268 Klaproth on the Chemical Analysis 



saturated by muriatic acid, was mixed with carbonate of po- 

 tassa, and the precipitate thus obtained being dissolved in 

 sulphuric acid, and mixed with acetate of potassa, afforded 

 nothing but crystals of alum. 



d. The other half of the precipitate b was digested in dis- 

 tilled vinegar ; the solution saturated by carbonate of ammonia 

 afforded a precipitate which, after due elutriation and ignition, 

 weighed 59 grains, and had the properties of pure alumine. 



e. The liquid remaining, after the separation of the precipi- 

 tate b, was evaporated to a small bulk, rendered neutral by mu- 

 riatic acid, and mixed with lime-water : a precipitate was thus 

 formed, having the properties of Jluate of lime ; acted upon by 

 sulphuric acid, it evolved glass-corroding fumes. 



The above experiments sufficiently demonstrate the existence 

 ofjluoric acid in the topaz, without accurately determining its 

 relative proportion. Experience leads me to believe, that the 

 loss in the earthy constituents does not exceed 1 per cent. ; 

 hence the deficiency of 5 per cent, may be referred to fluoric 

 acid, and the components of the pale yellow Saxon topaz may 

 be stated as follows : 



Silica a 55 



Alumina d 59 



Fluoric acid e 5 



Oxide of iron c a trace. 



Loss 1 



loo 



Analysis of Zoisit , from Carinthia. 



The specific gravity of the crystals of this mineral, used in my 

 analysis, was =3.315. 



a. 100 grains in fine powder were mixed with a solution of 

 250 grains of soda, and evaporated and fused in a silver cru- 

 cible ; the mass was softened with water, and dissolved in ex- 

 cess of muriatic acid, with which it formed a clear yellow solu- 



