THE FARMER'S MAGAZINE. 



39 



earth long buried, on being turned up to tlie surface, is 

 exposed to a number of new forces tending to make its 

 particles enter into fresli arrangements, and that among 

 these light is not the least prominent in its effects?" 

 As there are so many bodies in nature, both organic 

 and inorganic, which are sensible to the chemical influ- 

 ences of the sunbeams, it is evident that the mere 

 bhading or covering of land, or the opening up and 

 revealing it to the light, must afleet its condition ; and, 

 however delicate and minute may bo the changes ob- 

 served iu the apparatus of the experimenter, we should 

 remember that, wiien multiplied so as to become appli- 

 cable to hundreds of tons of soil, and thousands of cubic 

 feet of the atmosphere, their importance is far from 

 being infinitesimal and inappreciable. 



The second portion of Mr. Jamieson's prize essay 

 relates to the influence exerted by the constituents 

 of the atmosphere ; the first portion, as we have 

 already noticed, being devoted to a consideration of 

 the action of the sunbeams. \Ye will try to sifl out, 

 from the author's learned and most valuable accumu- 

 lation of facts and recorded observations in chemical 

 science, so much as appeal's likely to be useful to the 

 agriculturist. 



The atmosphere being a mixture of nitrogen, oxygen, 

 carbonic acid, nitric acid, and ammonia, while carbu- 

 retted hydrogen, sulphurous acid, phosphoric acid, 

 muriatic acid, sulphuretted hydrogen, and phos- 

 phoretted hydrogen have all been found in it, the 

 properties of the chief of these ingredients are passed 

 under review ; the greater part of the changes which the 

 mineral and organic matter of the soil undergo being 

 attributed to the action of oxygen. This element has a 

 very strong affinity for organic matter in a state of 

 putrefaction ; and water and dew are powerful agents in 

 effecting oxidation, from the large amount of this con- 

 stituent contained in them. Carbonic acid is formed 

 abundantly by the decay of dead organic matter, and 

 found in rain, in springs, and in all natural waters; 

 and it is mainly througli its slowly-operating, but mar- 

 vellously powerful solvent properties, that the mineral 

 matters of the soil are brought into form fit for being- 

 taken up by the rootlets of plants. The oxygen of the 

 air also, acting upon the organic matters in the soil, pro- 

 duces a constant, although a slow, evolution of carbonic 

 acid, which is absorbed by the moisture existing in the 

 soil ; and the air contained in the pores of the soil is often 

 proportionally richer in this gas than the atmosphere 

 is, especially after recent manuring. Ammonia and 

 nitric acid — the latter in much the largest proportion — 

 exist in the air, and are washed out of it by rains. The 

 first showers after dry weather bring down more than 

 the average quantity found in rain-water; and the 

 water of dew and fogs is much richer in ammonia than 

 the rain. The earth also greedily absorbs ammonia 

 from the air itself, each particle of the surface being 

 continually brought into contact with a fresh suj)ply, as 

 the air sweeps over the ground at a considerable velo- 

 city, " In addition to the ammonia which the atmos- 

 phere supplies directly, it furnishes it also indirectly 

 by its action upon the nitrogenised matters that may 



be in the soil." " An important action of the ammonia 

 is its power of dissolving the mineral matter of the soil. 



Some of the mineral constituents of plants are 



dissolved in the soil only by water containing carbonic 

 acid or some salt of ammonia." This dissolving power 

 of ammonia upon silicates, phosphates, and other earthy 

 matters of the soil, is perhaps a more important pro- 

 perty than its use merely as a supplier of nitrogen ; 

 and its being thus a means of introducing into the plant 

 some necessary substances vv^hich might without it re- 

 main in an insoluble form, may certainly be taken as 

 an explanation of the great discrepancy found between 

 thequantityof ammoniasupplied in manure and thesmall 

 proportion recovered in the ciop. The author alludes 

 to the possibility of drawing more largely than we do 

 at present upon these stores of the atmosphere, in lieu 

 of nitrogenous manuring — a practice which is in com- 

 plete and successful operation at Lois-Weedon, and 

 partially carried out in other culture. " When it is 

 considered that many of the nitrogenised constituents of 

 the crops seldom find their way into the dung- 

 heap, but are sent off the farm in the grain 

 and live-stock sold, and that nitrates and am- 

 moniacal manures are expensive articles to pur- 

 chase, then the amount of these ingredients of the at- 

 mosphere, as available sources of nitrogen to the soil 

 and the plants that grow upon it, becomes a very inter- 

 esting inquiry ; for if it can be shown that by certain 

 not-too -expensive modes of management the surfaces of 

 our fields can be made to catch enough of these sub- 

 stances for the wants of each crop, a great advantage 

 would be gained, and a standing difficulty be removed. 

 Liebig, in a recent publication, writes : " I consider 

 myself as perfectly justified in concluding, from my 

 experiments, that on ordinary farms— ^^roi'ifferf 2f;e ^ire 

 to the soil the proper physical quality and composi- 

 tion — there may be, by degrees, such an amount of 

 ammonia collected or condensed from the atmosphere 

 as to be more than sufficient, with the available mineral 

 constituents present in the soil, to obtain the maximum 

 of produce for each soil. This, of course, does not ex- 

 clude the feasibility of attaining a still higher produce, 

 if we increa-e the proportion of mineral and atmos- 

 pheric constituents in the soil." 



The action of the watery vapour diffused through 

 the atmosphere, and of rain water, is next taken into 

 consideration ; and the following are the inferences 

 from a great variety of facts, the collection of which 

 shows the author's intimate knowledge of all the 

 branches of his subject — " Rain-water, being derived 

 by the action of evaporation and wind from the sea, 

 may be the means of conveying a very sensible amount 

 of many salts to the soil." '' Rain-water, on reaching 

 the ground, begins to dissolve a part of almost every- 

 thing it meets with, in its passage through the soil, such 

 as carbonates and phosphates of lime, magnesia and 

 iron, silicates of lime, potash and soda, organic matters, 

 &c." " Water containing common salt has also a great 

 solvent power upon some substances, surpassing even 



that of carbonic-acid water Salt occurs largely 



in rain-water in some places, its solvent effect may 



