THE CHEMISTRY OF THE FARM. 497- 



throughout, and consisted in the proportion of vegetable matter. A poor 

 soil of any class was a soil which contained from to '5 of vegetable mat- 

 ter ; an intermediate soil must contain from '5 to 1*5 of vegetable matter ; 

 and a rich soil must have from 1*5 to 5 per cent, of the same. Any pro- 

 portion of humus exceeding 5 per cent., caused a transference of the soil 

 into the class of humus or vegetable moulds. 



vLhe (llicmkitrn of the J-arm. 



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N studying the actual composition of soils, it must be remem- 

 bered that the subject has a distinctly mechanical, or phy- 

 sical, as well as a chemical aspect. Chemical analysis 

 teaches us the proportion in which the various constituents 

 composing it are present. But how little light does this 

 throw upon the agricultural diameter of a soil ! We must 

 know something of the texture, and the many important 

 surrounding conditions already enumerated, as well as the 

 ultimate composition ; and hence inspection and a mechani- 

 cal analysis should precede the more elaborate processes of the labora- 

 tory. The proportion of stones, gravel, gravelly sand, coarse sand, line 

 sand, clay, organic matter, and moisture, are ascertained by simple, but 

 ! -contrived, means. To thoroughly understand the texture or nu - 

 i;ical nature of soils, their relations to heat and water must be taken 

 into account, and when this has been done, the purely chemical analysis is 



i'Ted much more useful. 



The chemical composition of the principal minerals composing the cry- 

 stalline rocks will naturally be found in all sedimentary Turks, although 

 in widely differing proportions; and they will also be found to occur in 

 all soils. The preci.su composition can only be discovered by analysis, but 

 infer that the leading constituent <>f a soil will be the same 

 as that which ^m- character to the rock from which it was derive. 1. Thus 

 ment will predominate in sandstone soils, the calcareous in 

 ksand ! I, and the arL,Mllaee.m> in .soils derived from the great 



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