224 GEOLOGY AND CHEMISTRY OF SOILS. 



the whole science of agricultural chemistry ; a fact, however, 

 which has constantly made its appearance in these analyses, 

 viz. that the quantity of soluble geine in the soil A. is nearly 

 double of that in the soil B, and the insoluble geine is more 

 than three times the quantity. What inference is more obvi- 

 ous or certain than this, that the cultivation of the soil re- 

 moves its soluble geine and favors the conversion of the in- 

 soluble portions into those which are soluble ; and that vege- 

 table matter is not added* to the soil by cultivation, but ab- 

 stracted from it, and unless this is supplied, the land will, in 

 time, become exhausted and consequently barren. Thus it is 

 that theoretical deductions confirm actual experience. 



These results are confirmed by the analysis of the soils of 

 Massachusetts; and hence. Dr. Samuel L. Dana of Lowell 

 has proposed and advocated a theory of great practical im- 

 portance to the farmer, that the mineral ingredients of the 

 soil are of little importance, but that salts and geine (soluble 

 vegetable matter) are the sources of fertility in all soils. The 

 great object of analysis is to ascertain the condition of the 

 organic matters in the soil, and the means of improvement, 

 viz. the conversion of insoluble into soluble geine. 



There are facts which show, that alkalies are equally im- 

 portant with geine, and the labors of Dr. Dana and Prof. 

 Hitchcock establish this fact beyond a doubt. Liebig at- 

 tributes to the alkalies and salts a less extensive, but more 

 direct agency, in producing fertility, than has generally been 

 supposed. 



The amount of alkalies is given in only a few soils whose 

 analyses have fallen under our notice. But as the alkalies 

 are found in plants, and exert a powerful influence in vege- 

 tation, it may be interesting to make some few calculations 

 as to their amount, in order to see if they are in fact essential 

 to fertility. In making these calculations, we will give the ab- 



* Unless it is in wood lands or peat meadows, in which case large 

 quantities of vegetable matter are derived from the atmosphere. 



