No. 12. 



Agricultural Chemistry. — Germination of Seeds. 



371 



g'iven to the principal constituents of the 

 different kinds of soil. Fine sand and lime- 

 stone, in which there are no other inorganic 

 substances except silicious earth, carbonate 

 or silicate of lime, form absolutely barren soils. 

 But argillaceous earths form always a part of 

 fertile soil. Now, from whence came the 

 argillaceous earths in arable land ? what are 

 their constituents, and what part do they play 

 in forming vegetation ] They are produced 

 by the disintegration of aluminous minerals 

 by the action of the weather: the common 

 potash and soda-felspars, Labrador spar, mica, 

 and the zeolites, are the most common alumi- 

 nous earths, which undergo this change. 

 These minerals are found mixed with other 

 substances in granite, gneiss, mica-slate, por- 

 phyry, clay-slate, grawacke, and the volcanic 

 rocks, basalt, clinkstone and lava. In the 

 grawacke we have pure quartz, clay-slate, and 

 lime; in the sandstones, quartz and loam. 

 The transition limestone and the dolomitz 

 contain an intermixture of clay, felspar, por- 

 phyry and ciay-slate; and the mountain lime- 

 stone is remarkable for the quantity of argil- 

 laceous earths which it contains. 



" It is known that aluminous earths are 

 most widely diffused on the surface of the 

 earth, and as we have already mentioned, all 

 fertile soils, or soils capable of culture, con- 

 tain alumina as an invariable constituent. 



" There must therefore be something in alu- 

 minous earth which enables it to exercise an 

 influence on the life of plants, and to assist 

 in their development. The property on which 

 this depends is that of its invariably contain- 

 ing potash and soda. Alumina exercises only 

 an indirect influence on vegetation, by its 

 power of attracting and retaining water and 

 ammonia: it is itself very rarely found in the 

 ashes of plants, but silica is always present, 

 having in most places entered the plants by 

 means of alkalies. 



" In order to form a distinct conception of 

 the qualities of alkalies in aluminous miner- 

 als, it must be remembered that felspar con- 

 tains 17| per cent of potash, albite IH per 

 cent of soda, and mica 3 to 5 per cent : and 

 that zeolite contains 13 to 16 of both alkalies 

 together. Analysis has shown that clay-slate 

 contains from 2| to S^ per cent of potash, 

 and loam from \^ to 4 per cent of potash. If, 

 now, we calculate from these data, and from 

 the specific weights of the different sub- 

 stances, how much potash must be contained 

 in a layer of soil, which has been formed by 

 the disintegration of 40,000 square feet (1 

 Hessian acre) ofoneof these rocks to the depth 

 of 20 inches, we find that a soil of felspar 

 contains l,^^2,000 lbs. : clink-stone contains 

 200,000 to 400,000 ; basalt 47,-500 to 7.5.000 ; 

 clay-slate, 100,000 to 200,000; loam 87,000 

 to 300,000. Potash is present in all clays; 



according to Fuchs, it is contained even in 

 marl, so called in Europe: it has been found 

 in all the argillaceous earths in which it has 

 been sought, 



" The fact that they contain potash may 

 be proved in the clays of the transition and 

 stratified mountains, as well as the recent 

 formations surrounding Berlin, by simply di- 

 gesting them with sulphuric acid, by which 

 process alum is formed, (which is a sulphate 

 of alumina and potasia.) 



" When we consider this extraordinary 

 distribution of potash over the surface of the 

 earth, is it reasonable to have recourse to the 

 idea, that the presence of this alkali in plants 

 is due to the generation of a metallic oxide by 

 a peculiar organic process for the component 

 parts of the atmosphere ? This opinion found 

 adherents even after the method of detecting 

 potash in soils was known; and suppositions 

 of the same kind may be found even in the 

 writings of some physiologists of the present 

 day. Such opinions belong properly to the 

 time when flint was conceived to be a product 

 of chalk, a calcareous clay, because found 

 therein, and when every thing which appear- 

 ed incomprehensible on account of not having 

 been investigated, was explained by assump- 

 tions far more incomprehensible." 



For the Farmers' Cabinet. 

 Germination of Seeds. 



Mr. Editor, — In perusing the "Treatise 

 on Vegetable Physiology," of which mention 

 is made at page 360 of your last number, I 

 have been much interested with some remarks 

 on the germination of seeds and the particu- 

 lar views taken by the writer, of this most 

 important process of nature, which I deem 

 worthy to be offered for insertion in the Cabi- 

 net ; and should they meet your approval, I 

 shall be glad to see them introduced to your 

 pages, and am a constant reader. D. I. 



" The conditions requisite for the germina- 

 tion of seeds, are warmth, moisture, and the 

 presence of oxygen, the process being also 

 favoured by darkness ; and the influence of 

 each of these agents will be readily under- 

 stood. No vital action can go on without a 

 certain amount of heat; the germination of 

 the seed is, therefore, as much dependent on 

 warmth, as the hatching of an egg of a bird, 

 although the amount it requires is not so 

 great. Moisture is also required, for the con- 

 version into a fluid state of the dry nutriment 

 which has been previously stored up in the 

 seed; and no change can commence until 

 this be supplied. The presence of oxygen is 

 also necessary, because the conversion of 

 starch into sugar, requires that some of the 

 carbon of the former should be set free ; and 

 this can only be accomplished by the union 



