l^ NORTH-CAROLINA GEOLOGICAL SURVEY. 



Magneisa, 24 



Soluble Silica, 10 



Potash, trace, 



Soda 18 



The presence of phosphoric acid was not determined in 

 either of the foregoing, but as it is in combination with the 

 small per centages of oxide of iron and alumina, it is evident 

 that it exists in proportions less than that of the alkalies. 



The soils of Halifax, were originally sandy, yet the rela 

 tive proportion of sand, as they are now constituted, is con 

 siderably greater than when they were first brought under 

 cultivation. The soluble matters, those consumed by the 

 crops which they have borne, having been removed with 

 them, and nothing returned to supply their places, they are 

 yet capable of bearing very light crops, but it is doubtful 

 whether the cultivation of land so poor as these really pays. 

 If an example of poor soil is placed side by side with a good 

 one, the comparison is much facilitated: 



t- &amp;gt; ... . -*S4 



GOOD son. POOR son. 



Silex, 74.80 94.15 



Water, 4.90 1.30 



Organic matter, 5.40 1.35 



Alumina and peroxide of iron, 14.00 1.80 



Phosphoric acid, 51 



Lime, 40 15 



Magnesia, 20 01 



Potash, 25 01 



Soda, 13 01 



In making a safe comparison between the composition of 

 good and poor soils, it should be stated that less alumina and 

 iron would not displace the soil from the position I have 

 placed it. The silex is in the proper proportion, and the or 

 ganic matter may be regarded also as sufficient, though as 

 we shall see in the sequel, this element may be greatly in 

 creased to the advantage of long cultivation. Where it is 

 wholly absent, seed fails to ripen ; a fact which shows the 

 necessity of its presence. Silex is the basis of all soils, and 

 where it is entirely absent, barrenness is certain. It is sola- 



