dnalysis of the Copper Ore of Franconiu. 255 



analysis of the Franconia ore, which was made about three 

 years ago. 



The ore occurs in a vein of quartz traversing the mica 

 slate, which forms the mountains of Franconia, a part of the 

 group of the While Hills ; it presents the usual characters of 

 lustre, colour, tarnish, &c. of pyritous copper, and it is asso- 

 ciated with the sulphuret of iron of mineralogists, from which 

 it can be separated by mechanical means. Arsenical cobalt* 

 js found imbedded in the mica slate, and the rock itself pre- 

 sents a distinct blush of peach blossom colour. 



The specific gravity of the ore, from two specimens, was in 

 one 4.039, the other 4.040. The presence of iron, copper, 

 and sulphur, having been detected in this ore by preliminary 

 experiments, a portion was selected as being pure and appa- 

 rently unmixed with sulphuiet of iron, and analyzed in the 

 following manner. 



(A.) Fifty grains in fine powder were digested in dilute 

 nitric acid ; the green coloured solution thus obtained was 

 decanted, and a few drops of muriatic acid were added to the 

 insoluble residue ; the solutions were mingled, and the inso- 

 luble residue was well washed. 



(B.) To the solution thus obtained, after concentration, 

 aqueous ammonia in excess was added; the whole was thrown 

 on a filter, and the precipitate thoroughly edulcorated, dried 

 and weighed ; it was oxide of iron equivalent to 14.09 of 

 metal. 



(C.) The ammoniacal solution was heated with pure potash 

 water, and the precipitate obtained was washed and dried ; it 



* i^illiman's Journal, Vol. VIII. 



