of Organic Bodies. 177 



bonized mass, but almost all the potash is combined with car- 

 bonic acid, whilst the earths in the teleoxidic portion of the 

 carbonized mass are mostly combined with carbonic acid, and 

 partly with phosphoric acid. 



The fact that organic substances, the ash of which consists 

 principally of earths, may be very easily incinerated, whilst 

 those which contain a large amount of alkalies are very diffi- 

 cultly so, forms an important objection to the complete inci- 

 neration of the organic substance for the determination of the 

 amount of ash contained in it. For by the prolonged heat 

 required in the latter case, the greater portion, and frequently 

 the whole of the alkaline chlorides, especially the chloride of 

 potassium, is volatilized ; or by the action of Z'-phosphates 

 with the aid of water, or by the hydrogen evolved and the 

 oxygen of the air, muriatic acid is liberated, and they are 

 thus converted into c-phosphates. Carbonic acid is driven off 

 in the same manner. For this reason, in the incineration of 

 those organic substances which abound in alkalies, Wacken- 

 roder has proposed to mix them with a weighed quantity of an 

 earth, to prevent their fusion and to promote the ready com- 

 bustion of the carbon. 



Appendix III. and IV. 



Examination of the Inorganic Constituents of Rape-seed and 

 Rape-straw. By M. Weber. 



Aqueous extract, — The following are the per-centage re- 

 sults : — 



Chloride of potassium . 

 Chloride of sodium 



Potash 



Lime 



Phosphoric acid .. . 

 Sulphuric acid . . 

 Carbonic acid . . . 

 Silica 



96-51 100-41 



On calculating the salts from the constituents obtained, a 

 very large amount of free potash remains in excess, which 

 existed in the evaporated residue as hydrate of potash. The 

 apparently considerable loss arises from the water of the hy- 

 drate of potash not having been given among the constituents. 

 Moreover, on account of the large amount of fatty oil in the 

 seeds, a very large quantity of olefiant gas was evolved during 



Phil. Mag. S. 3. Vol. 35. No. 235. Sept. 1849. N 



