Ohap. 67.J OESIAX GLASS. 381 



Such was the ancient method of making glass : but, at tlie 

 present day, there is found a veiy white sand for the purpose, 

 at the mouth of the river Yolturuus, in Italy. It spreads 

 over an extent of six miles, upon the sea-shore that lies 

 between Cumse and Liternum, and is prepared for use by 

 pounding it with a pestle and mortar; which done, it is mixed 

 with three parts of nitre, either by weight or measure, and, 

 when fused, is transferred to another furnace. Here it forms 

 a mass of what is called ''hammonitrum;" which is again 

 submitted to fusion, and becomes a mass of pure, white, glass. 

 Indeed, at the present day, throughout the Gallic and Spanish 

 provinces even, we find sand subjected to a similar process. 

 In the reign of Tiberius, it is said, a combination was devised 

 which produced a flexible^^ glass ; but the manufactory of the 

 artist was totally destroyed, we are told, in order to prevent the 

 value of copper, silver, and gold, from becoming depreciated.^' 

 This story, however, was, for a long time, more widely spread 

 than well authenticated. But be it as it may, it is of little 

 consequence ; for, in the time of the Emperor Nero, there was a 

 process discovered, by which two small glass cups were made, 

 of the kind called " petroti,"^^ the price of which was no less 

 than six thousand sesterces ! 



CHAP 67. OBSIAN GLASS AND OBSIAN STONE. 



Among the various kinds of glass, we may also reckon 

 Obsian glass, a substance very similar to the stone^^ which 

 Obsius discovered in ^^thiopia. This stone is of a very dark 

 colour, and sometimes transparent; but it is dull to the sight, 

 and reflects, when attached as a mirror to walls, the shadow 

 of the object rather than the image. Many persons use it^ 



glass, resembling obsidian stone." — Hist. Inv. Vol. II. pp. 69, 70. JBohn's 

 Edition. 



^^ Knowles says, in his Turkish History, p. 1273, that in 1610, among 

 other rare presents sent to the King of Spain from the Sophy of Persia, 

 there were six drinking- glasses, made of malleable glass so exquisitely 

 tempered that they could not be liroken. 



^' Lion Cassius and Suetonius tell a similar story ; and, according to one 

 account, Tiberius ordered the artist to be put to death. 



^^ This reading is doubtful. It would appear to mean " stone handled.'' 

 Another reading is " pterotos," " Avith winged handles." 

 • 63 Volcanic glass, feldspar in a more or less pure state, our Obsidian, is 

 probably meant ; a word derived from the old reading, Obsidius, corrected 

 Dy Sillig to Obsius. 



90 He is speaking of the stone, not the glass that resembled it. 



