COLOURED GLASSES OF THE ANCIENTS* 



Though Pauw and fonle other antiquaries are more incrmed 



to afcribe this difcovery to the Egyptians, who arefaid to have 



Glafs-houfes at conftrufted the firft glafs-houfe, in the remoteft ages, at Diof- 



moKmote^''*' polis, the ancient capital of Thebais ; yet it likewife appears, 



ages, from (he writings of the ancients, that this art muft have ar- - 



rived at a confiderable degree of perfe6tion, chiefly among the 

 and among the Phenicians; as alfo, in general, this nation feems, in her flou- 

 fhenicians. rifliing age, to have been almoft in the exclufive poiTeflTion of 

 manufadures. Sidon, that colony of theirs fo flourithing by- 

 commerce, arts, and manufaftures, was not lefs famous on ac- 

 count of her glafs-houfes. Thefe, according to the teftimony 

 of Pliny, obtained for fome hundred years the chief ingredients 

 of their glafs from the fea-ftiore near the Phenician town Acco, 

 afterwards called Ptolemais, and now St. John d'Acre, in the 

 vicinity of the fmali river Belus, which there empties itfelf into 

 the Mediterranean. 

 The nltrum or The fubftance which the ancients employed for the purpofc 

 ancients was ^^ vitrifying the fand, is comprehended by the early authors un-* 

 <6da i der the name of nitrwn; but it has long been generally agreed, 



that they did not mean by it our nitrate of potafli, but the mine- 

 ral alkali or lloda ; confcquenlly their nitraria were not nitre- 

 works, but, flridtly fpeaking, refineries of foda. And from 

 the defcriptions which Pliny and others have given of their 

 nalrum and its properties, it is rendered probable, that in thofe . 

 or rather it con- times all faline fubftances, whether efflorefcing upon the foil or 

 fifted of any fait jgjj j^y ^x'led lakes, if not belonging to the muriatic genus, were 



left upon the r , , tt . , „ , r r ^ 



groMnd (not conudered as natrum. Hence undoubtedly, among thole lalts 

 muriatic) J often occurred real nitre as well as native fulphate of foda.^ 

 This impure fait However, fuch confufion in their ufe in manufafturing glafs 

 was not detri- j^^^ j^yj produced any real detriment ; fince the longer time 

 giafs. during which the ancients expofed their materials for glafs to 



the action of the fire, has been more than fufficient to decom- 

 pofe thofe neutral falts, and to expel from them their acid con- 

 llituent parts. 

 The art of co- The art of colouring glafs feems to be of nearly the fame an- 

 louring glafs is tiquity as the invention of making it j as is evident not only from 

 fame antiquity as feveral paffages in the ancient writers, but may alfo be proved by 

 glafs itfel# adual documents, and, among others, by the varioufly coloured 

 glafs-corals, with which feveral of the preferved Egyptian mum- 

 mies are decorated. This art fuppofes the polTeflion of fome.che- 

 mical knowledge of the metallic oxides, becaufe thefe are the 



only 



