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XXXI. Some Experiments and Observations on the Substances 

 produced in different chemical Processes on Fluor Spar. By Sir 

 Humphry Davy, LL, D, F. R. S. V. P. R. L 



Read July 8, 1813. 



In the Bakerian Lecture, for 1808, 1 have given an account of 

 an experiment on the combustion of potassium in silicated 

 fluoric acid gas, in which the gas was absorbed, and a fawn 

 coloured substance formed, which effervesced with water, and 

 left, after its action on that fluid, a residuum which burnt when 

 heated in oxygen, reproducing silicated fluoric acid gas ; and 

 I concluded from the phenomena, that the acid gas was de- 

 composed in the process, that oxygen was probably separated 

 from it by the potassium, and that the combustible substance 

 was a compound of the siliceous and fluoric bases. 



The experiment of burning potassium in silicated fluoric 

 acid gas was made likewise by M. M. Gay Lussac and The-!- 

 NARD, before I published any account of my researches on 

 this phenomenon. It was indeed one of the most obvious ap- 

 plications of potassium, and it occurred to many others, as 

 well as to myself, that it might be made, immediately after I 

 discovered that metaL 



M. M. Gay Lussac and Then ard drew the same conclu- 

 sions as I did, namely, that the acid gas was probably decom- 

 posed during the action of potassium on silicated fluoric acid ;: 



