112 BOARD OF AGRICULTURE. 



them. The average size is about that of a man's fist ; the 

 surface of the nodules is very irregular, with holes running 

 deep into them, sometimes entirely through (formed by the 

 borings of the teredo.) 



" These nodules are compact, very hard, sometimes brown in 

 color ; when dug up, very much of the mud adheres to them. 

 If two fresh surfaces of fracture be rubbed together, a very 

 strong organic odor is evolved, which is so characteristic that 

 this is used as a means of detecting the phosphates throughout 

 the region. The odor is obtained from the dry as well as the 

 wet, from the hard and soft varieties. The amount of nitroge- 

 nous, organic matter is small, not exceeding 0.5 per cent, for 

 ammonia. On the bluffs the strata are much like those de- 

 scribed above ; but the sandy soil is apt to be deeper, which 

 places the stratum of nodular phosphates deeper. 



" Underneath these strata is a bed of phosphatic marl, which 

 rises in some bluffs thirty to forty feet above the surface of the 

 river, and which descends to a depth of several hundred feet. 

 This was penetrated by the boring of the Charleston artesian 

 well for three or four hundred feet. An analysis of this 

 phosphatic marl from a bluff on the Ashley River, gave the 

 foUowino; : — 



" The marl is in a fine condition, and can be obtained in 

 immense quantities at trifling cost and labor. 



" The nodular phosphates from these beds vary but slightly, 

 except that some of them have a higher percentage of iron or 

 of sand than the others. 



Analysis of a Nodular Phosphate from the Ashley, some fifteen 



miles from Charleston. 



Per cent. 



Moisture, water and organic matter, . . . . 6.00 



Sand and oxide of iron, 15.3 



Sesqui oxide of iron alone, 5.4 



