HISTORY OP CALIFORNIA. 



241 



silver occasionally found in Siberia, and known under 

 the name of electrum. Its color is pale brass-yellow, 

 passing into silver-white. It occurs in small plates 

 and imperfect cubes, and possesses many of the charac 

 ters of gold, but it consists only of 64 per cent, of that 

 metal, and 36 per cent, silver. It is at once known 

 by its low specific gravity, which does not exceed 12. 



Other mixtures of gold are (1) a rJwdium-gold 

 found in Mexico, and containing 34 to 43 per cent, of 

 rhodium, having a specific gravity of 15J 16-8, and 

 a clear, dirty yellow color ; and (2) a palladium-gold 

 (containing 9.85 per cent, palladium, and 4*17 per 

 cent, silver) found in Brazil and elsewhere in South 

 America, in small crystalline grains of pale yellow 

 color. The auriferous ores of tellurium, including 

 silver, have hitherto only been found in Transylvania. 

 Their color is steel-gray, and they tarnish on exposure- 

 The variety called graphic-gold, or graphic tellurium, 

 consists of about 60 per cent, of tellurium, 30 per cent, 

 gold, and 10 per cent, silver, and is worked chiefly 

 as an ore of gold. Another variety, "yellow gold 

 glance," yields somewhat less tellurium, gold and 

 silver, and as much as 20 per cent, of lead. 



Having now explained at some length the more 

 manifest characteristics of gold, namely, its color, 

 hardness, and specific gravity, it is necessary, before 

 explaining the mode of separating it from associated 

 minerals, that we should here give some account of 

 the behavior of this metal under the blowpipe, and 

 when exposed to simple cheinicaj tests. The assay 

 of gold and its accurate analysis, we postpone for the 

 present. 



The method of blowpipe analysis, although exceed 

 ingly useful, is not absolutely necessary in the case 

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