ON FLUOR 41 



became again gelatinous. A good deal of earth remained 

 behind, but did not adhere firmly to the retort, which was 

 smooth in the inside, and yet full of broad shallow ex- 

 cavations ; and it was evident that it is not a mere crust 

 which fixes itself to the glass in treating fluor mineral with 

 oil of vitriol, but that the glass is actually corroded, which 

 Mr. Monnet, contrary to all experience, denies. 



SECTION IV. 



I gave over my attempt to procure ether, thoroughly 

 edulcorated the jelly and the earth that remained in the 

 retort after the rectification, and precipitated the earth that 

 was dissolved by the water with spirit of sal ammoniac. 

 The quantity of earth amounted in all to 2 drms., and that 

 which had separated spontaneously from the spirit was 

 semitransparent. 



Neither of these earths suffered any change under the 

 blowpipe, but they both flowed on the addition of a little 

 salt of tartar. 



This was a large quantity of earth from 2 oz. of fluor ; 

 and it could not be estimated as the whole, since the first 

 process was cut short before it was completed. 



As this earth showed the properties of siliceous earth, 

 and the glass, which was so much corroded, consists in 

 great measure of it, the greatest part might come from 

 the glass, and the rest perhaps be a constituent part of 

 the fluor itself. 



SECTION V. 



In order to ascertain this, it was necessary to obtain 

 the fluor acid quite free from siliceous earth. I therefore 

 exposed the ley, which I had procured by the precipitation 



