DR. PRATT'S REPORT. 141 



underlie each acre. In fact, it seems there are 

 no rocks in this section which are not phos- 

 phates. 



" The area of this bed, containing phosphates 

 of good quality and in workable quantity, so far 

 as known and examined by the writer in person, 

 is not less than 40 to 50 square miles, though, 

 from samples I have examined from beyond these 

 limits, I am led to believe that the rock will be 

 found of good or indifferent quality, and in 

 greater or less quantity, over an area of several 

 hundred square miles. When of inferior quality, 

 they contain more sand, carbonate of lime, oxide 

 of iron, and phosphate of iron and alumina, and 

 proportionately less pure phosphate of lime." 



As the amount of this material is so large, it 

 will doubtless be the chief source of supply for 

 many years to come, and there will probably be 

 little variation in its price ; and as there are no 

 drawbacks or checks to the mining and economi- 

 cal transportation of it to all parts of the Atlantic 

 coast, we will estimate the value of insoluble 

 phosphoric acid from it. We give the following 

 table from Dr. Pratt' s interesting pamphlet on 

 the " History of the Discovery and Development 

 of the Native Bone Phosphates of the Charleston 

 Basin," giving analyses of different samples of 

 this guano, and of some other leading commercial 

 guanos, for comparison. 



