310 



MINERALOGY. 



Next to Iron, Lead is the most extensively dispersed, and 

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

 found pure, but mostiy combined with Iron, Manganese, 

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

 mon purposes is obtained from 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 which it is applied, 

 is the glazing Earthenware ; the Oxyde of Lead is used in 

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

 mony, it forms the types used in printing. 



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



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

 ceedingly sonorous, is harder than Silver ; and 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 

 rarious mineral substances ; it is used as already observed, 

 for alloying Gold and Silver; Copper alloyed with Zinc, 

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

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

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

 Telescopes ; Copper filings, or plates oxydized by acetous 

 acid, forms into green chrystals, which are used in painting, 

 under the name of Verdegrease 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 



