10 Theory of Agriculture. [Jan., 



in proximity to the roots, the very organs which nature seems to 

 have designed for taking up carbon, or nutriment, and conveying 

 it to the tissues of the plant. But that we may not be misunder- 

 stood w^e deem it proper to state that we by no means intend to 

 question the results of Saussure, Liebig or Bousingault in their 

 experiments on the action of leaves on the carbonic acid of the 

 atmosphere. But finding in soils and waters the nutriment of 

 plants, we infer it is from these sources principally that plants 

 derive their carbon and other matters necessary for their growth 

 and perfection. 



In our examination of soils of New- York, as well as many 

 others, we have taken one or two hundred grains and infused it 

 for several days in five or six ounces of rain water. We then 

 evaporate the solution in a porcelain dish, until it is reduced to 

 almost half an ounce; when the evaporation is completed in a 

 platinum capsule ; and we continue the evaporation until the con- 

 tents are perfectly dry, or even browned, in order to expel all the 

 water in combination with the residual matter. This is then 

 weighed in the capsule, previously balanced, while hot; then the 

 capsule wdth its contents is exposed to a red heat so long as it 

 loses weight. The loss is vegetable and animal matter; princi- 

 pally the former. 



Now the amount of soluble products obtained in this way va- 

 ries from 0.75 gr. to 2.00, sometimes more than two grains. The 

 soils which are known to be poor and unproductive, without ex- 

 ception, furnish the least vegetable soluble matter. 



Now the products obtained in this way consist of crenates and 

 apocrenates of lime, magnesia, or vegetable acids in combination 

 with alkalies and alkaline earths. Crenic acid is a yellow, un- 

 crystalizable substance, with an astringent taste, and soluble in 

 alcohol or water. The apocrenic acid is brown, uncrystalizable and 

 astringent, but far less soluble than crenic acid. They both re- 

 semble the ordinaiy vegetable extracts, and are undoubtedly taken 

 without change into the vegetable tissues by the roots. 



From these facts it follows, that the soil at any one time con- 

 tains a great abundance of the food of plants in a form and con- 



