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XXIV. On Fluorine. By G. J. Knox, Esq., and the Rev. 

 Thomas Knox.* 



AS far as the existence of a substance which had not hitherto 

 been procured in an independent state could be deter- 

 mined, the experiments and reasoning of Davy and Berzelius 

 are sufficiently conclusive. The only desideratum seems to 

 have been the obtaining a vessel upon which this energetic 

 principle would exert no action. Since fluorine shows no affi- 

 nity for the negative elements oxygen, chlorine, iodine, and 

 bromine, nor for carbon or nitrogen, it would appear that 

 the vessel to contain it should consist of some solid compound 

 of those substances; but as such vessels would be unable to 

 bear exposure to a high temperature, we considered that 

 though they might be convenient for retaining the gas when 

 once obtained, they would not answer for its production. It 

 was therefore necessary to employ some substance already 

 saturated with the element ; and for this purpose fluor spar, 

 from bearing exposure to a high temperature and being easily 

 formed into vessels, appeared best adapted. The most con- 

 venient method of obtaining the gas seemed to be by acting 

 upon fluoride of mercury with dry chlorine, by which means, 

 if the absence of moisture could be insured and the forma- 

 tion of a chloride of mercury obtained, fluorine must have 

 been disengaged, and if present would be recognised by ap- 

 propriate tests. 



Placing dry fluoride of mercury in the fluor-spar vessel, we 

 heated it till a glass plate cooled by the evaporation of sul- 

 phuret of carbon showed no trace of moisture in the vessel ; 

 the chlorine was then passed through a desiccating tube filled 

 with fused chloride of calcium, the tube being bent at an 

 angle, and its extremity drawn capillary, so as to enter the 

 vessel, which, when filled with the gas, had its orifice closed 

 with a plate of fluor spar which was fastened firmly down. 



After exposing it to the heat of a spirit-lamp for some time, 

 on removing the fluor spar cover, and replacing it rapidly 

 with one of silica, it showed immediate and powei-ful action. 

 The inside of the vessel was found on examination to be co- 

 vered with crystals of bichloride of mercury; both of which 

 results prove the presence of either fluorine or hydrofluoric 

 acid; to determine which, we repeated the experiment, 

 cooling the cover of the vessel so as to condense any hydro- 

 fluoric acid which might be present, but none appeared, from 



• Communicated by the Authors. 



N2 



