

6 ESSAY I. 



I mixed diluted acid of fluor, obtained as in Sec. VL, 

 with lime-water, upon which a white powder was immediately 

 precipitated. When nothing more would precipitate, the 

 water was found perfectly pure. The precipitate itself, 

 though not of a crystalline form, proved, however, to be the 

 same as fluor. It yielded phosphoric light when put upon a 

 red hot stone in the dark, melted by means of the blowpipe, 

 and still more readily by adding some gypsum. And when 

 this fluor, thus artificially produced, was again decomposed 

 by means of vitriolic acid, it showed itself to be the same as 

 the native. 



SECTION XL 



The white matter, which, during the processes (Sees. v. 

 VL), was deposited in the receivers, after being well 

 edulcorated and dried, showed the following properties : (1) 

 It was rare, friable, and white. (2) It was not sensibly 

 soluble in acids. (3) It did not make a tough paste with 

 water, but was loose and incoherent after being dried. (4) 

 It dissolved by boiling in lixivium tartari, and the solution 

 on cooling assumed a gelatinous consistence. (5) In its pure 

 state it suffered no change in the strongest heat ; but, (6) 

 When mixed with a little alkali of tartar, it frothed and 

 boiled in a melting heat, and formed a glass. (7) This glass 

 with three parts of fixed alkali melted in the fire to a bluish 

 mass, which, when powdered and put into a cellar, first 

 deliquiated, and then became gelatinous. The acids pre- 

 cipitated a powder from it. (8) It dissolved in borax without 

 any intumescence. These several properties show it to be 

 siliceous earth. 



