] 22 Proceedings of the British Association, 



the proportion of these bases one to the other varied considerably, 

 a circumstance at first sight appearing to confirm the theory of 

 substitution. The author however conceives that this may be ex- 

 plained, by supposing a different degree of developement of the 

 several parts or proximate principles in the respective samples, as 

 he finds a great discrepancy in the amount of phosphoric acid in 

 gluten and in starch, and thinks it probable that the same diversity 

 may extend to other of the principles contained in each plant. That 

 potass is better adapted for the organization of a plant than soda, 

 seems to follow from the circumstance, that whilst the soil usually 

 contained an excess of soda, the plant always was most rich in potass. 

 The author, therefore, in accordance with the views of Liebig, throws 

 out as a conjecture, that the soda found in the ash may be that 

 circulating through the vegetable tissue, and contained on the top, 

 whilst the potash is actually assimilated, and constitutes a part of the 

 vegetable tissue. The former, as Liebig supposes, may be useful 

 in conveying carbonic acid to the plant, but cannot be substituted for 

 potass, at least without injury to its healthy condition. It appears 

 also, from the analyses referred to, that land plants have not the 

 power of decomposing common salt, so that this substance cannot, 

 as has been supposed, be serviceable to vegetation, by supplying it 

 with alkali. We may also infer, that it does not follow, because a 

 soil is benefited by manuring, that it is destitute of the ingredients 

 which the manure supplies, since it may happen that these in- 

 gredients are present in the soil in an insoluble, and therefore not 

 an available condition. Chemical and mechanical means may no 

 doubt be effectual in bringing into a soluble condition the phosphates 

 and alkaline salts thus locked up within the soil, but as this is 

 brought about by Nature herself, we are counteracting her beneficial 

 effects when we waste the products of these operations, ready pre- 

 pared for our hands, as is done in suffering to run to waste the 

 various excrementitious matters which are placed at our disposal. 

 The analyses given may also show, from their great discrepancy with 

 those of Sprengel, the importance of that investigation of the con- 

 stituents of the ashes of plants, now about to be undertaken under 

 the auspices of the Royal Agricultural Society. The author also 

 conceived that the line of research which he had pursued might be 



