352 ABSORPTIVE AND KETKNTIVE 



experiments carefully conducted, during the summer months, or during that period of the 

 year when vegetation is atrected by atmospheric changes. At any rate, experiments per- 

 formed during tlie winter, the early spring, or late in autumn, would not be so satisfactory 

 as during some portion of the period when vegetation is active and energetic. Experiments 

 were connnenced and pursued for a week or more, but they were suspended partly for 

 want of time at command, and partly from the fact, that all the experiments and obser- 

 vations appeared to lead to and establish the result, that the powers in question were in 

 the direct ratio to the quantity of organic matter in the soil, though modified by its state of 

 subdivision ; for it appeared, that when the subdivision was excessive, the soil absorbed and 

 retained water in its maximum degree; and when coarse, or but imperfectly divided, its 

 power of absorption and retention Were proportionally diminished : still it was evident, 

 that even when the organic matter was coarse, those powers were much greater than when 

 the soil was deprived of matter from the vegetable kingdom. The facts being estalilished, 

 that the power of absorption and retention are in the ratio of the quantity of organic matter, 

 modified by its state or condition, it shov/s that soils may differ in those powers, even wlicn 

 by analysis the amount of organic matter is nearly the same. It becomes important, tlicn, 

 in a practical point of view, to secure a proper degree of fineness in the vegetable and 

 animal matters which are added to soils, inasmuch as they will be nuich more eflfective 

 as fertilizers in a given period than if they were coarse ; for it is during the dry season, that 

 vegetables require a soil which is both absorptive and retentive. That soil which is ca- 

 pable of seizing atmospheric water, and holding it when the atmosphere is heated, is one 

 of the best constituted soils. 



The preceding observations, we believe, may be easily confirmed by other observers, if 

 they will but turn their attention to the varieties of loam, or any of the mixtures of sand 

 and organic matter, or organic matter and clay. " " r 



Another fact, which is equally important with the foregoing, and which was determined 

 while engaged in these experiments, is the order in which the different materials composing 

 the soils stand to each otiier, or the relations which they severally hold to each other in 

 their separate capacity. For example, it was observed that marls, or the finely divided 

 calcareous compounds, are quite powerful absorbers and retainers of water, being even 

 superior to clay and the argillaceous compounds, or to alumina in a state of great puritj-. 

 This result was quite unexpected ; as the conuiion and jtrevailing opinion is, and lias been, 

 that clays are the most active and energetic in tiieir powers of absorbing and retaining 

 moisture. 



In accordance, then, with these observations, we found that the materials which are 

 most influential in soils, may be arranged in the following order, when their relations to 

 water or moisture are considered : 1. Peat, or pure organic matter ; 2. Marl, or, to be 

 explicit and definite, freshwater or shell marl ; 3. Clay, and argillaceous conqjounds in 

 which this element is in excess ; 4. Loam, or the common soils as they usually occur ; 5. 

 Sandy loam ; 6. Sand. Each of these kinds of earth is influenced, in its power of ab- 



