644 GLASS 



Ginger-beer powders are thus prepared : 



White sugar 6 ounces. 



Tartaric acid 1J ounce. 



Carbonate of soda . . . . . 1J ounce. 



Powdered Jamaica ginger .... 2 drachms. 



Essence of lemon 10 drops. 



All the materials are to be carefully dried, and mixed while yet warm, in a warm 

 mortar, and immediately bottled. 



If the acid and the carbonate of soda are kept separate, these precautions are not 

 necessary. 



GINNING is the name of the operation by which the filaments of cotton are 

 separated from the seeds. See COTTON MANUFACTURE. 



GINSENG. The root of the Panax Schinscng, a plant belonging to the Araliacca, 

 or ivy-order. This is highly esteemed as a medicine by the Chinese, who are said to 

 value it at its weight in gold. The American Ginseng is the root of a closely-related 

 plant P. quinqucfolium. 



GXRASOL. The name given by the French to fire-opal. See OPAL. 



GLAXRE. The white-of-egg. This consists, according to Gmolin, of albumen 1 2'0, 

 mucus 2 - 7, salts 0'3, water 85'0. Glaire or albumen (ovalbumcn), is distinguished from 

 the albumen of the serum of the blood (scr albumen), by its being coagulated by ether. 

 Glairo is used by bookbinders in finishing the backs of books, and for a few other 

 purposes in the arts. See ALBUMEN. 



GLANCE. Any minerals exhibiting a brilliant lustre especially of a motalb'c 

 character were so called, the term signifying splendour. Lead-glance, iron-glance, and 

 the like are examples. 



GLANCE-COAL, a name given to anthracite, of which there are two varieties, 

 the slaty and the conchoidal. See ANTHRACITE and COAL. 



GLANCE-COBALT. See COBALT. 



GLANCE-COPPER. See COPPER. 



GLASERZTE. Native sulphate of potash, from Vesuvius. 



GXi ASS ( Verrc, Fr. ; Glas, Ger.) is a transparent solid formed by the fusion of 

 siliceous and alkaline matter. It was known to the Phoenicians, and constituted for 

 a long time an exclusive manufacture of that people, in consequence of its ingredi- 

 ents natron, sand, and fuel abounding upon their coasts. It is certain that the 

 ancient Egyptians were acquainted with glass, for, although we find no mention of it 

 in the writings of Moses, we discover glass ornaments in tombs which are as old as 

 the days of Moses. According to Pliny and Strabo, the glass works of Si don and 

 Alexandria were famous in their times, and produced beautiful articles, which were 

 cut, engraved, gilt, and stained of the most brilliant colours, in imitation of precious 

 stones. The Komans employed glass for various purposes; and have left speci- . 

 mens in Herculaneum of window-glass, which must have been blown by methods 

 analogous to the modern. The Phoenician processes seemed to have been learned by 

 the Crusaders, and transferred to Venice in the 13th century, where they were long 

 held secret, and formed a lucrative commercial monopoly. Soon after the middle 

 of the seventeenth century Colbert enriched France with the blown mirror-glass 

 manufacture. 



Chance may have had a share in the invention of this curious fabrication, but there 

 were circumstances in the most ancient arts likely to lead to it ; such as the fusing 

 and vitrifying heats required for the formation of pottery, and for the extraction of 

 metals from their ores. Pliny ascribes the origin of glass to the following accident : 

 A merchant-ship laden with natron being driven upon the coast at the mouth of the 

 river Belus, in tempestuous weather, the crew were compelled to cook their victuals 

 ashore, and having placed lumps of the natron upon the sand, as supports to the 

 ke ties, found to their surprise masses of transparent stone among the cinders. The 

 sand of this small stream of Galileo, which runs from the foot of Mount Carmol, was 

 in consequence supposed to possess a peculiar virtue for making glass, and continued 

 for ages to be sought after and exported to distant countries for this purpose. There 

 exists good evidence that the manufacture of glass and of vitreous glazes is much 

 older than the time ascribed by Pliny. 



Agricola, the oldest author who has written technically upon glass, describes fur- 

 naces and processes closely resembling those employed at the present day. Neri, 

 Kunckel, Henckel, Pott, Achard, and sonio other chemists, have since then con 

 tr.-.itisos upon the subject; but Ncri, Bosc, Antic, Loysel, and Allut, in the Ency- 

 clopedic Mcthodiquc, arc the best of the older authorities. 



The Venetians wore the first in modern times who attained to any degree of ex- 



