252 ./Yew Puhlicalions. [April, 



that a rotation of crops is indispensable to a successful agriculture; 

 and the theory is altogether probable that a particular crop ex- 

 hausts the soil of certain elements essential to its production, which 

 must somehow be supplied beibre a second crop of the same kind 

 can be grown on the same land ; but it would be extremely inte- 

 resting if the fact of such exhaustion, and its extent, could be more 

 particularly determined by a chemical examination of the soil which 

 has been cultivaterl. The beautiful theory ot' the great agricul- 

 tural oracle of the day, that certain mineral ingredients which are 

 always found in the ashes of plants, and \vhich are carried off when 

 these products are removed, and, being essential to vegetation, re- 

 quire to be either artificially replaced or supplied by a natural pro- 

 cess, — and that, the land being suffered to rest, or applied to a dif- 

 ferent production, the ordinary influences of air and moisture in de- 

 composing the rocks of the soil will renew the supply of the min- 

 eral elements which have been removed, — seeins to offer the de- 

 sired explanation; and the experiments to which this theory has 

 led, and which, under its influence, are now going on in various 

 parts of the country, must presently determine it, and, what is bet- 

 ter, show its proper application, and greatly simplify the process- 

 es of agriculture, reducing its expenses and giving comparative cer- 

 tainty to its results. 



"The operation of air and moisture upon the soil, the effects of 

 light, and electricity, and frost, upon vegetation, all admit to be 

 powerful ; but they are as yet only partially understood, and pre- 

 sent subjects of the most interesting inquiry. In the progress of 

 science, technically so called, we have much to hope for; but in 

 what it has already accomplished enough has been gained to 

 quicken, but very far from enough to satisfy, the appetite. One 

 of the most eminent agricultural chemists of the present day, 

 Boussingault, second perhaps to no other, has said, " A great 

 deal has been written since Bergman's time upon the chemical 

 composition of soils. Chemists of great talent have made many 

 complete analyses of soils noted for their fertility; still, practical 

 agriculture has hitherto derived very slender benefits from labors 

 of this kind. The reason of this is very simple; the qualities 

 which we esteem in a workable soil depend almost exclusively 

 upon the mechanical mixture of its elements; we are much less 

 interested in its chemical composition than in this; so that simple 

 washing, which shows the relations between the sand and the clay, 

 tells, of itself, much more that is important to us than an elabo- 

 rate chemical analysis," This is certainly a great confession for 

 an eminent chemist to make. 



"To exemplify the different results to which the most scientific 

 men arrive in these cases, I will refer both to Boussingault and 

 Von Thaer in respect to a simple point, the presence of the car- 



