1824.] some Compounds of Fluorine. 101 



fixed attention — have engrossed it ; and a fertile field of disco- 

 very has thus remained where otherwise it would have been 

 exhausted. 



Fluor spar has decorated mineral cabinets from probably the 

 earliest period of their existence ; every tint with which chance 

 can paint it; each casual diversity of form and appearance under 

 which it may present itself have been long familiar, and its true 

 nature continues a problem ; and its decomposition by fire was 

 yet to be learned. 



Fluor Spar. 



If a very minute fragment of fluor spar is fastened by means 

 of clay* to the end of a platina wire nearly as fine as a hair, 

 which is the size I now employ even with fluxes, it will be per- 

 ceived on the first contact of the fire tc melt with great facility. 

 As the fusion is prolonged, the fusibility will decrease ; protube- 

 rances will rise over the surface of the ball ; it will put on what 

 is designated by the term of the cauliflower form ; and finally 

 become entirely refractory. On detaching it from the wire, it 

 will prove hollow. This little capsula being taken up again by 

 its side, and its edge presented to the flame, thin and porous as 

 this edge is, it will withstand its utmost violence. 



Such an alteration of qualities proclaims an equal one of 

 nature. I had no doubt that the calcium had absorbed oxygen, 

 and parted with fluorine ; that the mass had ceased to be fluor 

 spar, and was become quicklime. On placing it in a drop of 

 water my conjecture was confirmed ; a solution took place by 

 which test papers were altered ; a cremor calcis soon appeared ; 

 and on allowing the mixture to become spontaneously dry, a 

 white powder remained, which acids dissolved with effervescence. 



That the fluoric element was gone admitted not of doubt. To 

 pursue it in its escape ; to coerce it, and render it palpable to the 

 senses, could not be required to establish the fact. It may, 

 however, be done. 



The open tube described by M. Berzelius in his valuable work 

 on the blowpipe, is adapted to the purpose by an addition to it. 

 A small plate of platina foil, on a curved plate of baked clay, is 

 introduced a little way into one of its ends ; and secured by 



X-_jJ 



bringing with the point of the flame the glass into contact with 

 it. The body to be tried is fixed to this plate by means of moist 

 clay ; and may then be subjected for any time to any degree of 

 heat. 



Thus tried, fluor spar quickly obscured the glass by a thick 

 crust of siliceous matter ; and coloured yellow a bit of paper 

 tinged with logwood. 



* AnnaU for December. 



