GIVEN OFF BY PLANTS DURING THEIR GROWTH. 



41 



the means adopted for attaining the end and indications desired, 

 and against the competency of the results, when obtained, to 

 afford demonstration on some important points of the inquiry. 

 Yet it is not unadvisedly that some of them, at least, have been 

 risked, and especially in reference to the question of the exact 

 composition and resources of the soils employed, do we not 

 scruple to declare, though in opposition to the known opinions of 

 several esteemed chemical friends/ t that we are more disposed, for 

 the present at least, to rely upon the comparative indications 

 which a natural and unanalysed but exhausted soil may yield 

 alone, and in admixture with manures of known composition, 

 than upon one of an artificial kind, such as pure sand, for ex- 

 ample—or upon the results of analysis at the commencement of 

 the experiments. Indeed, in proof of the dangers and uncer- 

 tainty to which w r e are exposed in judging of the exact capabili- 

 ties of a soil by its analysis, and especially of an exhausted one, 

 wherein all the more important constituents are so small in quan- 

 tity, we need only call attention to the very elaborate examination 

 of this subject in the hands of Professor Magnus, as detailed in 

 his account, ' Uber Versuche betreffend die Erschopfung des 

 Bodens/ 



The knowledge we obtain by synthesis in the method adopted 

 and described further on, with the comparisons which will in 

 time be provided, is, we believe, our safer guide. Specimens of 

 the soil, as originally taken for the experiments, are, however, 

 preserved for analysis at some future time, when the whole sub- 

 ject of the composition and properties of soils can be entered into 

 — and when, also, by the continuous growth of the different 

 plants as proposed, the balance -of the constituents in the cases 

 of the several experiments will be so far affected as to yield 

 sufficiently wide variations, and therefore trustworthy points of 

 comparison. 



As already stated, the plants selected for experiment were — 

 Wheat, Barley, Beans, Peas, and Clover. Seeds of the first 

 four of these were sown in a box of mould, where they were 

 allowed to reach the height of about 3 inches before being trans- 

 ferred to the experimental pots ; but the Clover plant was 

 brought direct from the field. One or more of each description 

 of plant was grown in each of three different conditions of soil, 

 and each set of the five plants with the same description of soil 

 constituted a Series. An inspection of the following plan will 

 aid a conception of the arrangement of the experiments as to 

 condition of soil and description of plant : — 



