228 ASHES OF PLANTS. 



treatment the clay is decomposed. The nearly dry 

 residue is digested with dilute hydrochloric acid, the 

 solution filtered off, and analyzed as above, omitting 

 the determination of silicic acid. 



The residue left by hydrochloric acid is boiled for a 

 long time with a concentrated solution of carbonate of 

 soda, which dissolves the silica separated by the sul- 

 phuric acid. The filtered solution is acidified with 

 hydrochloric acid, evaporated to dryness, and the 

 silica filtered off. 



The portion insoluble in carbonate of soda may be 

 a mixture of sand, feldspar, and other minerals not 

 decomposed by sulphuric acid, which maybe separated 

 to some extent with the aid of a magnifier. In order 

 to decompose them they must be treated as in the 

 analysis of feldspar, No. 80. 



The greater part of the residue obtained in VI., pre- 

 viously to treatment with sulphuric acid, may be 

 mechanically separated, with tolerable accuracy, into 

 its constituents, by levigation. The residue is stirred 

 up with much water by means of a feather, and the 

 finer suspended portions, consisting chiefly of clay, N are 

 repeatedly poured off until only the grains of sand, 

 feldspar, &c., remain behind. - 



118. ASHES OF PLANTS.* 



Salts of KO, NaO, CaO, MgO, A1 2 3 , Fe 2 O 3 and MnO, 

 with 01, F, SO 3 , CO 2 , and SiO 2 . 



Manganese does not occur in all ashes, and is 

 seldom present in sufficient quantity to determine. 

 Fluorine has been hitherto found only in the stalks of 

 some of the Oraminacese. Alumina is an essential con- 

 stituent of the ashes of the Lycopodiacese, but is 



* By Professor Stadeler. 



