12 ESSAY I. 



SECTION XXI. 



I sublimed one part of powdered fluor with two parts of 

 vitriolated volatile alkali (secret ammoniac of Glauber) ; and 

 obtained, first, some caustic volatile alkali, then a kind of 

 sal ammoniac. The residuum in the retort was vitriolated 

 lime (selenite) ; the acid of fluor consequently united in this 

 process with the volatile alkali, forming a kind of sal 

 ammoniac ; and its earth remaining in the retort, united 

 with the vitriolic acid of the vitriolated volatile alkali. I 

 dissolved this kind of sal ammoniac in lime-water, and 

 obtained a precipitate, which was regenerated fluor. On 

 mixing some of the same sal ammoniac with a solution of 

 vitriolated magnesia, a precipitation likewise took place. 



SECTION XXII. 



I exposed equal quantities of powdered fluor and 

 corrosive sublimate to sublimation. The mercurial salt 

 rose unaltered ; but a small quantity of muriatic acid went 

 over towards the end of the process. The residuum in the 

 retort was fluor unchanged. The muriatic acid obtained 

 in the receiver had been probably first disengaged from 

 the corrosive sublimate by the iron contained in the fluor ; 

 but was afterwards again separated from it by the too great 

 degree of heat, and was thus carried over into the receiver. 



SECTION XXIII. 



I exposed equal quantities of powdered fluor and 

 vitriolated mercury in a close vessel to the fire, and 



