of Organic Bodies, 7 



after carbonization are insoluble both in water and in muriatic 

 acid. But this insolubility in the solvents did not always 

 exist before carbonization; for many organic substances, which 

 in an undecomposed and not carbonized state are soluble in 

 water, frequently contain a large part of their inorganic con- 

 stituents in an unoxidized state. 



It is well known, that most of, but not all, those inorganic 

 salts which are insoluble in water are soluble in muriatic acid. 

 But those salts which are insoluble in this acid certainly very 

 rarely occur in vegetable and animal substances. The meta- 

 phosphates require most attention in this respect, since they 

 may exist in the carbonized substance ; and yet, on account 

 of their insolubility in water and muriatic acid, their presence 

 may only be detected after the destruction of the carbonized 

 mass. But it is evident, from the investigations which have 

 been made upon the inorganic constituents of vegetable and 

 animal substances, and which are described in the Appendix, 

 that these metaphosphates can rarely if ever be present, since 

 in most cases carbonate of potash may be removed from the 

 carbonized mass by water, and which, as is well known, can- 

 not exist simultaneously with metaphosphates at an elevated 

 temperature. 



We must next mention the remarkable occurrence of silica 

 in vegetables, principally in the stems of the Grasses and Equi- 

 setacece (Appendix V.). The silica is undoubtedly removed 

 from the soil by the plants in the form of silicate. It becomes 

 separated, however, from this silicate ; and the silica separated 

 forms the principal mass of the stem in several species o{ Equi- 

 setum and the Grasses. Of course it exists in them in the form 

 of perfectly oxidized silicic acid ; but in consequence of its in- 

 solubility in water and muriatic acid, the greater part of it is 

 found in the mass remaining after the exhaustion of the car- 

 bonized substance with water and acid. 



Hence on comparing the quantities of the inorganic sub- 

 stances which the seeds and the culm of grasses yield in the 

 aqueous and muriatic solutions of the carbonized substance, 

 and on the combustion of the latter, we find, in contradiction 

 to the above deteraiination, that the carbonized straw yields 

 far more fixed substances than the seeds. But this contradic- 

 tion is only apparent, because the substances obtained after 

 the incineration of the carbonized straw consist almost entirely 

 of silicic acid. 



A comparative examination of the inorganic constituents of 

 wheat and wheat-straw made by M. Weber, and which is fully 

 described in the Appendix (VI. and VII.), proves this beyond 

 a doubt. 



