CHEMICAL ESSAYS 



ESSAY I. 



ON FLUOR MINERAL AND ITS ACID. 1771. 



SECTION I. 



FLUOR mineral is a kind of stone, especially remarkable on 

 account of the beautiful phosphoric light which it yields in 

 a dark place when it has been heated. But its constituent 

 parts are as yet little known. In order to discover them, 

 I made several experiments with this substance. I made 

 use of two sorts, one of a green colour, found at Garpenberg, 

 and a white species from Gislof in Scania. 



SECTION II. 



It is well known that fluor mineral, after having been 

 once thoroughly heated, loses its power of becoming phos- 

 phoric for ever after. In order to find out whether it 

 thus loses any of its constituent parts, I exposed 3 oz. in a 

 covered crucible to a strong fire, so that it was thoroughly 

 heated. It decrepitated, as soon as it grew red hot, with a 

 loud noise, very like common salt. I took it out of the 

 furnace, and found, after it was cooled, that it had lost 

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