120 

 GLASS FOR HOUSEHOLD USE AND FANCY PURPOSES. 



BY APSLEY PEL1ATT. 



Before entering upon the consideration of the various descriptions 

 of glassware, it may be convenient to state a few of the distinctive 

 properties of good glass, and the difficulties the manufacturer has to 

 overcome, in order to produce superiority of quality. 



Glass has become of immense importance : it is technically termed 

 metal, and is conducive, from its many and important qualities, alike to 

 the comfort and convenience of man, and to the elevation of his mental 

 powers. To the property of translucency, &c, possessed by glass, man is 

 indebted for his knowledge of the most exalted as well as -the most 

 minute of the great Creator's works ; other properties of glass, its 

 power of resisting acids, and its non-conduction of the electric fluid, 

 constitute it a material of great value and importance. Glass is 

 materially divided into two specific classes — simple and compound. 



Simple glass is that in which only silica and flux are the con- 

 stituents, the flux being either soda, potash, lime, magnesia, alumina, 

 or mixtures of some of them, in which case the glass is simply a 

 silicate of an alkali. Of such is plate, window, and bottle glass of 

 every description ; the difference of quality depending entirely upon 

 the character of the materials. 



Compound glass* is that in which, besides silica and alkali, 

 the oxide of a metal is also a component part. This glass is called 

 in England, flint glass, and on the Continent crystal, and from it, in 

 England, are made all articles of luxury and domestic use. The 

 object of introducing a metallic oxide into glass is to add to its 

 density (an object of great importance for achromatic purposes), whereby 

 greater brilliancy is obtained, the rays of light not being allowed to 

 pass so straightly through, as in the simple glasses, but being more 

 refracted or broken (so to speak), as they pass through. This quality 

 is further taken advantage of by the glass cutter, who aims to produce 

 such patterns upon the objects he manufactures, as further tend to break 

 the rays of light. Flint glass being usually employed for the manufac- 

 ture of articles of luxury, quality is of immense consequence, as but a 

 very trifling inferiority in any of its properties renders it of compara- 

 tively little commercial value ; whereas, the price is looked upon as a 

 secondary object, if the quality is decidedly superior. The manufac- 



* 'Traite sur l'Art de Vitrification et des Verres Colores,' &c. — D'Aude- 

 nart, Paris, 1825. ' Cyclopedia of Useful Arts and Manufactures,' hy Tom- 

 linson, under the head Glass.— G. Virtue. Lardner's ' Cyclopaedia,' Porcelain 

 and Glass Manufacture. — Longman and Co. Pellatt's 'Curiosities of Glass 

 Making.'— Bogue, Fleet Street. 



