NORTH-CAROLINA GEOLOGICAL SURVEY. 123 



possession of the views of Mulder on this important subject; from which 

 it is well established that organic matter in soil is of the highest moment ; 

 and that it not only ministers indirectly to the growth of plants, as stated 

 in the early part of this article, but also becomes food itself in the form of 

 apocrenate of ammonia. So, also, that important substance, carbonic acid, 

 is liberated and furnished to the roots ; a substance which many suppose 

 is taken up by the leaves only. The apocrenates are continually forming; 

 not only the apocrenate of ammonia but also those of potash, lime and 

 magnesia. 



Through, then, the action of the organic acids the inorganic bodies are 

 received also into the circulation of vegetables ; and this gives us an idea 

 of its importance, namely, as a medium by which lime, magnesia and pot- 

 ash are supplied to the vegetable kingdom. The carbonates of lime and 

 magnesia are rather insoluble bodies, though the carbonate of soda and 

 potash are, as is well known, highly soluble. 



We should take an unsafe course in practice, then, in rejecting the or- 

 ganic part of manures ; and how truly important lime, potash, soda, mag- 

 nesia, &c., are; still, soils cannot be and are not fertile if they contain 

 only these ; and thp highest and most valuable soils are those in which a 

 due balance is preserved between the organic and the inorganic parts. 



90. Unfortunately for the best interests of agriculture, 

 the marls of North Carolina are too sandy to bear transport- 

 ation to distant points; and hence, their use is now limited 

 to the plantations upon which they are found. If, however, 

 a method could be devised by which the sand could be sepa- 

 rated cheaply from their useful parts, they would then be re- 

 duced in weight and bulk sufficiently to bear transportation 

 on those railroads which pass within three or four miles of 

 the beds in which they lie, and those especially upon the 

 Cape Fear and the Neuse might be transported very cheaply 

 by water. The quantity of sand, it will be perceived, is often 

 as&igh as 80 per cent. The remainder twenty per cent con- 

 tains all the fertilizing matter. This 20 per cent is a concen- 

 trated manure, and compares very favorably with the super- 

 phosphate of lime, especially, considering that its cost would 

 be very much less, or according to its actual cost, it would be 

 worth quite as much as the superphosphate. 



By aid of suitable machinery, it is highly probable the sand 

 may be separated rapidly from the valuable parts which com- 

 pose it. If so, the interests of agriculture would be greatly 



