Action of the Atmosphere upon newly -deepened Soil. 473 



sources. So remarkable is the affinity of pure iron for oxyjren 

 that, when formed under certain conditions by depriving its oxide 

 of the oxyo^en throuj2^h the agency of hydrogen at a heat below 

 redness, on exposure to the air it at once takes fire, returning thus 

 rapidly to its original condition, as was remarked by Magnus. 

 Upon the whole it may be supposed that the chief atmospheric 

 agent by which iron will be affected is the oxygen, acting in com- 

 pany with moisture, and that tlie clianges thereby Induced greatly 

 modify the constitution of the mineral ingredients of the soil. 



It has been seen, then, that the influence which the atmospheric 

 forces exert upon the soil is very various and extensive. Their 

 action indeed is not rapid nor energetic, and a very perfect expo- 

 sure of tlie soil is necessary to catch much of the ameliorating 

 influence. It is not therefore to be expected that a barren soil 

 can be rendered fertile by mere exposure to the air, although it 

 were wrought with a perfection that would have satisfied even 

 Jethro Tull. Tlie importance, however, of taking advantage of 

 the manifold benefits to be derived from the air, it is hoped, has 

 been rendered evident in the course of this paper. It need 

 scarcely perhaps be said that stagnant water will completely 

 prevent any benefit that is to be looked for from this source, and 

 that in the case of wet land its drainage must first of all be 

 thoroughly effected. The ground being dry, and the rain conse- 

 quently enabled slowly to filter through the soil, the full benefit of 

 the atmospheric waters will be obtained. Unless in the case of 

 sloping grounds, little rain-water should run off the fields; almost 

 the whole ought to sink gradually through the soil as it falls. In 

 order, however, to gain the utmost advantage from the frosts and 

 atmospheric influences, as great a surface should be exposed to 

 the air as possible ; and the best way to effect this would seem, 

 in tlie case of ground under tillage, to be, to have the soil ploughed 

 up into ridges like potato drills, and to leave it in this shape 

 through the winter — a practice of which the advantage is well 

 known to gardeners. Sir Josepli Paxton, for instance, advises that 

 " the surface of all strong land should be laid up in ridges 

 during the winter, as the action of frost, by expanding the mois- 

 ture in it, leaves it when thawed in a fine pulverized, friable, or 

 loosened state, by which it is rendered fertile, and ready imme- 

 diately after levelling in favourable weather to receive the in- 

 tended croj)," Many other benefits, however, tlian those of the 

 frost will result. Are the oxygen — ammonia — carbonic acid — 

 nothing? Let the ajjricultural mind therefore be of good cheer; 

 the atmospliere is a force everywhere present; although his farm 

 may be like Justice Shallow's, " barren, barren," he has at least 

 this consolation — " Marri/, f/ood air ! "' 



