the Analyses of M. Klaprolh. 235 



Arsenical Iron Ore. 

 This ore, which i^ exceedingly rare, is found also at Car- 

 rarac, in the county of CornwaJl. M. Klaproth had only 

 one very small cubical crystal of it, with brilliant and po- 

 lished facets, of a meadow green colour, in a piece of cop- 

 per ore in quartz. 



He does not indicate the proportions of its component 

 parts ; but he analysed a variety of this iron ore crystallized 

 m large cubes of an olivin green colour, extracted from a 

 newly opened pit, and fnund""that it did not contain a single 

 atom of copper. 



Analysis of the Ore of Mimate of Copper. 

 The combination of muriatic acid with copper, an- 

 nounced by Berthollet and Proust, in their analyses of the 

 green sand of Peru or of Acatamit, proves that muriatic;, 

 acid is one of the mineralizing substances of this metal. 



M. Proust has since given an analysis of the green copper 

 ore found at Los-Remollinos, in Chili, which is also com- 

 posed of muriate of copper. 



M. Klaproth repeated this analysis on a very large quan- 

 tity of this fossil, which is still rare. This ore, after being 

 reduced to powder, and freed by washing from the ochre 

 with which its crystalline texture was penetrated, had a 

 beautiful dark green colour. 



Exposed to the blowpipe on charcoal, it communicated to 

 the flame a bright blue and green colour. The muriatic 

 acid is soon volatilized, and there remains on the charcoal 

 a button of pure copper. 



If the ore be heated in a crucible it soon assumes a black 

 colour ; but it gradually becomes greenish in the air. It 

 loses from six to seven per cent, when moderately heated; 

 and from fifteen to eighteen when brought to a red heat. 



Water boiled with a portion of pulverized ore, and then 

 fdtered, passed without any colour ; and a solution of ni- 

 trate of silver produced only a slight white precipitate, 

 which became black in the light. This proves that the 

 muriatic acid was not found in it in that proportion which 

 is ncocssary to be very soluble in water. 



A huncired parts of this ore contain, according to 

 M. Klaprolh, 



Oxide of copper - - - 73 

 Muriatic acid - - - . lO'l 



Water of cjystallizalion • l6-9 



100 



And, 



