SIO MINERALOGY. 



Next to Iron, Lead is the most extensive!}' dispersed, and 

 is one of the most abundant of Metals; it iias never been 

 found pure, but mostly combined with Iron, Manganese, 

 Antimony, Silver, or their Ores. The Lead used for com- 

 mon purposes is obtained ire m an Ore called Galena, or 

 Sulphuret of Lead, which is composed of Lead, Sulphur, 

 Oxyde of Iron, and Silver, and sometimes it contains Lime 

 and Silex. Among the various uses to vvhi. h it is applied, 

 is the g.azing Earthenware ; the Oxyde ot Lead is used in 

 making Glass; and combined with one fifth part of Anti- 

 mony, it forms the types used in printing. 



6. CorPER. When pure, Copper is about eight times hea- 



TJer than water ; its colour is a yellowish red ; it is ex- 

 ceedingly sonorous, is harder than Silver ; ::nd in 

 respect to fusibility is between Gold and Iron. 



Copper in point of usefulness yields only to Iron, it is 

 widely dispersed, being found pure, and also combined with 

 various mineral substances ; it is used as already observed, 

 for alloying Gold and Silver; Copper alloyed with Zinc, 

 forms Brass, Pinch-Beck, and Tiiisel ; with a small propor- 

 tion of Tin it forms Bell-Metal ; two-thirds of Copper and 

 one of Tin, are used in forming the speculums in rellecting 

 Telescopes ; Copper filings, or plates oxydized by acetous 

 acid, forms into green chrysfals, which are used iii painting, 

 under the name of Verdcgrease or Verdigris. 



7. Tin. This Metal has never been found pure, being 



generally combined with Copper, Sulphur, Iron, &c. 

 it is about seven times heavier than water. Tin is the 



