68 NORTH-CAROLINA GEOLOGICAL SURVEY; 



and weighing 303 Ibs. per acre. The percentage of composi- 

 tion is : 



LB8. 



Phosphoric acid, ... 33.00 



Sulphuric acid, 7.00 



Chlorine, 4.00 



Lime, , 7.00 



Magnesia, 5.0C 



Potash and soda, 135.00 



Silica, 39.00 



Oxideof iron, 36.01 



The potatoe plant abounds in the oxide of iron and pqtash, 

 and there is no doubt the character of the soil influences to a 

 considerable extent the quality of the tuber. 



40. Among the substances which of all others would be 

 expected to be destitute of inorganic matter are cotton wool, 

 and the fine fibre of flax. Indeed it was at one time main- 

 tained that, these substances w^ere composed of carbon, oxy- 

 gen and hydrogen, and hence would be entirely volatilized 

 by heat; and hence, too, as they were composed of those 

 bodies, their cultivation would not impoverish the soil,. pro- 

 vided the other parts were duly returned to it. But these 

 views proved fallacious. Prof. Shepard, on submitting the 

 cotton wool to analysis several years ago, found the percent- 

 age of the ash to be 0.9247, nearly one per cent. The ash,. 

 as obtained, gave the following results in his analysis,, viz: 



Carbonate of potash, (traces of soda,) 4-1.19 



Phos. of lime, (traces magnesia,) 25.44 



Carbonate of lime, 8.87 



Carbonate of magnesia, 6.85 



Sulp. potash, 2.70 ^ 



Alumina, (accidental,) 1.40 



Chjorides, potassium and magnesium, ) 



Sujp. qf lime, Phos, potash, oxide C 6.43 



of iron and ; loss, ) 



This analysis is quoted for the purpose of showing that the 

 finest fibre contain matter derived from the soil. So of the 

 finest flax fibre whose ash is found to contain : 



