of Organic Bodies. 1 73 



The large amount of potash in the acid extract of the car- 

 bonized peas is very remarkable. The quantity of phosphoric 

 acid present is about sufficient to form with the lime and mag- 

 nesia 2CaO, PgOg, and 2MgO, P2O5; the calculated quantity 

 of phosphoric acid would then amount to 21*92 per cent. 

 Were it even admitted that the alkalies had formed with the 

 two earthy phosphates, compounds of c-phosphoric acid inso- 

 luble in water, the quantity of alkali would be far too great 

 for this purpose; for the potash alone requires more phos- 

 phoric acid than was found to form 3K0, P2O5. 



The amount of phosphoric acid found in the acid extract of 

 the carbonized pea-straw is exactly sufficient to form 6-phos- 

 phates with the lime and magnesia ; the calculated per-centage 

 of phosphoric acid would then amount to 18'53. But both 

 the salts undoubtedly exist in the carbonized residue in the 

 form of c-phosphates, and the amount of the carbonates of lime 

 and magnesia must be less by so much as is requisite to form 

 c-phosphoric acid from the 6-phosphates. 



Remaining carbonaceous mass. — The following is the com- 

 position per cent, of the ash obtained b}' incinerating the ex- 

 hausted carbonaceous mass of the peas and pea-straw. 



Peas. Pea-straw. 



Potash 24-14 



Lime 5*25 1-87 



Magnesia .... 11*22 14< 66 



Peroxide of iron . . 0-85 7"73 



Phosphoric acid . . 58*03 20*80 



Silica 0*51 54*94 



100*00 10000 



Considering the large quantity of phosphoric acid in the 

 ash of the peas, we must admit that one portion of the bases 

 is combined with rt-phosphoric acid, and another with Z'-phos- 

 phoric acid. If we calculate the lime and magnesia, as also 

 the small quantity of peroxide of iron as 6-phosphates (which 

 certainly ought not to be done in the case of the peroxide of 

 iron), 26"08 per cent, of phosphoric acid are required. If we 

 assume that the remaining 31*95 per cent, of phosphoric acid 

 are combined with the potash to form KO, Pg O5, we require 

 21-09 per cent, of potash. The quantity found is 305 per 

 cent, more than this. 



For the purpose of showing the important difference which 

 occurs when the incineration of the exhausted carbonized mass 

 is eillected by the aid of a solution of platinum, or by my 

 former method, by combustion in oxygen, the result of the 

 examination of the ash of this substance may be brought for- 



