ANALYSIS OF IRON SPAR. 357 



X. 



Chemical Examination of a Sparry Iron Ore, sent to Mr. 

 GuYTON by Bergman. By Mr. Collet-Descotils *. 



JL HE analyses of iron spar, that have been lately pub- Recent analyses 



lished, having exhibited results considerably different from °^ "^on spar 

 ^ '' contradictory to 



those obtained by Bergman, it was to be wished, that some Bergman's. 



of the species on which that celebrated chemist had operated 

 might be subjected to a fresh examination. In fact this was 

 the only method by which it could be known, whether these 

 differences arose from the composition of the ores them- 

 selves, or from mistakes in the analysis. Mr. Guyton, 

 who had received from the Swedish chemist a small specimen 

 of the very ore, that had been the principal subject of his 

 examination, having the goodness to break off some pieces a piece of the 

 from it, and entrust them to me to analyse, I have executed ^^""^ """^ ^^" 

 the task with all the attention I conld possibly pay to it. 

 The small quantity of iron spar I had at my disposal, it 

 being only 388 cent. [60 grs.], and the method I employed, 

 not allowing me to ascertain the proportion of the volatile 

 principles, I confined myself to the investigation of the 

 nature and quantity of the fixed; and I conceive it neces- 

 sary, to relate at large the means I employed, that i}\c che- 

 mical reader may be enabled to judge of the degree of con- 

 fidence to be placed on my results ; previously giving a brief 

 description of the specimen on which I opeP&ted. 



Its specific gravity, taken by Mr. Guyton, was 3*693. Its physical 



Its colour was brownish yellow. 



It was scarcely translucid. 



Its crystallization was a little confused : its laminae very 

 small, and a little twisted. 



This ore, reduced to powder, was dissolved with effer- Dissolved in 

 vescence in sulphuric acid diluted with water; and I took^'^^ 

 care to employ no more than was necessary, so that the li- 

 quor was without excess of acid. Some insoluble matter re- 

 mained, weighing 1 decig. [1-544 grs.], which was found 

 to be silex. 



* Aunales de Chemie. Vol, LVIII, p, 149. 



Th<? 



