NORTH-CAROLINA GEOLOGICAL SURVEY. 121 



among the most remarkable. The first is represented by the formula C^ 

 Hi4, Oi 2 ; the latter by C 40 , Hj 5 , 16 . These two acids, which are spontane- 

 ously formed, and are common in peat and other earths, differ from each 

 other in their relations to ammonia ; the first having no affinity for it, w r hile 

 in the latter it is so strong that it is difficult to separate them. In conse- 

 quence of this affinity, it no doubt forms an important element in produc- 

 tive soils. 



Another class of vegetable acids, which are also produced by the action 

 of oxygen on organic matter, is called the azotized, from the fact that they 

 contain nitrogen. These acids are the crenic and apocrenic of Berzelius. 

 Both are soluble in water and alcohol; the apocrenic less so than the 

 crenic. They form with alkalies and alkaline earths, soluble and insoluble 

 salts ; some of which are essential constituents of a rich and productive 

 soil. 



By the continued absorption of oxygen from the atmosphere, wood and 

 other organic matters are converted into a nutriment for vegetables. The 

 crenic and apocrenic acids are products of bodies which are nitrogenous 

 themselves; the nitrogen of which is retained through all the changes 

 which the organic matters pass. 



It seems to be established, then, that organic matter may be useful to 

 plants, and may promote their growth in various ways. This conclusion 

 might be made almost a priori, subsequent to the determination of the na- 

 ture of the bodies under consideration ; for it is well known that many 

 bodies require nitrogen; and it is ascertained that some of the organic 

 bodies contain, and others absorb and retain ammonia obstinately. And 

 each of these classes of bodies are soluble, and in a condition to be receiv- 

 ed into the vegetable system. 



If the foregoing considerations are true, why should farmers be taught 

 that the organic matter of decaying leaves and of their barn yards is use- 

 less? that it is a bad economy to spread it upon their fields, or plow it into 

 their soil ? We have sometimes wondered why it is that many intelligent 

 farmers hold book farming in such low repute. We, however, have been 

 satisfied as to the cause; when, for instance, doctrines are taught so con- 

 trary to their experience; and when they are told that they had better burn 

 their barn yard manure rather than carry it out to their meadows, we are 

 not at all surprised that they lose confidence in books, and hence often re- 

 fuse to receive many things which are really sound and valuable ; and this, 

 on account of the erroneous doctrines which come apparently from a re- 

 sponsible source. 



But to return to the consideration of ammonia in the soil. Chemists 

 are not agreed as to the processes by which ammonia is supplied to the soil. 

 That it exists there, and that it is provided for by certain chemical changes 

 is admitted. We have stated in a former article in this journal, that one 

 of the means by which it is restored to the soil is through the mutual in- 

 fluence of water and the protoxide of iron ; the latter substance having the 



