isa-normaladvance-1913-00085-Jan

Description:	The^ Indianastate normalLibraryal AdvanceVolume XVIII.TERRE HAUTE, IND., JANUARY, 1913.Number 4.Coloration of <§las&HELEN LOUISE GILLUMTHE art of coloring glass, contrary to the found, through exhaustive experiments, threebelief of many people, goes back beyond different formulas which produce it. Each ofany records which now7 exist of the earliest these contain different things, but he agreeshistory of the world. In Egypt, in the tombs that in all of them the final step is the same,and ruined temples, articles made of colored AArhen the glass is liquid, thirty-eight perglass have been found, which date back more cent of cast iron filings, rolled up in paper, isthan three thousand years before the time of thrown into the pot, and the mixture is stirredChrist. Many of these are imitations of pre- with a red-hot iron. The glass becomes blood-cious stones, and are of wonderful color and red, opaque, and full of small bubbles thetransparency. Also, pictures have been found draught of the furnace is stopped, the pot iswhich depicted the manufacture and blowing covered with a lid, ashes are heaped over it,of glass in Egypt as early as 3500 B. C. The and it is allowed to cool very slowly. NextPhoneicians, too, practiced the art of glass- day, on breaking the crucible, Aventurine ismaking and coloring. For many centuries this found to have been produced.art was confined to Egypt and the East, but Colored glass is produced by adding to onegradually it was introduced into Italy, and or another of the many varieties of soda-lime,worked its way northward. For many years potash-lime, or potash-lead glasses, some me-Aenice held the secrets of the finest colored tallic or non-metallic oxide or oxides, or evenglass, and even now, the glass makers of some substance of organic origin. These last,Murano make one kind of glass which no one however, are few in number. AA7hen choosingelse can make. It is the Aventurine glass, and the foundation glass, care must be taken tois an imitation of a natural glass that is found choose a glass that is essentially the same asin Spain and Norway. However, this glass the white glass with w7hich the colored glasshas been carefully studied, and Peligot gives is usually united in working it into usefulits analysis as follows: articles. Many glasses, which we believe areSilica 67.7% colored, have only a thin film of colored glasspotash 5.5% over a clear white glass, because if the col-Lime . 8.9% ored glass is even a small fraction of an inchSoda 7.1% thick, it becomes opaque and even changesOxide of tin 2.3% color. So, when the white glass and coloredOxide of lead 1.1% glass are w7orked together, they must be es-Metallic copper 3.9% sentially the same, or they would crack and.Oxide of iron 3.5% break on account of the difference in coefficientThis formula, when used, gives a glass of expansion by heat,similar to the Venetian Aventurine, but not I shall discuss the coloration of the glassexactly like it. There have been other men by colors, rather than by the substances whichalso, who have attempted to produce this rare produce the colors. Frequently, the same ele-glass, and have arrived at different formulas ment will produce several different colors,from that of Peligo. Hautefenille alone has when treated in different ways.
Source:	http://indstate.contentdm.oclc.org/cdm/ref/collection/isuarchive/id/34530
Collection:	Indiana State University Archives

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