ESSAY II. 



ON FLUOR MINERAL. 1771. 



SECTION I. 



IN the year 1771, I had the honour to present to the 

 Royal Society some experiments made with fluor mineral, 

 which were inserted the same year in the Transactions, and 

 by which I proved that the constituent parts of this fossil 

 are calcareous earbh, and a peculiar acid, to which I gave 

 the name fluor acid. Two years afterwards, Mr. Boullanger, 1 

 in a little treatise, endeavoured to show that this acid was 

 nothing else than muriatic acid, intimately combined with 

 some earthy substance. A short time after this again, Mr. 

 Monnet 2 brought forward some experiments, made by himself 

 upon the same substance. He maintains that the acid 

 which I obtained from fluor mineral is only vitriolic acid, 

 volatilised by means of some extraordinary combination 

 with fluor. 



SECTION II. 



Thus we have three different opinions on the origin of 

 this acid. A natural philosopher who seeks for truth 

 will naturally wish to know which of these opinions he is 

 to follow. Far from adhering tenaciously to the pro- 

 positions advanced in my former paper, I shall shortly 



1 Experiences et observations sur le spath vitreux, ou fluor spathique, 

 par M. Boullanger, 1773. 



2 Observations de phys. de M. I'Abbe Rozier, torn. x. p. 106. 



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