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• ON THE CONSTRUCTION OF FURNACES, ETC.
Stability of Furnace essential. - Fritting Furnace, or Calcar. — Its Use. -
Working Furnace. - Double Furnace. - Proportionate Dimensions of
Furnace and Pots. - Wood Furnaces. - Comparative Consumption of
· Fuel in Wood and Coal Furnaces. - Annealing Oven. - Lier Pans. -
Glass Pots. Their Formation and Seasoning.
- Page 152
ON THE MANUFACTURE OF FLINT GLASS.
The most beautiful and costly Kind of Glass. - Importance of its Quality
for Optical Purposes. - Experiments for its Improvement. - Undertaken
by the Royal Society. - Promoted by Government. - Distinguishing
Properties of Flint Glass. – To what owing. Different Compositions.
Process of Melting. -Glass-gall. - Its Use. Curious Phenomenon. -
Implements. - Collecting Glass on Rod. — Marver. - Paraison. - Blow.
ing.- Re-heating.- Elongating. - Pontil. - Fashioning.- Detaching. -
Removal to Annealing Oven. - Moulding. - Annealing. - Why indis-
pensable. - Bologna phials. — Rupert's Drops.
ON THE MANUFACTURE OF CROWN GLASS, BROAD GLASS, AND
Description of Crown Glass. Harder than Flint Glass. - More difficult to
fashion. - Its Composition. - In France. - In England. - Fritting. -
Cullet. - Refining. - Sulphate of Soda. – Vegetable Charcoal. - Gather-
ing. - Blowing. - Re-heating. - Flattening. - Transferring to Pontil.
Twirling. - Expanding. - Opening. - Annealing. - Nice Regulation of
Temperature required in this Process. - Qualities of Crown Glass,
German Glass. -Broad Glass. Inferior to Crown Glass. - Its Compo-
sition. - Preparation. -Working. - Bursting. - Opening. - Annealing.
- Bottle Glass. - Manufacture checked by Increase of Duty. — Com.
position. - Restrictions as to Materials. - Their bad Tendency. - Supe-
riority of Bottle Glass for certain Purposes. - Materials employed in
France. - At Newcastle. — Fashioning. — Moulding.- Experiments sug-
gested by Count Chaptal. - Klingstein.-Volcanic Granite.
ON THE MANUFACTURE OF PLATE GLASS.
Different Descriptions of Plate Glass. — Blown Plates limited in Size. -
Cast Plate Works at Ravenhead. - Difficulties of the Process. - Mate.
rials. - Various Compositions. Borax, Mixing Materials, -Fritting
- Furnaces and Crucibles at St. Gobain. - Pots. - Cuvettes. – Regula-
tion of Firing. - Casting Tables.- Arrangements of Foundery at Raven-
head. - Annealing Ovens. — Process of casting Plates. - Annealing. -
Squaring. – Grinding. — Economical Improvement. - Smoothing. -
Emery Powder. - Comparative Value of large and small Plates. - Polish-
ing. - Silvering. - Preparation of Amalgam. — Mode of its Application.
- Blowing Plate Glass. — Punching. - Partial Cutting. - Transfer to
Pontil. — Completion of cutting. - Opening. - Annealing. - Sizes of
Plates. — Effect of Sun's Rays in discolouring Plate Glass. - Page 195
ON THE COMPOSITION OF ARTIFICIAL GEMS.
Great Interest formerly attached to this Subject. — Different Compositions
for artificial Gems. — Mode of Preparation. - Rock Crystal formerly em-
ployed.-Not superior to Sand. — Diamond Pastes. -Selection of various
Pastes for imitating different Gems. -- Reasons for such Selection. 217
ON THE MANUFACTURE OF GLASS FROM CALCINED BONES.
Preparation of Bones. Their Vitrification. - Process known to Becher. ---
Concealed by him. — Curious Suggestion as to its Employment. - This
Glass highly electric when newly made. . .
ON THE USE MADE OF THE BLOW-PIPE, AND ON VARIOUS SMALL
MANUFACTURES OF GLASS
Thermometer Tubes. - Manner of giving to them an elliptical Bore.
Blowpipe and Apparatus described. - Materials used. -- Method of work-
ing. - Sealing Tubes. - Bending and joining Tubes. - Bulbs. - Spun
Glass. Watch Glasses, - Lunette Glasses. - Glass Beads - Manufactory
at Murano. - Striped Tubes. - Mode of forming Beads. - Sorting them.
.-Numerous Kinds of Beads.- Mock Pearls.- Manner of their In-
vention. - And Formation. - Dial Plates. - How formed. -Lettering
and Figuring. • • • • • • •
ON THE FORMATION OF LENSES.
Preparation of the necessary Tools.-Choice of Glass. — Grinding. - Po.
lishing. - Curdled Lenses. -- Means used for avoiding this Defect. 242
ON THE PRINCIPAL DEFECTS OBSERVABLE IN GLASS.
Striæ. Render Glass unfit for Optical Purposes. — Threads.- Render
Glass fragile. Cause of this. -Tears. - One of the greatest defects.
- Render Glass useless. — Knots. - Bubbles. - Whence they proceed. -
Do not much affect the Quality of Glass. -Objects to be attained for
avoiding these Defects. — M. Guinand. - His humble Origin. - Energy of
Character. - Examines Telescopes and constructs others. — Unable to
procure Glass of good Quality. - Is incited to examine into the Causes
of Inferiority. - His extraordinary Perseverance amidst Accidents and
Difficulties. - His ultimate Success. — Accident leading to further Im-
provement. — Prosecutes his Art in Bavaria. — Returns to Switzerland,
and further pursues his favourite Object. - Dies. — Frauenhofer. -
Rises from Obscurity by his Talents. — His scientific Acquirements. -
Produces Specimens of perfect Glass. - Dies at an early Age. Respect
paid to his Memory.
ON THE SPECIFIC GRAVITY OF GLASS.
Importance of this Quality. — Experiments of Loysel. - His Reasoning and
Formulæ. - Specific Weight augmented by Lime. -Mixed Glasses,
heir specific Weight. - Method of determining this. Influence of Tem-
perature on the specific Weight of Glass.
ON THE ART OF COLOURING GLASS.
Antiquity of this Art, -Specimens of Roman Mosaic. - Analysis of these
by Klaproth. - Metallic Oxides. - Gold Purple. - Its great colouring
Power.- Kunckel. His Proficiency in colouring Glass. Yellow Colour
- From Silver. - From Lead. — From Tartar.- From Beech Wood
Charcoal. - From Oxide of Iron.-Green. -- Black Glass. — Blue.- Di.
rections found in old Authors.- Imitation of the Garnet. Of the
Amethyst. Of the Emerald. Of Sapphires. -Opaque Glasses.
- Black - White. -Opal. - Ancient Pictures formed of coloured Glass.
-How executed. Description of Ancient Mosaics. - More recent Pro-
secution of this Art - Accidental colouring of Plate Glass at St. Gobain.
Ineffectual Attempts to reproduce this Effect.
ON THE ART OF STAINING AND PAINTING GLASS.
This Art more recent than that of colouring. - Encouraged by the Monks.
- Early Specimen at St. Denis. - Art never much cultivated in England.
-Splendid Paintings at Gouda. - Directions given by old Authors for
composing Colours.-Fluxes. - Vehicles for diluting Colours. -De-
scription of various Stains. - Method of floating these. — Of painting on
Glass. - Imitation of Ground Glass with transparent Patterns. — De-
scription of Kiln employed. — Method of Firing. - Second and third
Firing. - Ancient Method of fixing different coloured Glasses on each
- - - Page 289
ON THE ABT OF CUTTING, ENGRAVING, AND ETCHING ON GLASS.
Origin of the Art of cutting Glass. - Implements. — Manner of their Em.
ployment. Frosting. - Patterns produced by Moulding. — Engraving
on Glass. - Executed with the Diamond. - Etching. -Schwanhard. -
Difference of his Practice from that now used. --Method of Etching. -
Fluoric Acid. - Glass Incrustations, Origin of the Art. - Improve-
- - - - • 305
ON THE DEVITRIFICATION OF GLASS.
First observed by Neumann. - Experiments of Reaumur. — Substance
known as Reaumur's Porcelain. Inappropriateness of this Name,
Uses to which the Substance may be applied. Common Bottle Glass
most proper for this Conversion. - Method of effecting the Change, -
Produced solely by Heat. — Experiment of Dr. Lewis. - Revitrification,
Experiments of Sir James Hall. - Proposal suggested thereby. - Observ.
ations of Guyton-Morveau. -Artificial Intaglios. - Mock Onyxes. —
Power of devitrified Glass to bear sudden Changes of Temperature. - Ex-
periments with coloured Glass.-Glass devitrified by burning Lava. - The
process promoted by multiplying the Ingredients of Glass. - Devitrified
Glass conducts Heat more perfectly than when vitreous. - Becomes a
Conductor of Electricity. - Retains this Property when revitrified. 317