334 M. Berzelius on Fluoric Acid. [Nov. 



It is, therefore, a double sak with two acids, or at least an ana- 

 logous compound. 



I did not succeed in forming either a super or a subfluate of 

 barytes. 



Fluate of strontian may be prepared in the same manner as 

 the preceding, which it closely resembles in its inconsiderable 

 solubility in water, or an excess of fluoric acid. 



Fluate of Lime. — The best method of obtaining this salt arti- 

 ficially is to digest newly precipitated carbonate of lime in an 

 excess of fluoric acid. When thus prepared, it constitutes a 

 granular powder, which may be easily washed. When we 

 attempt to prepare it by mixing solutions of a neutral salt of lime 

 and a neutral fluate, it always precipitates as a jelly, which it is 

 impossible to wash, because it speedily stops up the pores of the 

 filter ; and it retains this gelatinous form even after having been 

 evaporated to dryness, and digested in water. Its deposition is 

 somewhat promoted by the addition of ammonia. Acids dis- 

 solve it slightly when newly formed, and the addition of an alkali 

 precipitates it from the solution unaltered. 



Sulphuric acid incorporated with finely pounded fluate of lime, 

 whether prepared artificially or the native spar, converts it into 

 a transparent syrupy mass, which may be drawn into threads ; 

 but no expulsion of acid takes place until the mixture is heated 

 to a temperature of about 100°. The addition of water to the 

 liquid renders it opaque, and causes the disengagement of fluoric 

 acid. Concentrated nitric and muriatic acids render fluor spar 

 transparent in ,-a similar manner, but the liquid is not so gluti- 

 nous, and the mineral is precipitated unaltered by water, if the 

 fluor spar contains the slightest admixture of silica, it instantly 

 effervesces -when mixed with sulphuric acid. 



Fluate of lime appears to be isomorphous with the fluates of 

 potash and soda. 



Fluate of magnesia is insoluble in water, and in an excess of 

 fluoric acid. 



Fluate of glucina is difficultly soluble in water ; but a solution 

 saturated in a temperature of 212° deposits on cooling minute 

 crystalline scales, which possess an astringent taste, and redden 

 moistened litmus paper. Neither this nor the preceding salt is 

 decomposed by ignition. 



Fluate ofi/tlria is nearly insoluble, even in an excess of acid ; 

 before being ignited, however, it has an astringent taste, and 

 reddens moistened litmus paper. 



Fluate of alumina is very soluble in water. A solution of it 

 when concentrated forms a clear uncrystallizable syrup, and 

 when evaporated to dryness, it leaves the salt in the state of a 

 transparent, yellowish coloured, friable mass, resembling gum 

 arabic. Thus prepared it is tasteless, and when put into water, 

 appears at first to be insoluble, but in the course of about an hour, 



