS. British Museum.
(1) From Gurob, near Illahun, Upper Egypt. (H. 4 in.)
Decoration of palm-pattern formed by double drag, on a
sard-coloured translucent ground. Nineteenth Dynasty.
(2) Amphora-shaped vase. (H. 5-3/8 in.) Pattern formed by
simple drag, on opaque red ground. The body apparently turned
on wheel. Handles of green transparent glass. Said to come
from the Ionian Islands.
(3) Small Jug of Oenochoë shape. (H. 5-1/2 in.) Palm pattern
formed by double drag, on dark blue, nearly opaque ground.
_Provenance_ uncertain. From the Slade collection.
(_To face p. 22._)
III. EGYPTIAN GLASS PASTES. British Museum.
(1) Scarab of dark blue paste with white veins
imitating _lapis lazuli_. (L. 3-1/2 in.) From Thebes.
Later Empire.
(2) Vase for cosmetics, in shape of column with papyrus
capital. (H. 3-3/4 in.) Slade collection.
(3) Plaque of ‘fused mosaic.’ (L. 3-1/4 in., about 3/8 in. in
thickness.) From the cemetery at Denderah. Ptolemaic period.
(_To face p. 32._)
IV. (1) Small bottle (‘lachrymatory’). (H. 3 in.) Glass of
various colours arranged in wavy lines, and now in part
iridescent. Probably from a Greco-Roman tomb. Slade
collection.
(2) Bowl of thin white glass, finished on the lathe. (Diam.
3-3/4 in.) Probably from a late Greek tomb.
(3) Spherical vase of pale blue transparent glass. (H.
3-3/8 in.) The mark of the two parts of the mould into which
the glass was blown is visible. Decoration of dolphins,
fishes, etc., on bands. Probably Roman, first century A.D.
Slade collection. 1, 2, and 3, all in British Museum.
(_To face p. 45._)
V. TWO BOWLS OF MILLEFIORI ROMAN GLASS. Probably Roman, first
century A.D. British Museum.
(1) Madrepore pattern, in dark purple ground. (Diam. 5 in.)
(2) Breccia pattern, in purple ground with white scrolls.
From the Durand collection. (Diam. 5-1/4 in.)
(_To face p. 50._)
VI. (1) Beaker with oval bosses, formed by blowing into a mould
with apertures. (H. 5 in.) Clear white glass. Said to have
come from Constantinople. Greco-Roman, first century A.D.
(2) Tall-necked flask of pale green transparent glass. (H.
6-3/4 in.) Maze-like pattern, formed by blowing into mould.
Greco-Roman. From Melos.
(3) Small octagonal pyx, or case for cosmetics. (H.
6-1/4 in.) White opaque glass (but probably originally
transparent); blown into mould. From Sidon. Probably first
century B.C. 1, 2, and 3, all in British Museum.
(_To face p. 56._)
VII. SEPULCHRAL GLASS FROM THE SYRIAN COAST (said to come from
Mount Carmel). Probably about first century B.C. Pale green
glass, with iridescence. British Museum.
(1) Vase for cosmetics in shape of double column. (H.
5-1/4 in.)
(2) Vase with six handles. (H. 4-1/4 in.)
(3) Vase with handles and stringings of cobalt-blue. (H.
8 in.) (_To face p. 60._)
VIII. BOWL OF OLIVE-GREEN GLASS, carved in high (detached) relief.
Mounted on metal stand and with metal rim. Deep red by
transmitted light. Subject—The Madness of Lycurgus. Probably
Roman, about third or fourth century A.D. From the collection
of Lord Rothschild. (_To face p. 73._)
IX. ROMAN GLASS FROM GRAVES IN BRITAIN. British Museum.
(1) Jug of pale olive glass, with iridescence. (H. 8-3/8 in.)
From Colchester.
(2) Vase of olive-green glass, with two handles, each ending
in quilled attachments. (H. 9 in.) From Bayford, near
Sittingbourne. (_To face p. 86._)
X. GILT GLASS OF THE CEMETERIES. Fifth century A.D. British
Museum.
(1) Part of a bowl, the sides ornamented with small
medallions of gilt glass. Subjects—Adam and Eve, Sacrifice
of Isaac, Jonas, the Three Children, Daniel, etc. (Max.
dimension, 6-1/2 in.) Found near the Church of St. Severinus,
Cologne.
(2) Disc from base of bowl. (Diam. 3-3/4 in.) Below, Christ,
between Timothy and Hippolytus; above, St. Paul, St. Sixtus,
and St. Laurence, standing between torque columns.
(3) Portraits of Bride and Bridegroom—Orfitus and
Constantia; with figure of Hercules and congratulatory
inscription. (Diam. 4 in.) (_To face p. 91._)
XI. BYZANTINE GLASS, from the Treasury of St. Mark’s, Venice.
(Reproduced from Passini, _Tesoro di S. Marco_.)
(1) ‘Balance-pan’ lamp of clear glass for suspension. On the
silver rim, an invocation to St. Pantaleone by the Bishop of
Iberia. (Diam. 10-1/2 in.)
(2) Ellipsoid lamp, for suspension. Common glass, carved in
high relief with shells, fishes, etc. Silver rim, with
cloisons for jewels and sockets for candles. (Chief diam.
8 in.)
(3) Paten, or more likely ‘balance-pan’ lamp. Greenish glass,
incised with a series of concentric rings. (Diam. 7 in.)
(_To face p. 96._)
XII. CANTHARUS-SHAPED VASE of sky-blue, bubbly glass. (H.
6-1/4 in.) Probably a chalice. _Circa_ fifth century A.D.
Found at Amiens. From the Pourtalès collection. British
Museum. (_To face p. 98._)
XIII. BYZANTINE OR EARLY SARACENIC GLASS, from the Treasury of St.
Mark’s, Venice. (Reproduced from Passini, _Tesoro di S.
Marco_.)
Pear-shaped vase, set with ‘false’ metal spout and handle, to
resemble an ampulla. Carved in low relief, in imitation of
rock-crystal—design of two sheep-like animals amid
conventional foliage. (Glass alone 4 in. in H.)
(_To face p. 101._)
XIV. BYZANTINE OR LATE ROMAN GLASS, from the Treasury of St.
Mark’s, Venice. (Reproduced from Passini, _Tesoro di S.
Marco_.)
_Situla_ of greenish glass, carved in high (detached) relief
with a hunting scene. Below, a raised grating, supported on
rods of glass (_diatretum_ work). H. 11 in.
(_To face p. 102._)
XV. GLASS BEADS. British Museum.
(1) Cylindrical beads with white and yellow pellets: (i) Blue
glass with satyr-like mask; (ii) opaque greenish glass.
Probably from Cyprus. Greek or Phœnician.
(2) Two Chevron beads. _Provenance_ uncertain. Slade
collection.
(3) Three chains of beads, from Frankish tombs in the
Rhine-Moselle district. (_To face p. 108._)
XVI. ANGLO-SAXON GLASS. Prunted Beaker of olive-green glass.
(H. 11-1/8 in.) From burial-mound, Taplow. British Museum.
(_To face p. 111._)
XVII. ANGLO-SAXON GLASS. (1) Conical cup of pale green glass, with
applied threadings. (H. 10-1/4 in.) From Kempston,
Bedfordshire. British Museum.
(2) Drinking-cup of olive-green glass. (H. 8-1/2 in.) From
Faversham, Kent. British Museum (Gibbs Bequest).
(_To face p. 112._)
XVIII. HEDWIG GLASS (so-called). Two views of a cup of nearly
colourless glass (H. about 4 in.), carved in relief with
lion, griffin, and shield. German or Oriental; thirteenth
century, or perhaps earlier. Now mounted on Gothic metal
stand, which is not shown. Germanic Museum, Nuremberg.
(_To face p. 114._)
XIX. MEDIÆVAL GLASS FURNACE. Reproduction of a coloured miniature
from a manuscript, written probably in 1023, of Rabanus Maurus
(_De Originibus Rerum_), preserved in the library at Monte
Cassino. (_To face p. 124._)
XX. GERMAN GLASS, FOURTEENTH AND FIFTEENTH CENTURY. Dark
bluish-green glass, from the Germanic Museum, Nuremberg.
(1) Prunted cup for holding relics.
(2) Wax cover to above, with seal of the Abbey to which it
belonged. (_To face p. 137._)
XXI. Do. do.
(1) Small cup with pap-shaped prunts.
(2) Cup with conical cover, containing relics.
(_To face p. 137._)
XXII. SARACENIC GLASS. Pilgrim bottle; brownish, amber-coloured
thick glass, enamelled and gilt. (H. about 8 in.) On the
flattened back a rose-wheel design. Long preserved at
Würzburg; said to come from Mesopotamia. _Circa_ 1300 A.D.
British Museum. (_To face p. 153._)
XXIII. SARACENIC GLASS. Tall-necked bottle; decorated with enamelled
and gilt medallions, Chinese phœnix, etc. (H. 17-1/2 in.) The
inscription has been read ‘Glory to our Lord the Sultan, the
wise, the just, the warrior King.’ Bought in Cairo. _Circa_
1300 A.D. Victoria and Albert Museum (Myers Bequest).
(_To face p. 154._)
XXIV. SARACENIC GLASS. Victoria and Albert Museum.
(1) Small lamp of clear white glass, a little decayed on
surface. (H. 8-1/4 in.) Enamels of white, red, and yellow
with gold, sparingly applied—horsemen with falcons; gold
frieze on rim and foot. Stated to have come from a Christian
monastery in Syria. Late thirteenth or early fourteenth
century. Myers Bequest.
(2) Vessel for oil. Probably to be suspended in a large
mosque lamp (lantern). (H. 6-1/2 in.) Pale greenish-blue
glass, with remains of the gilding that formerly covered it.
(_To face p. 156._)
XXV. SARACENIC GLASS. Beaker enamelled with frieze of three
polo-players, between two bands with inscription in Arabic,
both in praise of ‘our Lord the Sultan’ (without date or
proper name). About 1300. The silver-gilt foot and cover are
probably Augsburg work of the early sixteenth century. From a
reproduction in water-colours of the original in the _Grüne
Gewölbe_, Dresden. (_To face p. 162._)
XXVI. SARACENIC GLASS. Mosque lamp (H. 16 in.) from Cairo. Clear
white glass with many bubbles. Eight handles for suspension.
Design of lotus-blossom, etc., outlined in opaque red, and
the interstices filled with translucent blue enamel. Early
fourteenth century. Victoria and Albert Museum (Myers
Bequest). (_To face p. 168._)
XXVII. (1) DRINKING-CUP (Diam. 5-1/2 in.) of honey-coloured glass.
In centre, enamelled figure of ‘the angel who serves the wine
to the faithful.’ Angel’s wings and surrounding band, gold
upon a lavender-blue ground. Persian in style, but according
to M. Schefer, possibly made at Ermenas and enamelled at
Aleppo. Probably fifteenth century. British Museum.
(2) HOLLOW SPHERE of honey-coloured enamelled glass.
(Diam. 4 in.) Ornament of chain of mosque lamp. _Provenance_
unknown, but probably from Northern Syria. British Museum.
(_To face p. 172._)
XXVIII. VENETIAN GLASS. The Aldrevandini Beaker. (H. 5-1/8 in.) Thin
clear glass with black specks, enamelled with three shields
bearing the arms of South German towns: (1) Three stag-horns
in fesse, azure; (2) argent, three keys in fesse, gules; (3)
per fesse argent and sable, in chief a bar. Between,
apple-green leaves outlined in white. Some enamelling also
inside. Inscription in Gothic letters. About 1300 A.D.
British Museum. (_To face p. 179._)
XXIX. VENETIAN GLASS. The Berovieri Cup. (H. c. 8-1/2 in.) _Coppa
Nuziale_ (marriage cup) of deep-blue glass, enamelled and
gilt. The heads of bride and bridegroom in medallions.
Between, (1) a procession of knights and ladies approaching
a fountain; (2) bathing in fountain. Attributed to Angelo
Berovieri. About 1440. Museo Civico, Venice.
(_To face p. 194._)
XXX. VENETIAN GLASS. (1) Lamp for suspension, enamelled with studs
of white on coloured ground. (H. 11 in.) Shield with _stemma_
of Tiepolo family. Early sixteenth century. Museo Civico,
Venice.
(2) Stemless cup of thin clear glass. (H. 5-1/2 in.)
Decorated with scrolls, lions, and birds, in ‘painted’
enamel. About 1450. Dug up while excavating the foundations
of the new Campanile. Museo Civico, Venice.
(_To face p. 199._)
XXXI. VENETIAN GLASS. Flower-vase. (H. 11 in.) Transparent,
colourless glass, slightly greyish, with tendency to
deliquescence on surface: threading and studs of
cobalt-blue. Probably sixteenth century. British Museum.
(Slade, _ex_ Bernal collection.) (_To face p. 200._)
XXXII. VENETIAN GLASS. Spherical vase (H., with ‘made-up’ foot,
9-1/2 in.) of opaque white glass, decorated with gilt scrolls
and bosses and a pair of rudely drawn mermaids. Sixteenth
century. British Museum. (Slade, _ex_ D’Azeglio collection.)
(_To face p. 203._)
XXXIII. VENETIAN GLASS. Pilgrim’s bottle. (H. 6-1/2 in.) Design
(Cupid fishing, and Venus and Anchises) painted in blue on
opaque white (_lattimo_) ground. Early sixteenth century.
Museo Civico, Venice. (_To face p. 204._)
XXXIV. VENETIAN GLASS, enamelled and gilt. Early sixteenth century.
British Museum.
(1) Plate of thin glass. (Diam. 7 in.) In centre a shield
with oak tree, green and gold on blue ground. (? Rovere
arms.) Round margin a ring of delicate pattern in powder
gold. Early sixteenth century. (Slade collection.)
(2) Tazza of thin glass. (Diam. 6 in.) Coat of arms in
lozenge in centre, surrounded by ring with flowers in oval
medallions—apple-green, dull red, blue and yellow enamels.
Powder gold band round margin. (Slade, _ex_ Bernal
collection.) (_To face p. 214._)
XXXV. FRENCH GLASS OF RENAISSANCE. British Museum. (Slade
collection.)
(1) Statuette of Louis XIII. or XIV. (H. 4-1/4 in.) Opaque
white glass with coloured enamels. Probably made at Nevers.
Seventeenth century.
(2) Statuette of man with muff. (H. of figure, 5 in.) Opaque
white, porcelain-like glass, on a copper base. On stand of
white Dresden china, partly gilt.
(3) Small burette (H. 5 in.) of dark greenish-blue
transparent glass; the body and neck splashed with green,
white, and red enamels. Gilt berry-like bosses on body.
Probably sixteenth century. (_To face p. 233._)
XXXVI. SPANISH GLASS. Victoria and Albert Museum.
(1) Vase of pale bottle-green glass; four handles with
quilled edges. (H. 6-1/2 in.) From the South of Spain.
Sixteenth or seventeenth century.
(2) Jug of white transparent glass (H. 8-1/2 in.), made at
S. Ildefonso.
(3) Vase of transparent glass, slightly greenish. (H. 6 in.)
Two handles with quilled edges. From the South of Spain.
Sixteenth or seventeenth century. (_To face p. 245._)
XXXVII. GERMAN GLASS. Roemer of green glass; berry prunts on waist;
the foot built up of glass stringing. _Circa_ 1600. Germanic
Museum, Nuremberg. (_To face p. 254._)
XXXVIII. GERMAN GLASS FURNACE. Sixteenth century. From Agricola,
_De Re Metallica_, Basle, 1556. (_To face p. 260._)
XXXIX. GERMAN GLASS. _Willkomm Humpen_, enamelled in colours with
the _Reichs-adler_. On the wings, as recorded by an
inscription on the back, the arms of the various members of
the Holy Roman Empire. Dated 1656. Greenish glass; below
margin, a ring of ‘powdered’ gold, between beading of white
and blue enamel. British Museum (Henderson Bequest).
(_To face p. 264._)
XL. GERMAN GLASS. British Museum.
(1) Beaker of clear white glass. (H. 5-1/2 in.) Enamelled
with double eagle, white and blue, with yellow beaks and
claws; at the back a sprig of lily-of-the-valley. Dated 1596.
From the Bernal collection.
(2) Jug of pale purple glass (H. 8 in.) with pewter lid.
Enamelled with a white dog pursuing a red stag and fox. In
addition green, blue, and yellow enamels. Dated 1595. From
the Slade collection. (_To face p. 267._)
XLI. GERMAN GLASS. _Willkomm Humpen._ Enamelled in colours with
hunting scene, the game being driven into net. About 1600.
British Museum. (_To face p. 268._)
XLII. GERMAN GLASS. Covered beaker of clear white glass. (H. with
cover 6-3/4 in.) Engraved with design of _amorini_ dancing
among vines. The metal knob of cover is enamelled and gilt,
and on the interior button are enamelled the arms of the
Archbishop of Trèves, with the following inscription:—Joan
Hugo D.G. Arc. Trev. PR. EL. EP. SP. Early eighteenth century.
(_To face p. 283._)
XLIII. DUTCH GLASS. Beaker in the form of a _roemer_. (H. 9 in.) On
the bowl, in medallions, heads symbolising the four seasons,
scratched with the diamond. The waist, decorated with berry
prunts, showing remains of gilding. On this part is scratched
(in English) ‘August the 18th, 1663,’ and the letters H./W.E.
between bay branches. On the foot a landscape with hunting
scene. British Museum. (_To face p. 296._)
XLIV. ENGLISH WINE-GLASSES. British Museum.
(1) Wine-glass, early eighteenth century. (H. 8-3/4 in.) The
hollow knop of the moulded stem is decorated with prunts and
encloses a sixpence of Queen Anne (dated 1707).
(2) Jacobite wine-glass with opaque twisted stem. (H.
7-3/4 in.) On the bowl is engraved a portrait of the Young
Pretender, inscribed ‘_Cognoscunt me mei_’; at the back are
the words _Premium Virtutis_ under a crown.
(3) Jacobite wine-glass with air-twisted stem. Round the bowl
are engraved the words ‘Immortal Memory’; above, a band of
vine-leaves, and below, fleurs-de-lis and roses. Presented by
Mr. A. Hartshorne. (_To face p. 327._)
XLV. ENGLISH FLINT GLASS. Victoria and Albert Museum.
(1) Standing cup and cover (H. 12 in.) on square, stepped
foot. Carved in relief with gadroons descending spirally. End
of eighteenth century. Presented by Mr. H. B. Lennard.
(2) Bowl standing on square base. (H. 8-1/2 in.) The whole of
the surface facetted; the under surface of the foot cut into
square compartments. End of eighteenth century. Presented by
Mr. H. B. Lennard. (_To face p. 332._)
XLVI. PERSIAN GLASS. Tall-necked vase of colourless glass; body
shaped in a mould; _appliqué_ stringings on foot. Taken from
a tomb at Baku. Vincent Robinson collection.
(_To face p. 338._)
XLVII. PERSIAN GLASS. Victoria and Albert Museum. Seventeenth or
eighteenth century.
(1) Tall-necked, pear-shaped vase, the surface spirally
ribbed, of deep blue transparent glass. (H. 11 in.)
(2) Cruet-shaped vase of clear white glass. (H. 9 in.) From
the Richard collection.
(3) Perfume sprinkler, with curved neck and barnacle-shaped
lip. Blue transparent glass, the surface spirally ribbed.
(H. 12 in.) (_To face p. 340._)
XLVIII. INDIAN GLASS. Indian Museum. Vase or basin with
wide-spreading lip. (H. 5-3/4 in.) Milky, semi-transparent
glass; the ground gilt, surrounding white flowers, with
pistils of red enamel. _Provenance_ unknown. (Delhi
district?) (_To face p. 343._)
XLIX. CHINESE GLASS. Victoria and Albert Museum.
(1) Bowl of mottled green glass with purple markings,
imitating jade. (H. 2-7/8 in.) Eighteenth century. From the
Bernal collection.
(2) Spindle-shaped vase of orange, ‘tortoise-shell’ glass.
(H. 7-1/2 in.) The stopper of silver, inlaid with Chinese
characters; the base European.
(3) Small tripod vase of mottled yellow glass, in form of
incense-burner. (H. 3-3/4 in.) Eighteenth century.
(_To face p. 350._)
SELECTED BIBLIOGRAPHY OF WORKS ON GLASS
AGRICOLA (GEORG): _De Re Metallica_ (last chapter of work). Basle, 1556.
APPERT (L.) ET HENRIVAUX: _Verre et Verrerie_. Paris, 1894.
APPERT (L.): _Notes sur les verres des Vitraux Anciens_. Paris, 1896.
BAPST (A.): _Chinesische Glasarbeiten; Zeitschrift für Bildende Kunst_,
1885.
BATE (PERCY): _English Table-Glass_. No date. (1904?)
BIRINGUCCIO (V.): _De la Pirotechnia_. Venice, 1540.
BLANCOURT (HAUDICQUER DE): _L’Art de la Verrerie_. Paris, 1697.
BONTEMPS (G.):—
_Guide du Verrier_. Paris, 1868.
_Exposé des moyens employés pour la fabrication des Verres
Filigranés_. 1845.
BORDONI: _L’Arte Vetraria in Altare_. Savona, 1884.
BOSC D’ANTIC (P.): _Mémoires sur l’Art de la Verrerie_. Paris, 1780.
BOUTELLIER (L’ABBÉ): _Histoire des Gentilshommes Verriers de Nevers_.
BRENT (JOHN): ‘On Chevron Beads.’ _Archæologia_, vol. xlv.
BRINCKMANN (JUSTUS): Various Catalogues, etc., of the Hamburg Museum.
BUCHER (B.): _Die Glassammlung des K.K. Oesterreich. Museum_. Vienna,
1888.
BUSHELL (S. W.):—
_Oriental Ceramic Art_. New York, 1899.
_Chinese Art_, vol. ii. (South Kensington Art Handbooks). 1906.
BUSSELIN (D.): _Les Célèbres Verreries de Venise_. Venice, 1846.
CECCHETTI:—
_Delle Origini dell’ Arte Vetraria Muranese_. R. Institute Veneto,
1872.
_Monographie dell’ Arte Vetraria._ Venice, 1874.
CZIHAK (E. VON): _Schlesische Gläser_. Breslau, 1891.
DALTON (O. M.):—
_Catalogue of Early Christian Antiquities in the British
Museum—Cemetery Glasses_. 1901.
‘Gilded Glass of Catacombs.’ _Archæological Journal_, 1901.
DEVILLE (A.): _Histoire de l’Art de la Verrerie dans l’Antiquité_.
Paris, 1873.
DOBBS (H. C.): ‘Glass-blowers of North-west Provinces.’ _Journal of
Indian Art_, vol. vii.
ERACLIUS: _see_ HERACLIUS.
FILLON (B.): _L’Art de Terre chez les Poitevins_. Niort, 1864.
FIORAVANTI (L.): _Dello Specchio di Scienza Universale_, Bk. vii. cap.
29. Venice, 1567.
FOURCAUD (L. DE): _Émile Gallé_. Paris, 1903.
FOWLER (J.): ‘On the Process of Decay in Glass.’ _Archæologia_, vol.
xlvi.
FRANKS (SIR A. W.):—
_Guide to Glass Room in British Museum_, 1888.
_Art Treasures of United Kingdom. Vitreous Art._ 1858.
FRIEDRICH (C.): _Die Altdeutschen Gläser_. Nürnberg, 1884.
FROEHNER (W.): _La Verrerie Antique_. _Collection Charvet_, 1879.
GARNIER (E.):—
_Histoire de la Verrerie et de l’Émaillerie_. Tours, 1886.
_Spitzer Catalogue_, vol. iii. ‘La Verrerie.’
GARRUCCI (P. R.):—
_Storia dell’ Arte Christiana_, vol. iii. 1876.
_Vetri ornati di Figure in Oro._ 1858 and 1864.
GARZONI (T.): _Piazza Universale di tutte le professioni del Mondo_.
Discorso lxiv. Venice, 1585.
GERSPACH: _L’Art de la Verrerie_. Paris, 1885.
GRIFFITH (F.): _Egypt Exploration Fund_. Tanis, Part ii. 1888.
HALLEN (REV. A.): ‘Glass-making in Sussex, etc.’ _Scottish Antiquary_,
1893.
HARTSHORNE (ALBERT): _Old English Glasses_. 1897.
HAVARD (H.): _Les Arts de l’Ameublement_. _La Verrerie._ Paris, 1894.
HERACLIUS or ERACLIUS: _De Artibus et Coloribus Romanorum_. Eitelberger
von Edelberg: _Quellenschriften für Kunstgeschichte_, vol. iv.
HIRTH (F.): _Chinesische Studien_; _Zur Geschichte des Glases in
China_. Leipsic, 1890. And other papers.
D’HOLBACH (BARON)?: _Art de la Verrerie, de Neri, Merret et Kunckel_.
Paris, 1752.
D’HONDT (P.): _L’Art de la Verrerie_. Liége, 1891.
HOUDOY (J.): _Verrerie à la façon de Venise_. Paris, 1873.
KUNCKEL (J.): _Ars Vitraria Experimentalis_. 1679.
LABARTE (J.):—
_La Collection Debruge Duménil_. Paris, 1847.
_Histoire des Arts Industriels_, vol. iv. Paris, 1866.
LACROIX (P.): _Les Arts au Moyen Âge et à l’Époque de la Renaissance_.
Paris, 1869.
LANE-POOLE (S.):—
_The Art of the Saracens in Egypt_. London, 1886.
_Arabic Glass Weights in British Museum_. 1891.
LAYARD (SIR A. H.): _Nineveh and its Remains_. 1853.
LAZARI (V.): _Notizia delle Opere d’Arte della Raccolta Correr_.
Venice, 1859.
LOBMEYR (L.): _Die Glas-industrie_. Stuttgart, 1874.
LOYSEL (C.): _Essai sur la Verrerie_. Paris, 1800. (Written earlier.)
MATHESIUS: _Sarepta oder Bergpostil_ (Sermon xv.). Nürnberg, 1562.
MERRET (C.): _The Art of Glass of Neri translated into English_.
London, 1662.
MILANESI (G.): _Tre Trattatelli dell’ Arte del Vetro per Mosaici_.
(Fifteenth century MSS.) 1864.
MINUTOLI (H. DE): _Ueber der Anfertigung der farbigen Gläser bei den
Römern_. Berlin, 1836.
MOLINIER (E.): _La Peinture sous Verre_. _Spitzer Catalogue_, vol. iii.
NAPLES: _Description of Museo Borbonico_. _Glass_, vols. v., xi., and
xv.
NERI (A.): _L’Arte Vetraria_. 1612.
NESBITT (A.):—
_Catalogue of Slade Collection of Glass_. Privately printed, 1871.
_Catalogue of Glass Vessels in South Kensington Museum_, 1878.
_Glass_ (South Kensington Art Handbooks), 1875.
‘Opus Sectile in Glass.’ _Archæologia_, vol. xlv.
_Encyclopædia Britannica_, article ‘Glass.’ 1879.
OWEN (H.): _Ceramic Art in Bristol_ (chapter on Bristol Glass). 1873.
PASSINI (A.): _Il Tesoro di San Marco_. Venice, 1886.
PELIGOT (M. E.): _La Verre, Histoire et Fabrication_. 1876.
PELLAT (APSLEY):—
_Curiosities of Glass-making_. London, 1849.
_Memoir on the Origin, etc., of Glass-making_. London, 1821.
PELLETIER: _Les Verriers du Lyonnais_. 1887.
PETRIE (FLINDERS):—
_Burlington Fine Arts Club; Introduction to Catalogue of Egyptian
Exhibition_, 1895.
_Tell-el-Amarna_. _Egypt Exploration Fund_. 1894.
PINCHART (A.): _Les Fabriques des Verres de Venise, d’Anvers et de
Bruxelles au XVI^e. et au XVII^e. siècles_. _Bulletins des
Commissions Royales_. Bruxelles, 1882.
PLINIUS SECUNDUS (CAIUS): _Historia Naturalis_, Bk. xxxvi. caps. 44-47.
PORTER (G. R.): ‘Glass and Porcelain.’ _Lardner’s Cabinet
Encyclopædia_. London, 1832.
POWELL (H. J.):—
_Principles of Glass-making_. London, 1883.
_Encyclopædia Britannica_, article ‘Glass.’ 1902.
READ (C. H.):—
‘Glass in South Saxon Graves.’ _Archæologia_, vol. lv.
‘On a Saracenic Goblet of Enamelled Glass.’ _Archæologia_, vol. lviii.
RIAÑO (J. F.): _Industrial Arts in Spain_, Part ii. (South Kensington
Handbooks). 1879.
SANTI (M.): _Origini dell’ Arte Vetraria in Venezia e Murano_.
SAUZAY (A.):—
_La Verrerie depuis les Temps les plus reculés_. Paris, 1868.
SAUZAY (A.):—
_Marvels of Glass-making_. (Translation of above.) London, 1870.
SCHEBEK (E.): _Böhmens Glasindustrie und Glashandel_. Prague, 1878.
SCHMORANZ (G.): _Old Oriental Gilt and Enamelled Vessels_. German and
English Editions. Vienna and London, 1899.
SCHUERMANS (H.): _The Wanderings of the Muranese and Altarist
Glass-workers. Eleven Letters_. _Bulletins des Commissions Royales_.
Bruxelles, 1883-1891.
_Spitzer Catalogue_. _See_ GARNIER and MOLINIER.
THEOPHILUS: _Diversarum Artium Schedula_. Eitelberger von Edelberg.
_Quellenschriften für Kunstgeschichte_, vol. viii. Vienna, 1874.
URE (A.): _Dictionary of Arts_, article ‘Glass.’ 1853.
VOPEL (H.): _Die Altchristlichen Goldgläser_. Freiberg, 1899.
ZANETTI (V.):—
_Monographia della Vetraria Veneziana_. Venice, 1873.
_Museo Civico di Murano_; _Guida di Murano_. Venice, 1866.
KEY TO THE PRECEDING LIST
_Egyptian_, _etc._ Griffith, Layard, Petrie.
_Greco-Roman and Roman._ Deville, Froehner, Fowler, Minutoli, Naples
Museum, Nesbitt, Pliny.
_Early Christian_, _Byzantine_, _Anglo-Saxon_, _etc._ Brent, Dalton,
Garrucci, Heraclius, Passini, Read, Theophilus, Vopel.
_Saracenic and Perso-Indian._ Lane-Poole, Dobbs, Read, Schmoranz.
_Venetian_ (Murano and Altare). Biringuccio, Bontemps, Bordoni,
Busselin, Cecchetti, Fioravanti, Garzoni, Houdoy, Labarte, Lazari,
Neri, Pinchart, Santi, Schuermans, Zanetti.
_French and Spanish._ Boutellier, Fillon, Fourcaud, Gamier, Gerspach,
Pelletier, Riaño.
_German._ Agricola, Brinckmann, Von Czihak, Friedrich, Kunckel,
Lobmeyr, Mathesius, Schebek.
_English._ Bate, Hallen, Hartshorne, Merret, Owen, Pellat.
_Chinese._ Bapst, Bushell, Hirth.
_Technical._ Appert, Blancourt, Bontemps, Bosc d’Antic, D’Holbach,
Kunckel, Lobmeyr, Loysel, Merret, Neri, Peligot, Pellat, Porter,
Powell, Ure.
_General and historical._ Brinckmann, Franks, Garnier, Gerspach,
Havard, Labarte, Lacroix, Nesbitt, Sauzay.
GLASS
CHAPTER I
INTRODUCTION
Glass is a substance in so many ways connected with the conveniences
and amenities of our daily life, and the word calls up so many varied
associations, that I must here at the very beginning make clear with
what a comparatively small proportion of the manifold applications of
the substance I have to deal.
In the first place, this is an art history, so that with methods of
manufacture and practical uses we are only concerned so far as they may
influence or help to explain points of artistic interest. Again, even
on the artistic side, it is not with every branch of the varied
applications of glass that we shall be occupied in this work. By an
anomaly of the English language, whose vocabulary for matters connected
with the arts is so strangely deficient, we have come to understand by
the term ‘glass,’ when used without further explanation, what is called
in the trade ‘hollow ware,’ the _verrerie_ of the French; in other
words—vessels of glass. The term may also be extended to include
various minor applications of the material—beads, small ornaments,
etc., what the French call _verroterie_. But the application of glass
to windows, especially when coloured and stained glass is in question,
to say nothing of work in mosaic, is usually, although not always, held
to lie outside this narrower connotation of the word.
Now it happens that for us this restriction is in every way convenient.
For though the material basis is the same, it is evident that both the
artist who works in mosaic and the designer of stained windows are
concerned, each in his department, with artistic problems only
incidentally connected with the material in which they work. In other
words, the art element in both these crafts only becomes prominent at a
stage when the actual preparation of the glass is completed. It is,
however, certainly a pity that there is no English word which would not
only clearly connote the class of objects with which I have here to
deal, but which would at the same time distinctly comprise nothing
beyond.
I have now explained the somewhat restricted and artificial sense of
the word glass that I propose to accept in this work. But for a moment
let us pass to the other extreme, and going beyond the ordinary
connotation of the term include in it the glazes of pottery—the word
‘glaze’ is in its origin the same as glass—as well as the many forms
of enamel. In all these cases we are dealing with substances of similar
composition. They may all probably be traced back to a common origin,
so that from an evolutionary point of view we have here an instance of
the development of the complex and varied from the simple and single.
Looking at the question in another way, the art of the enameller, using
the term in a restricted sense, may be held to be subsidiary both to
that of the potter and of the glass-worker; while many of the problems
that arise in treating of the glazes of fictile wares—questions as to
fusibility, or as to the colours employed and the changes of these
colours during the firing—turn up again in the manufacture of glass.
We shall see that experience gained in following the processes of one
art may serve to throw light upon the difficulties and problems of the
other.
Historically the connection between glass and pottery is not so close.
In some degree the prevalence of one art has tended to oust the other,
or to relegate it to an inferior position. The Greeks, who carried the
potter’s art to such perfection, knew little about glass—it was long
an exotic substance for them. The Romans, on the other hand, who in the
first centuries of our era first fully appreciated and developed the
capacities of glass, produced little pottery of artistic interest. In
the sixteenth century, in Umbria and Tuscany, where the finest majolica
was made, we hear nothing of the manufacture of glass, while on the
other hand the fayence of Venice, at this time pre-occupied with her
glass, was of subsidiary importance. If we turn to the home of
porcelain, in China glass has always held a subordinate position, while
in Japan it was until recent days practically unknown.
Were a comparison to be made between the development of the various
minor arts, it would be difficult to find a wider contrast than that
between the history of porcelain and that of glass. The knowledge of
porcelain was confined for nearly a thousand years to China, the
country where it was first made, and where it was slowly brought to
perfection. Let loose, as it were, in the West early in the eighteenth
century, it had then a short period of glory, but before the end of the
century the art had already fallen upon evil days. The manufacture of
glass, on the other hand, had long been carried on in Egypt, and
perhaps in other Eastern lands, by a primitive process, although it
only became an article of general use after the discovery of the
blowing-iron. When and where this discovery was made we do not
know—perhaps somewhere in Syria or Mesopotamia, in the third or second
century before Christ. The art of blowing glass was known, no doubt, if
not fully developed, at the time when the kingdoms of the Ptolemies and
of the Seleucidæ fell under the rule of the Romans. By them it was
before long brought to perfection and carried into every corner of the
West, so that by the second or third century of our era the production
of glass in Europe was probably greater than at any subsequent time, at
least until quite recent days. Nor was the art of glass-making
completely extinguished by ‘the advance of the barbarians.’ Indeed,
some of the Germanic tribes not impossibly brought with them a
knowledge of the process not only of preparing but also of blowing
glass, picked up on their journeyings through East Europe, or perhaps
even learned in Western Asia. This was an instance of the passage to
the North and West of the arts of civilisation, by what we may call the
back-road of Europe, in opposition to the high-roads that led directly
from Italy by way of the Rhone and the Rhine.
But in the West the manufacture, though continuously carried on in many
spots, was after the fall of the Western Empire relegated to the
woods,—for nearly a thousand years little glass was produced of any
artistic interest. Indeed, but few examples of this forest or green
glass of the Middle Ages have survived to our time. During all this
long interval, in one direction only, in the West, was any advance
made. Within this period falls the great development of stained glass:
we must turn to the glorious windows of the cathedrals of France and
other Western lands, to see what the glass-workers of the time were
capable of producing. In the East, on the other hand, in the lands
ruled from Constantinople or influenced by Byzantine civilisation, what
we know of the glass of the early Middle Ages is almost confined to the
mosaic coverings of the walls of the contemporary churches. But just as
distinctly as the glass in the windows of the Gothic churches, this
mosaic work, for the reason we have already given, falls outside our
limits.
It was not till the end of the twelfth century that any important
advance was made in our narrower department of ‘hollow ware.’ Among
the many beautiful things made during that glorious season of
artistic production that had its start about this time in Egypt (or
perhaps, rather, in the lands between the Persian Gulf and the
Mediterranean)—except it be the inlaid metal work—there is nothing
that now interests us so much as the enamelled glass, the beautiful
ware that culminated in the magnificent Cairene mosque lamps of the
thirteenth and fourteenth centuries. The art of enamelling on glass
passed over to Venice in the fifteenth century, perhaps earlier, and
there in the next century the manufacture of the famous _cristallo_
was finally achieved, and complete mastery was obtained in the
working of this pure white glass. A fresh start was now given to the
industry in the north by means of the Venetian glass-workers, who
were sought for in every country to teach their new methods.
In Germany alone did some of the traditions of the old forest-workers
of ‘green-glass’ survive. By the end of the seventeenth century the
German glass, in some respects to be regarded as a compromise between
the old and new, had become the most important in Europe. For a hundred
years the products of ‘the mountain fringe of Bohemia’ held the premier
position, but towards the end of the eighteenth century this place was
taken by the facetted flint-glass of England. It is certainly
remarkable that it is only of quite recent years that any such
prominent position could be claimed for France, which heretofore had
been content to follow in the wake first of Venice and then of Germany
and of England. At the present day, however, this at least may be
said—that France is almost the only country where any really artistic
work in glass, apart from the reproduction of old patterns and old
methods, is being produced.
This hasty sketch of the history of glass-making will help us to
understand why it is that in following the development of the art in so
many lands, and for a period of more than three thousand years, there
is no need to linger for any time except at a few of the more important
_étapes_. Indeed such a procedure is forced upon us, for much of the
road is quite barren, other parts are unexplored, while for whole
stages we pass through prosaic districts where we find little of
artistic merit to detain us.
The periods, then, of real importance in the history of glass, either
from the _cultur-historisch_ or from a purely artistic point of view,
are separated by long intervals, during which little of interest was
produced. The primitive glass of Egypt, the varied productions of the
first centuries of the Roman Empire, the enamelled glass of the
Saracens, and the Venetian glass of the Renaissance—this exhausts all
that we find either of commanding historic interest or of superlative
artistic merit. What follows—the German and the Netherlandish glass of
the seventeenth and eighteenth centuries—is still of some importance
under both these heads. I can hardly say so much of the English glass
of the eighteenth century; but this glass must not be neglected—it is
English, and it is highly prized by many enthusiastic collectors.
It will be seen that there is a long gap between the first and second
of our critical periods—between the beginning of the primitive
Egyptian and the earliest Roman glass. This gap will be filled, in some
measure, by some account of the rare surviving specimens of glass that
can claim an Assyrian origin, of the glass pastes of the Mycenæan age,
and of the few examples of glass that can be strictly classed as Greek
of the classical age. So again of the second long hiatus—the interval
of nearly a thousand years between the period of the Roman glass and
that of the Saracens,—this may be partly filled by the few scanty
pieces that have come down to us from Sassanian and Byzantine times. To
this period belongs also the glass of the Germanic tribes of northern
Europe, above all that of our Anglo-Saxon ancestors.
Some notice must also be taken of a few districts situated on bypaths,
of the glass from countries that lie away from the main centres of
production—these latter centres, I may note, until comparatively
recent times are mostly to be found in close connection with the basin
of the Mediterranean. To these outlying districts we must finally turn
to examine the glass of Persia, of India, and above all the glass of
China.
An interesting chapter, nay, a separate work, might be devoted to the
classification and history of a class of objects of which the
manufacture has been carried on continuously and with few changes from
the time of the Middle Empire in Egypt—of beads, I mean, and other
allied applications of glass, included in the French term _verroterie_.
But, however great the claims to attention of such objects, their
interest is rather archæological than artistic, and it will be
sufficient to treat of them incidentally along with the, for us, more
important class of ‘hollow ware’ produced with the aid of the
glass-blower’s tube.
PROPERTIES AND COMPOSITION OF GLASS
Christopher Merret, our earliest English writer on glass, sets down the
properties of the material under twenty-six heads, ‘by which we may
easily differentiate it from all other bodies.’ From these I will
select some four or five which will be sufficient for our purpose.
Thus, of glass, he says: ‘’Tis a concrete of salt and sand or stones.
’Tis artificial. It melts in a strong fire. When melted ’tis tenacious
and sticks together.... When melted it cleaves to iron, etc. ’Tis
ductile whilst red-hot, and fashionable into any form, but not
malleable, and it may be blown into a hollowness’ (_Art of Glass_,
1662). Here we have briefly expressed the real _differentiæ_ of glass.
It is rather by these properties than by any virtue of transparency or
of definite chemical composition that glass is to be distinguished from
all other bodies; and it is only by duly taking advantage of these
properties that the preparation of a vessel of glass is rendered
possible.
In passing from a liquid to a solid state there intervenes a viscous
stage when the glass may be gathered at the end of an iron rod; the
ductile, tenacious mass may now be drawn out into long threads, whose
length and fineness are only limited by the difficulty of maintaining
the requisite temperature. Again, if the rod upon which the mass is
gathered is hollow, the glass may be blown out into a vesicle or bulb,
the starting-point from which an endless variety of objects, bottles,
cups, tubes, or even flat sheets of glass, may be subsequently formed.
Until advantage was taken of this remarkable property of glass—its
capability, I mean, of being blown out into a hollow vesicle when in a
viscid condition—the art of the glass-maker was in a primitive stage.
We may compare the glass prepared without the aid of the
blowing-tube—that of the ancient Egyptians, for instance—to the
pottery made by hand before the invention of the potter’s wheel.
In dealing with the practical side of our subject—the materials from
which glass is made, how these materials are first fritted and then
fused together, and how the fused mass is subsequently dealt with—the
best plan will be to approach the questions in each case from the point
of view of the time and country. But as, on the one hand, for classical
times, our sources of information for these practical details are but
scanty, and as, on the other, I am not concerned with the industrial
developments of the nineteenth century, it will be well to postpone any
fuller treatment of such matters until I come to speak of the glass of
late Mediæval and Renaissance times. I shall then be able to make use
of contemporary accounts which will throw light on the processes of
manufacture.
A few preliminary notes on the chemical and physical properties of
glass may, however, not be out of place.
Glass, Merret tells us, is ‘a concrete of salt and sand or stones.’
This, in modern scientific language, we should express by saying that
it is a combination of silica with an alkali. But these substances
alone are not enough. You cannot make a glass fit for practical use
from a pure quartz sand with the addition of nothing else than a salt
of potash or soda. Such a glass—a simple alkaline silicate—would
indeed be transparent, but it would be difficult to work and very
fragile. In all cases there is need of a second base, and this, to
speak generally, should be either lime or oxide of lead. The latter
base we may for the present neglect; speaking generally, it is the
presence of lime that gives the working qualities and the requisite
toughness. These, then, are the essential materials for the preparation
of glass. Other substances may be present; alumina, for example, or one
or other of the oxides of iron, but as a rule the presence of these
latter bases is not desired—the glass would be better without them.
Putting aside, then, for the present the glass in which lead is a
constituent, as well as that in which the soda is replaced by potash,
it is remarkable how little difference of composition we find in
examples of glass of the most divergent origin. Let us compare the
composition of a Roman ‘lachrymatory’ with that of a piece of modern
English plate-glass. In a hundred parts we find—
Silica. Soda. Lime. Iron Oxide. Alumina.
Roman lachrymatory 71·5 16·5 8 1 2
English Plate-glass 72 17 6 2 2
These examples are indeed two extreme terms of a long but continuous
series. A sample of Saracenic glass of the fourteenth or of Venetian
glass of the sixteenth century, would yield on analysis much the same
result.[1]
This, then, may be regarded as the normal composition of such glass as
I shall have to deal with in this history. The main question has
generally been—How can the sand or silica, the premier element in
glass, be best converted into a substance which shall in external
aspect resemble as closely as possible the native rock crystal (itself
pure silica), but which at the same time shall be not only fusible, but
after fusing pass on cooling through a plastic condition when it may be
expanded into a vesicle and otherwise worked up into various shapes?
Long practical experience has shown that this can be best effected by
adding to the sand materials containing both soda and lime, and as far
as possible nothing beyond these bases. A glass thus compounded we may
take as our normal type, but, as I have said, the soda may in certain
cases be replaced by potash and the lime by lead oxide.
Silica in any case is the essential element in glass, and in any normal
glass there may be present from 60 to 75 per cent. If, however, the
bases with which it is combined have a high combining number—and this
is especially the case with lead—the percentage of silica may fall
below the former figure. Thus, in a bottle glass with 12 per cent. of
iron oxide and alumina[2] the proportion is reduced to 54 per cent.,
and in a flint glass with 43 per cent. of lead oxide there is only 45
per cent. of silica.
It was once the fashion among English writers on glass to classify the
substance under the heads of crown-glass, bottle-glass, broad-glass,
plate-glass, flint-glass, etc.; but such a classification, not very
logical in itself, would be of no use to us.[3]
Glass, of course, varies in optical properties, in hardness, and in
fusibility, but I do not think that any useful classification could be
based directly on these properties. But there is one distinction of the
greatest importance technically and geographically, and this is between
the glass of maritime countries in which the alkali is soda, and that
of inland and forest districts where the soda is replaced by potash. In
the first group, by far the most important—I have indeed regarded such
glass as the normal type—may, it would seem, be placed not only the
‘primitive’ glass of the Eastern Mediterranean, but probably all the
glass of the Romans. To it belongs also the glass of the Saracens and
the greater part of the artistic glass of the Renaissance, including
the Venetian glass, although in this last the soda is often in part
replaced by an appreciable quantity of potash. The potash group, on the
other hand, includes the old _voirre à fougère_ of the French and the
_wald-glas_ of the Germans. In addition, almost the whole of the glass
of higher quality made in later days in Germany and in the Bohemian
borderlands belongs essentially to this last class. Finally, it may be
mentioned that in the case of the abnormal family where the lime is
replaced by oxide of lead, the alkali is invariably potash. Of this
family our English flint-glass is the most important member.
With regard to the hardness of glass, Merret mentions as the thirteenth
property possessed by that substance, ‘that it only receives sculpture
or cutting from a _Diamond_ or _Emery_ stone.’ But such a statement
would be likely to give an exaggerated idea of the hardness of glass.
If we take the scale of hardness used by the mineralogist, it will be
found that there are few kinds of glass that do not fall between the
fifth and sixth divisions of that scale. In other words, it would be
difficult to find a specimen of glass on which a crystal of apatite
(phosphate of lime) would make any impression, whereas all glass in
ordinary use is readily scratched by felspar. It is possible, however,
that some kinds of Bohemian glass may equal the latter mineral in
hardness; it is indeed a common statement that certain Bohemian or
German ‘combustion-tubes’ will strike fire with steel. On the other
hand, the presence of lead tends to make a soft glass; our cut flint is
perceptibly softer than common window-glass, and perhaps the most
important defect of the paste used to imitate precious stones—such
paste may contain as much as 50 per cent. of lead oxide—is to be found
in its comparative softness.
At the same time, the greater the amount of lead in a glass, the
greater its dispersive power on the light that passes through it. Hence
the brilliancy and fire of flint-glass, and still more of artificial
gems.
Apart from the varieties containing lead, samples of glass differ
little in weight; the specific gravity may range between 2·4 and 2·8.
That of flint-glass, on the other hand, varies from 3 to 3·8; indeed in
some optical glasses containing a large percentage of lead, and again
in the paste used for false jewellery, the specific gravity may be as
high as 4·5 or even 5.
The high melting-point, or more definitely the high softening-point, of
certain kinds of Bohemian and German glass, makes them invaluable in
the laboratory of the chemist. On the other hand, the ready fusibility
of glass containing lead was, as we shall see, one of the causes that
promoted the adoption of such a glass in our furnaces.
Thus we find that the potash-lime glass of Bohemia, containing a high
percentage of silica, excels in hardness and resistance to heat; on the
other hand, the various kinds of glass containing lead are soft and
easily fusible, and at the same time they combine a high specific
gravity with a wide dispersive power. What we may call the maritime or
soda-lime glass takes an intermediate place in all these respects. This
is indeed an additional reason for regarding this great family of
‘Mediterranean’ glass as the normal type.
The two essential elements, then, required by the glass-maker are, in
the first place, silica, and secondly an alkali, in each case as pure
as possible, and in a convenient form for mixing and fusing together. I
do not propose here to do more than indicate the source of these
materials.
The silica has at all times been derived either from solid quartz,
whether in the form of rock crystal or of the white pebbles from the
beds of Alpine rivers, or more often from sand obtained either by
excavation or from the seashore.
In the case of the alkali, the maritime people of the South extracted
their soda, for the most part, from the ashes of certain plants growing
in salt marshes near the sea. Most of these maritime plants belong to
the natural order of the Chenopodiaceæ, the goose-foot or spinach
tribe, and we find among them various species of Salsola, Chenopodium,
Salicornia, etc. These plants were all included in old days under the
vague name of _kali_. The roughly lixiviated ashes exported from Spain
were known in the trade as _barilla_; those from the Levant as
_roquetta_.[4] In other instances the impure alkaline carbonates were
found ready at hand—as in the case of the natron deposits not far from
Cairo. In the North the principal source of soda was till recent days
the _varech_ or kelp, cast up on the west coast of France and of
Scotland.
The inland folk, on the other hand, had to find the alkali for their
glass in the ashes of plants. This ‘potash’ was obtained by lixiviating
the ashes of various trees and bushes—in Germany the ashes of
beechwood, in France those of the bracken or _fougère_, were most in
favour.
The quality of the glass depended in great measure upon the care taken
in the preparation of the soda or potash. But the more impure ashes had
this advantage: the amount of lime, to say nothing of the iron oxide
and alumina, that they contained, rendered unnecessary in many cases
the addition of any further basic material; even the comparatively pure
Spanish barilla contained as much as seven per cent. of lime. In other
cases that base had to be added, generally in the form of a more or
less impure limestone.
Of the furnaces and of the various operations that come into play in
the preparation of the glass I shall treat as the occasion arises in
the following chapters. As, however, in this book we are—at least
after the ‘primitive glass’ has been dealt with in the next
chapter—almost exclusively concerned with vessels of ‘hollow ware’
made by a blowing process, it may be well to indicate, in this
introductory chapter, the nature of this process, and to give the names
of the principal tools used. These implements—apart from quite modern
improvements with which I am not concerned here—are of the simplest
nature, and have undergone little change during the last five hundred
years—perhaps I might say since the days of the Romans.
The molten glass is collected on the extremity of the blowing-iron to
form a ‘gathering.’ This gathering, while still in a soft condition, is
rolled upon the ‘marver’ into a cylindrical mass. By blowing down the
tube this mass is now distended to form a hollow pear-shaped vesicle,
for which it will be convenient to adopt the French term _paraison_. It
is from this paraison that a start is made to form by a ‘spinning’ or
‘flashing’ process a sheet of broad or crown glass; again, the vesicle
may be made to assume a cylindrical shape, and then opened out to form
larger sheets of glass; or finally—and this is for us the most
important—by holding the blowing-iron to which the bulb of glass is
attached in a vertical position (or sometimes by swinging it over the
workman’s head), and then by shaping it by means of certain simple
tools, the paraison is started on the course by which it will finally
be converted into a bottle or into a bowl-shaped vessel. I will here
only dwell on one point. It is evident that so long as the glass is
attached to the blowing-iron, although a simple bulb-shaped vessel may
be formed, there is so far no means of shaping or finishing the upper
portion. Before this can be done the further extremity of the paraison
must be attached by means of a small gathering of molten glass to a
light tapering rod of iron, the ‘punto’ or ‘pontil.’ The vessel—for so
the paraison may now be called—is at this stage removed from the
blowing-iron. This is done by ‘wetting it off’ by means of a rod of
moistened iron. The glass vessel, now attached by its base to the
pontil, is reheated, and the further treatment taken in hand by a
workman seated on a stool with long projecting arms, on which (or on
the knee of the workman) the pontil is rotated. The shaping is chiefly
done by an iron instrument called the ‘procello,’ or spring-tool,
formed like a pair of sugar-tongs by two blades connected by an elastic
bow. Finally, the edges are finished off by shears and scissors of
various forms, which cut the hot glass as if it were a piece of soft
leather. The now finished vessel is removed from the pontil by wetting
the point of attachment, and is taken to the annealing oven.
In this very summary account of the processes involved in making, say,
a flask of simple shape, I have only dwelt upon such instruments and
methods as have for several centuries been in general use.
THE DECAY OF GLASS
Before ending this preliminary chapter, a few words may be said of the
changes that take place in glass in the course of time from the action
of the surrounding medium.[5] These changes are in the main due to the
moisture and carbonic acid contained either in the soil or in the
atmosphere. Perhaps what is most striking in this action is on the one
hand the apparently capricious and irregular way in which the glass is
attacked, and on the other the great beauty of the iridescent effects
that so often accompany the process of decay.
As to the apparent irregularity in the progress of the superficial
decay, it would seem that, apart from differences in the chemical
composition of the glass, much depends upon the preservation of the
original smooth ‘epidermis.’ Once this is impaired, whether by
accidental scratches or by the growth of fungus or lichen, the carbonic
acid or the ammonia salts contained in the air or soil find, in the
presence of moisture, a secure lodgment, and the work of decay proceeds
rapidly. Thus in the case of the little flasks of primitive glass of
which I shall have to speak in the next chapter, in one example it may
be found that the smooth skin of the glass has for more than three
thousand years remained absolutely intact, while in another specimen
from a neighbouring tomb the glass not only on the surface, but far
into the interior, has taken on a talc-like or porcelainous
consistency, and the brilliant colours have for the most part
disappeared.
There is no need to enter into the details of the chemical processes
involved in this process of decay. Suffice to say that the action is
one of the same nature as that which has played so important a part in
the geological changes of the earth’s surface, especially in the
disintegration of the granitic rocks. It depends upon the power
possessed by carbonic acid, in the presence of moisture, of decomposing
the silicates of the alkalis. The soluble carbonate of soda or of
potash thus formed is then quickly washed out from the surface of the
glass. There remains, in the form either of iridescent scales or of an
opaque pearly crust, a layer consisting not perhaps of pure silica, but
of an acid silicate of lime, alumina, or lead as the case may be.
Now a piece of clear glass may appear to the eye to be devoid of
internal structure. But the ‘metal’ has, we know, in every case been
subjected during the manufacture to a complicated series of involutions
and doublings, to say nothing of the subsequent inflation if the glass
has been subjected to a blowing process. When decay sets in—something
similar may at times be seen in the case of a piece of wrought
iron—this complicated formation is in part revealed, for it is evident
that upon it the lines taken by the decay are in a measure dependent.
On blown glass especially, the disintegration of the surface tends to
result in a scaly formation resembling that of the shell of an oyster.
As a result of the decomposition of light in its passage through these
fine superficial films, and of the partial reflection from the back of
the scales at various depths, we get those unsurpassed iridescent
effects that we associate above all with the glass of the Romans. That
these brilliant hues are dependent entirely upon the physical structure
is well shown by the total disappearance of the colours when the
surface of a piece of iridescent glass is moistened, as well as by
their reappearance when the glass is again dried.
Lead of glass is much less liable to such changes, but where in such
glass decay has once set in, the whole mass may be converted into a
white horny substance.
In other cases the surface of a piece of clear white glass will become
gradually filled with a series of minute intersecting fissures, which
in time may penetrate the whole mass. When this change has been fully
developed we get a true crackle-glass, not to be confounded with the
frosted glass of Venice mentioned in Chapter XIII. This fissuring of
the glass-mass in its various stages may be traced in many of the
specimens of Venetian, Netherlandish, and English glass at South
Kensington. When fully developed the effect is at times very beautiful.
The tints of coloured glass may, it would seem, change in the course of
time. Colourless glass also, from which the greenish shades derived
from protoxide of iron have been removed by the addition of binoxide of
manganese, is above all liable to assume in the course of time a purple
tint under the action of sunlight. Again, if sulphur be present in
glass, as is the case where sulphate of soda has been employed as a
source of the alkali, the soda salt may be reduced by any protoxide of
iron that is present. The sulphide of sodium and the sesqui-oxide of
iron thus gradually formed will both of them tend to give a yellowish
tint to the glass.[6]
Changes of this nature may occasionally have come about in the stained
glass of the windows of our Gothic churches—the flesh-tints, which we
know were produced in early days by manganese, may in the course of
time have become of a more pronounced purple hue.