288 Elements of Mineralogy. 



of iron may then be diflblved by the marine, 

 and precipitated by the mineral alkali, Of it 

 may be further calcined, and then weighed. 

 The annexed tables fhew the correfpondence 

 betwixt the weight of the calx, or the precipi- 

 tates with that of iron in its metallic ftate. 

 See alfo Chap. 15. N- 18. 



42. To analyfe the 'white calcareous iron 

 cre> it fhould be firft calcined to find the 

 weight of the fixed air and water, then 

 thrown into dephlogifticated nitrous acid, and 

 fhaken for a few minutes until the menftruumt 

 begins to acquire a yellow colour ; it will 

 then contain the calcareous earth only, which 

 may be precipitated by the mineral alkali, 

 and weighed; the refiduum well calcined 

 may be treated with the acetous acid as 

 above. 



43. According to Mr. Rlnman, the con-* 

 tents of this ore may be conjectured very 

 nearly from its fpecific gravity ; for as 80 is 

 to i oo, fo is the fpecific gravity of this ore 

 to its contents per cent. 



44. The pyritous, argillaceous and ftony 

 ores are analyfed by folution in marine acid, 

 to which, if neceffary, a little of the nitrous 

 may be added : this digeftion fhould be 

 continued as long as the menftruum acquires 



a yellow 



