ipS GEOLOGY AND CHEMISTRY OF SOILS. 



II. Chemical Analysis of Soils. 



Object of this analysis. The object of this analysis is to 

 ascertain the water of absorption ; the quantity of soluble 

 geine, which will indicate the quantity of food already pre- 

 pared for vegetables ; the amount of insoluble geine, which 

 will show what food is unprepared as yet for the plant ; salts 

 of lime and mineral constituents. The latter may all be re- 

 duced, according to Dr. Dana, to granitic sand; that is, the 

 earthy ingredients of all our soils, are composed of the fine 

 detritus of granite, gneiss, mica slate and argillite. Now, as 

 these earthy ingredients may vary considerably in their pro- 

 portions, without affecting the fertility of the soil, they are al- 

 ways prepared for their office, and are only changed for the 

 better by cultivation. But this is not the case with salts and 

 geine. Any considerable variation here, will cause barren- 

 ness. Salts and geine are the substances which are remov- 

 ed by the plant, and must therefore be constantly supplied to 

 the soil, or the land will soon become exhausted. The great 

 object then of analysis, is to determine the quantity of solu- 

 ble and insoluble geine and salts. This is all the farmer 

 needs to know, which may not be learned by inspection of the 

 soil, or by the descriptions which have already been given. 

 The relations of the soil to heat and moisture, depend chief- 

 ly upon geine. The larger the quantity, the greater the ab- 

 sorbent power of the soil, both as respects water and ca- 

 loric. 



Mode of Analysis. 1. To determine the absorbent power 

 of soils, sift the soil through a fine sieve, and take a quantity 

 of the finer portions, and heat it to 300° F. Then weigh out 

 100 grains on a piece of glazed letter-paper, expose it to the at- 

 mosphere from 24 to 3G hours, weigh again, and the quan- 

 tity gained will be the absorbent power of the soil. Note 

 this in a Journal kept for the purpose. 



2. To determine the quantity of soluble geine. Bake the 



