38 Klaproth on the Chemical Analj/sis 



[Klaproth attributes the loss, amounting to 5.52 per cent., to 

 oxygen, and supposes that the bismuth is not contained in the 

 ore entirely in the metallic state.] 



Analysis of the Blue Iron Ore of Eckartsherg. 



This ore occurs in kidney-shaped masses of an indigo-blnc 

 colour ; a tint which it derives from exposure to air, for when 

 recently taken from the strata in which it is found it is nearly 

 white. It is soft and easily friable. 



A. 



a. 100 grains gradually heated red-hot in a small retort lost 

 20 grains, and acquired a brown colour. The loss consisted of 

 pure water. 



b. Exposed in a crucible to a more intense heat, the ore 

 melted into a steel-gray slag, of a metallic lustre, and slightly 

 magnetic. 



B. 



a. 100 grains of the ore were mixed with a solution of caustic 

 soda, and evaporated : the dry mass being softened with water, 

 there remained brown oxide of iron, which was collected, edul- 

 corated, dried, triturated with a little oil, and ignited in a close 

 crucible. It gave 47.50 grains of black oxide of iron. 



b. The alcaline liquor was neutralized with nitric acid, and 

 tested by ammonia, which afforded no precipitate : the ammonia 

 being again supersaturated with nitric acid, acetate of lead was 

 added, which caused a precipitate of phosphate of lead, 

 weighing, after having been washed, dried, and moderately 

 heated, 142 grains, equivalent to 32 grains of phosphoric acid. 



100 parts, therefore, of this reniform blue iron ore, con- 

 sists of 



Black oxide of iron (B a) 47.50 



Phosphoric acid . (B 6) 32 



Water .... (A o) 20 



99.50 



