GLASS 669 



furred to an iron pan suspended over a moderate fire, and continually stirred about 

 as before, whereby the cylindrical bits assume a smooth rounded form ; so that 

 when removed from the fire and cleared out in the bore, they constitute beads, 

 which are packed in casks, and exported in prodigious quantities to almost every 

 country. 



The manufacture of reticulated glass, for which Venice was equally celebrated, was 

 long lost ; it was at length revived by Pohl, and the crackle-glass was in like manner 

 reproduced by the late Mr. Apsley Pellatt in 1851. 



The reticulated glass is produced by a kind of network, consisting of small bubbles 

 of air inclosed within the mass, and ranged in regular series crossing and interlacing 

 each other. To produce this ornamental appearance, hollow glass cones or conical 

 tube are kept prepared, containing already this network-arrangement of air-bubbles. 

 These tubes are made by arranging a number of small glass rods round a centre so as 

 to form a cylinder, and fixing them in this position by melted glass. The cylinder is 

 then heated until the single rods stick together, when they are drawn out on the pipe 

 to a long cone, and spirally twisted at the same time, the one half to the right and 

 the other to the left, when one of these hollow cones is inserted into the other, and the 

 two are heated until they fuse together ; wherever the little rods cross each other 

 a bubble of air will be inclosed, and this occurring in a very regular manner, the 

 reticulated appearance is produced. 



The Venetians were also celebrated for their filigree. This glass has of late 

 years been re-introduced in France and in this country. The process of manu- 

 facture has been thus described by Mr. Apsley Pellatt, in his Curiosities of Glass 

 Manufacture : 



'Before ornaments or vessels can be blown, small filigree-canes, with white or 

 variously-coloured enamels must be drawn. These are first " whetted " off to the 

 required lengths, and then put into a cylindrical mould with suitable internal 

 recesses, and both cane and mould are thus submitted to a moderate heat. The 

 selection of the colour of the canes depends upon the taste of the manufacturer ; 

 two to fcnir white enamel-canes are chiefly used, alternately, with about half the 

 number coloured. The blower then prepares a solid ball of transparent flint-glass, 

 which being deposited in contact with the various canes, at a welding heat, occasions 

 them to adhere. This solid ball is then taken from the mould, is re-heated, and 

 " marvered " till the adhering projecting ornamental canes are rubbed into one 

 uniform mass ; the ball is next covered with a gathering of white glass, which must 

 then be drawn to any size and length that may be required. Should a spiral cane 

 be preferred, the " pucellas " holds the apex in a fixed position, while the ornamental 

 mass, still adhering to the glass-maker's iron, is revolved during the process, till 

 the requisite twist is given. Where vases are formed of alternately coloured and 

 enamelled filigree-canes, the above process is repeated, and the usual mode of blowing 

 is followed.' 



The Venetian ball is a collection of waste pieces of filigree-glass conglomerated 

 together without regular design : this is packed into a pocket of transparent glass, 

 which is adhesively collapsed upon the interior mass by sucking up, producing out- 

 ward pressure of the atmosphere. 



MUlefiore, or star- work of the Venetians, is similar to the last, only, the lozenges of 

 glass are more regularly placed. 



The Vitro di Trino of the Venetians is similar to the filigree in many respects ; but 

 by closing an outer on the inner case, each containing filigree-canes, a bubble of air 

 is inclosed between each crossing of the canes. 



The celebrated frosted glass of the Venetians was re-introduced by Mr. Apsley 

 Pellatt in 1851, who thus describes the process of manufacture : 



'Frosted glass, like Vitro de Trino, is one of the few specimens of Venetian work 

 not previously made by the Egyptians and the Eomans ; and not since executed by 

 the Bohemian or French glass-makers. The process of making it, until recently 

 practised at the Falcon Glass "Works, was considered a lost art. Frosted glass has 

 irregularly- varied marble-like projecting dislocations in its intervening fissures. 

 Suddenly plunging hot glass into cold water produces crystalline .convex fractures, 

 with a polished exterior, like Derbyshire spar; but the concave intervening figures 

 are caused, first by chilling, and then reheating at the furnace, and simultaneously 

 expanding the reheated ball of glass by blowing ; thus separating the crystals froiii 

 each other, and leaving open figures between, which is done preparatory to forming 

 vases or ornaments. Although frosted glass appears covered with fractures, it is 

 perfectly sonorous.' 



Glass, its physical condition and chemical constitution. So far as may be inferred, 

 from the analysis of ordinary commercial samples of window-glass, this substance 

 has not only a very variable composition, but, worse than this, it is out of all keeping 



