£50 Chemical Observations upon Spathic Iron. 



a positive manner by the former, and not recognised by the 

 latter; and, above all, the existence of magnesia, in variable 

 proportions, announced by M. Drappier, while no other 

 chemist had spoken of it, must leave our opinion uncertain 

 upon the exactitude of these analyses. A desire to explain 

 the doubts which might be raised upon these verv important 

 facts relative to metallurgy, determined me to examine this 

 species of ore again;, by taking specimens which presented 

 differences among them. 



I consequently cho^e, out of the fine collection of the 

 Council of Mines, two pieces of spathic iron ; one of them 

 was from Vaunavevs, the same from which' M. Drappier had 

 detached some fragments ; the other was from Allevard, but 

 very different iri its characters from that which M. Drappier 

 had received from M. llassenfratz. I shall subjoin the cha- 

 racters of both. 



Specimen from Vaunaoetjt: 



Specific gravity 3 - 6. 



Colour -brownish yellow. 



•Semitransparent. 



The fracture laminated and glittering. 



The laminae perfectly smooth, like those of calcareous 

 spar. 



Specimen from Allevard. 



Specific gravity 3-S4. 



Colour grayish. 



It is opake. 



The fracture is sufficiently glittering. 



Its crystallization is very confused, and its lamina often 

 rounded : the divisions of the fissures which traverse this 

 specimen have often a very black superficial colour, and 

 which has scarcely a metalfic lustre. I chose for the ana- 

 lysis the gray portions pretty well freed from the brown *. 



The process which I followed consisted in attacking, bv 

 the nitric acid, the ore reduced into fragments, in after- 



* By the dry method, -with an equal weigfct of vitrified borax and a tittle 

 oil, in a crucible lined with charcoal, to ]<)0 parts of crude ore, 84 was 

 yielded from the ore of Vaunavey.i, and 37-G from that of Allevard, on the 

 first esaay, and 38-2 in the second. 



wards 



