1824.] Mineral Waters of Carlsbad. 129 



dient of the water, I pulverized a quantity of the sprudel- 

 stone which is deposited on the evaporating pans, mixed it in 

 a platinum crucible with concentrated sulphuric acid, and co- 

 vered it with a bit of glass coated with etcher's wax, and on 

 which I had scratched a few delineations. At the end of half 

 an hour the glass was found to be distinctly etched, and the air 

 within the crucible had also the smell of fluoric acid. 



I made numerous attempts, but for a long time fruitlessly, to 

 separate fluoric acid immediately from the residue obtained by 

 evaporating the water, and, in particular, from the precipitate 

 which is produced by ammonia in a solution of the earthy mat- 

 ter in nitric or muriatic acid. For this purpose I ignited the 

 precipitate, and treated it with sulphuric acid. My failure 

 arose from the silica in the analysis of these residues, being in 

 a peculiarly soluble condition, forming doubtless a fluosili- 

 cate, which was so thoroughly saturated with silica, that when 

 the precipitate was calcined, the whole of the fluoric acid was 

 volatilized in combination with the earth. Hence when I de- 

 composed the precipitate, without subjecting it to a previous 

 ignition with sulphuric acid, and made the extricated gas to 

 pass through a solution of carbonate of soda, I obtained both 

 the silica and the fluoric acid, the former diffused through the 

 liquid, the latter in a state of solution, and easily precipitable 

 by the usual treatment with a salt of lime. The quantity how- 

 ever was too small to admit of its weight being determined with 

 precision ; nor had I at my disposal a sufficient stock of the 

 water for repeating the analysis on a larger scale. I had there- 

 fore recourse to the sprudelstone, in which 1 had reason to 

 believe the carbonate and fluate of lime exist in the same rela- 

 tive quantities as in the water ; because, as shall be subse- 

 quently proved, they are both held in solution by carbonic acid, 

 and must therefore precipitate together in proportion as the 

 solvent is dissipated. 



The sprudelstone selected by me for this examination had 

 been formed in the establishment where the Carlsbad salts are 

 prepared. This establishment consists of a large basin, through 

 which the whole of the annexed water of the Sprudel is made 

 to flow, and in which there are placed side by side a number of 

 flattish tin vessels also filled with the water. The tin vessels are 

 thus situated in a kind of balneum marine, and they are main- 

 tained in this temperature, until the solutions contained in 

 them begin to crystallize. On the outer side of these vessels 

 the water in the basin deposits an incrustation of sprudelstone, 

 which gradually increases in thickness. The thickness of the 

 specimen which I analyzed was about a quarter of an inch. 

 Its fracture was crystalline and stiiated, and its specific gra- 

 vity was 2*84: in both of these characters, therefore, it had a 

 striking resemblance to arragonite. 

 Veie Series, vol. vin. k 



