202 Professor Gmelin's Analysis of a 



dissolved in water, in order to separate metallic platina, "which 

 had been formed, evaporated, and melted. There were obtain- 

 ed in this way, 0.215 gr. of sulphate of lithion — 0.067187 

 gr. of lithion = 4.792 p. c. These 0.215 gr. sulphate of li- 

 thion being deducted from the whole quantity of the sul- 

 phate, (= 0.394 gr.) there remain 0.179 gr. sulphate of potash 

 = 0.096785 gr. of potash - 6.903 p. c. 



It need scarcely be observed, that it was proved, by the 

 appropriate tests, that the salt considered as sulphate of lithion 

 was really nothing else ; and that it was converted into a 

 carbonate, in which form lithion is characterized by its slight 

 solubility, as well as by its action upon metallic platina, &c. 



This Mica is accordingly composed of — 



Silica, - - 52.259 (a) 



Aluinine, - - 28.345 (b) 



Protoxide of manganese, - 3.663 (c) 



Potash, - - 6.903 (d) 



Lithion, - - 4.792 (d) 



95.957 



2. Determination of the Quantity of Fluoric Acid. — In or- 

 der to determine the quantity of fluoric acid, the method used 

 by Professor Berzelius in his analysis of topaz was followed. 

 2.627 gr. of mica, finely cut, were ignited with three times 

 their weight of subcarbonate of soda. There were obtained 

 0.478 gr. of strongly dried fluate of lime = 5.069 p. c. of flu- 

 oric acid. This fluate of lime was decomposed by sulphuric 

 acid, the excess of acid, for the greatest part, driven off'by heat ; 

 and the mass then digested with alcohol, filtered, evaporated, 

 and ignited. But there remained no trace of phosphoric acid. 



This peach-blossom coloured Mica is therefore composed of — 



Silica, - 52.254 



Alumine, - 28.345 



Protoxide of manganese, - 3.663 



Potash, ... 6.90.3 



Lithion. - - 4.792 



Fluoric acid, - - 5.069 

 Traces of water, 



101.026 



3. Search after Oxide of Titanium. — Mr Peschier of Ge- 

 neva thought that he had discovered oxide of titanium in se- 



