( 14 ) 

 We can readily conceive of what great advan- 

 tage it would be to the farmer to know the ex- 

 act composition of the plants, and of the soil 

 which grows them ; and also of the manure de- 

 signed for their nutrition. Chemistry has al- 

 ready partially supplied these desiderata, and 

 its researches are certainly destined to play an 

 important part in agriculture. The utility of 

 such knowledge can be better made evident by 

 some examples. The vine, for instance, al- 

 ways contains a large proportion of tartrate of 

 potassa ; and it is obvious, that if neither the 

 soil or manure can furnish the base in sufficient 

 proportion, the vine will suffer and yield only 

 a meagre harvest; in fact, this happens under 

 many circumstances. Wheat contains phos- 

 phates in such amount, that its ashes frequently 

 yield one-half of their weight of phosphoric 

 acid. Now, the majority of soils contain only 

 traces of phosphates, and therefore it is of the 

 first importance that the manure intended for 

 the nutrition of wheat should hold an adequate 

 proportion. Straw, and the stalks of a great 

 number of plants contain a large proportion 

 of silica; grass or clover require abundance 

 of lime, and some other plants only prosper 

 by the assimilation of soda. These plants, there- 



