Cultural First Principles. 383 



as clay, these properties merely depending on the fine state of division 

 of the matter. JNIore often, however, sand constitutes a light, porous 

 soil. It is at best a poor, unnutritious soil, though when fine, better 

 than pure clay or limestone. Clay is so compact, so slightly absorp- 

 tive, and so retentive of water, and yet so liable to become parched, 

 that it is unsuited to vegetation, yielding no nutritive matter, and 

 being with difficulty penetrated by the roots. 



Sand and clay mixed constitute loams, which are spoken of as 

 sandy or clayey if either constituent occurs in the proportion of two 

 to one. 



A sandy loam or rich sancl, with humus, constitutes the best forest 

 soil. 



Limcsione, in an earthy state, yields a very light porous soil, of a 

 light colour. It dries rapidly ; and thus, though of some nutritive 

 value, is by itself unsuited to vegetation, and does not afford a suffi- 

 ciently solid basis for large trees. Lime and clay mixed constitute 

 marl, a most excellent soil, suitable to all kinds of plants, and highly 

 nutritious. It exfoliates, or flakes off, when exposed to the air, and 

 constitutes a stiff or a light soil, according as it is argillaceous or 

 calcareous, i. e., as clay or lime predominates. 



We may also have a calcareous loam, in which a small proportion 

 of lime, say a quarter, occurs ; but a mixture of clay, lime, and sand, 

 in almost equal parts, forms a most excellent soil. 



Vegetable mould is valuable, since it absorbs and retains twice its 

 weight of water, which it gives up more easily than clay, but less so 

 than sand or lime ; thus it acts as a corrective, besides which it 

 renders the soil dark-coloured, and contains organic compounds in 

 abundance suitable for the nutrition of plants. 



The geology of the subsoil has often little to do with the topsoil, 

 which may be of glacial or alluvial origin, or may be so altered by 

 atmospheric agency as to be totally different in composition from its 

 original condition, as when carbonate of lime is dissolved out, leaving 

 the red residual soil on our chalk and other limestone hills almost 

 destitute of calcium. 



For most of the definitions and classifications in this paper I am 

 again indebted to Professor Bagneris's Manual. They seem to me 

 so clear and precise that I thought I could not do better than adopt 



them, 



{To he continued.) 



