114 Seyherfs Analysis of various Minerals. 



C. After the separation of the Sihca from the liquor 

 (B,) the excess of acid was neutrahzed with ammonia,when 

 treated with the hydro sulphate of ammonia, it produced a 

 black precipitate ; this precipitate, washed and dried, was 

 calcined, in order to volatilize the greater part of the sul- 

 phur, it was then treated with a little nitric acid and expo- 

 sed to a strong red heat, it then weighed 0.04 grammes on 

 3 grammes, or 1.333 per 100. This precipitate on ex- 

 amination proved to be Alumina and Peroxide of Iron. 



D. When oxalate of Potash was added to the liquor (C,) 

 a voluminous precipitate was formed, which on exposure 

 to a high temperature, yielded 1.38 grammes of Lime on 

 3 grammes, or 4G.0 per 100. 



E. The liquor (D,) after phosphate of soda and ammonia 

 had been added to it, was boiled and was thus found to 

 contain only a slight trace of Magnesia. 



This mineral is composed in 100 parts of 



itaining oxygen. 



25.65 



12.9^ 



99.333 

 100.000 



000.667 



This Tabular spar is, therefore, a Bisilicate of Lime, 

 and its mineralogical formula is Ca S^. 



This substance, was by some mineralogists in America 

 and in Europe, supposed to be Icthyopthalmite, whilst oth- 

 ers considered it Tremolite. The above results prove, that 

 its composition differs essentially from that of the minerals 

 with which it had been confounded. On comparing the 

 external characters with Karsten's account of the Tafel- 

 spath (a mineral until lately, found only at Dognazka 

 in Hungary,) but more especially from its chemical com- 

 position, I determined it to belong to that species. " The 

 Tafelspath of Hungary is milk white, and consists of coarse 

 granular hexaedral portions intimately interwoven, alter- 

 nately channelled on the disjointed surfaces." According to 



