cf the Ancients rejpe^ing Glafs. 107 



came to be uled along with the fofTil alkali, 

 from an idea of its not only containing iron, but 

 glafs in a liquid form Clear pebbles, lliells, and 

 foflil fand, were alfo in many places employed 

 for the fame purpofe. It is faid, that in India, 

 pieces of native chryftal were ufcd for that pur- 

 pofe ; and on that account, the Indian glafs was 

 preferred to any other; He adds, that light and 

 dry woods were ufed for the melting of glafs; to 

 which they added copper from the ifland of Cy- 

 prus, and the foflil alkali, efpecially that which is 

 brought from the Eafl: Indies. The furnaces are 

 kept burning without intermifTion, that the cop- 

 per may be melted with the glafs, and outf'Sf 

 this compound are made maffes of a coarfe 

 blackifh colour. Thefe lumps or maflfes are 

 again melted, and tinged of the colour required. 

 Some of thefe pieces are brought to the (hape 

 defired, by blowing it with the breath : fom^e are 

 ground in a lathe, and others are emboiTed in 

 the fame manner wiih filver. Sidon was for- 

 merly famous for thefe manufadgres, as fpecula 

 or looking glafles were firfb invented there. The 

 above is defcribed by Pliny, as the ancient me- 

 thod of making glafs. In his time, ic was made 

 with fand found at the mouth of the river Vultur- 

 nus, upon the fliore, for fix miles between Cums 

 and the Lucrine Bay. This fand was very fine, and 

 was ground to powder with a ball or fphere, and 



a mill 



