Chap. 47.] THE ORES OF LKAD. 213 



the stream of water whicli is passed through them detacliing 

 certain black pebbles, mottled with small white spots and of 

 the same weight^" as gold. Hence it is that they remain with 

 the gold in the baskets in which it is collected ; and being 

 separated in the furnace, are then melted, and become con- 

 verted into white lead.^^ 



Black lead is not procured in Gallsecia, although it is so 

 greatly abundant in the neighbouring province of Cantabria ; 

 nor is silver procured from white lead, although it is from 

 black.^2 Pieces of black lead cannot be soldered without the 

 intervention of white lead, nor can this be done without em- 

 ploying oil;^^ nor can white lead, on the other hand, be united 

 without the aid of black lead. White lead was held in esti- 

 mation in the days even of the Trojan War, a fact that is at- 

 tested by Homer, who calls it '' cassiteros."^* There are two 

 different sources of black lead : it being procured either from 

 its own native ore, where it is produced without the intermix- 

 ture of any other substance, or else from an ore which con- 

 tains it in common with silver, the two metals being fused to- 

 gether. The metal which first becomes liquid in the furnace, 

 is called " stannum ;"^* the next that melts is silver ; and the 

 metal that remains behind is galena,^^* the third constituent 

 part of the mineral. On this last being again submitted to 

 fusion black lead is produced, with a deduction of two-ninths. 



90 Tin ore is among the heaviest of minerals, though the specific gravity 

 of the metal is small. M. Haefer is of opinion that these pebbles con- 

 tained platinum. 



91 Or tin. The greater fusibihty of the tin producing this separation. 

 — B. 



9- We may conclude that the '"plumbum nigrum," or "black lead" of 

 Pliny is the Galena or sulphuret of lead of the moderns ; it is frequently 

 what is termed argentiferous, i. e. united with an ®re of silver, and this in 

 such quantity as to cause it to be worked for the purpose of procuring the 

 silver. — B. See Beckmann, Vol. II. p. 210. 



93 *< Instead of oil, workmen use at present ' colophonium,' or some 

 other resin."— Beckmann, Vol. II. p. 223. See also B. xxxiii. c. 20. • 



91 Iliad, xi. 25, and xxiii. 561.— B. 



95 Ajasson considers this to be Bismuth; but it is more probable that 

 Beckmann is right in bis conclusion, supported by Agricola, Entzel, 

 Fallopius, Savot, Bernia, and Jung, that it was a compound metal, the 

 Werk of the German smelting- houses : a metal not much unhke our 

 pewter, probably. See Beckmann, Hist. Inv. Vol. II. pp. 209, 212, 224. 

 Bohn's Edition. 



9^* See B. xxxiii. c. 31, and c. 53 of this Book. 



