244 Dormant and Active Ingredients of the Soil. 
sated by an increased amount of soda, and the same remark seems 
to apply to the acids. 
Slill we have not as yet sufficient data for determining: to what 
extent this exchange of the usual ingredient for another can take 
place ; whether indeed the same organ, or the same proximate 
principle belonging to the plant, mav admit at all of this change 
in its constitution taking place ; or if it can, in what degree the 
presence of this new principle may affect its healthy develop- 
ment. 
By turning to the Table which states the relative quantities of 
alkaline ingredients extracted by water impregnated with car- 
bonic acid from the different soils, it will be seen that in most 
of these the amount of soda predominated over that of potass, and 
yet the latter alkali was principally found in their ashes ; an indi- 
cation at least of some superior adaptation of potass to soda with 
reference to the organization of plants.* 
Again, it is remarkable, that whilst in several of the soils soda 
appeared to exist in the form of a carbonate (since the quantity of 
chlorine was so small that only a minute trace of it was discover- 
able in them), in many of the ashes of the plants only as much 
soda was detected as would contain sodium equivalent to the 
chlorine present. 
Hence it would seem to follow, that common salt, when it acts 
beneficially upon land, does not assist the crop by virtue of the 
alUali it imparts to it, but operates in some other as yet unex- 
plained way ; and that it is still questionable, at least in the case 
of terrestrial species, whether plants have the power of decom- 
posing chloride of sodium, and of separating its chlorine. 
Lastly, the analyses contained in tiiis paper may be of use at 
the present moment, bv contributing to show how much still 
remains to be done, before we can flatter ourselves at having 
attained any sure knowledge of the normal constitution of plants, 
or of the range of variation of which under natural circum- 
stances it is susceptible. At a time when certain enlightened 
members of the Royal Agricultural Society have prevailed upon 
that great Body to devote a portion of their f unds to the prosecu- 
tion of the chemical analysis of the ashes of vegetables, whatever 
tends to render more palpable the importance of such an investi- 
gation may be of service, in aiding their meritorious efforts to 
giv<! a more scientific direction to the incjuiries which such Asso- 
ciations arc intended to promote, and in vindicating the utility of 
the course which they have in this instance adopted. 
* This is also shown very strikingly in a paper on the analysis of Fiici 
read to the British Association at Cambridge, by Mr. Schweitzer, in .hiiie, 
1845. 
