SOIL OF SALT MARSHES. 



339 



parts of the latter, when treated for a feAV days at an ordinary 

 temperature with diluted hydrochloric acid, produced a solu- 

 tion which contained : — 



Calcium oxide, 

 Magnesium oxide, 

 Alumina, 



Sesquioxide of iron, 

 Potassium oxide, . 

 Sodium oxide, 

 Phosphoric acid, . 



The sample from the middle or central section of the 

 marshes (the same spot from which water, sample No. II., 

 had been collected), consisted, to about two-thirds of its 

 entire thickness, of a brown root growth, with but a slight 

 admixture of a grayish blue silt, whilst its lower termination 

 (the remaining third) was mainly formed of soil. The bluish 

 gray soil, soon after an exposure to the air, showed in one of 

 its layers a considerable amount of oxide of iron, apparently 

 of an origin common with the magnetic iron ore, contained in 

 the sand of the beach. One hundred parts of the air-dry 

 mass, left, after a careful calcination, from 46 to 48 per cent, 

 of mineral matter. One thousand parts of the latter, when 

 treated like the previous sample, produced a solution which 

 contained : — 



Calcium oxide, 

 Magnesium oxide, . 

 Alumina, 



Sesquioxide of iron, 

 Potassium oxide, . 

 Sodium oxide, 

 Phosphoric acid, 



8.2 

 3.2 

 86.0 

 67.0 

 11.50 

 29.15 

 3.70 



parts. 



The sample from the lower section of the marshes contained 

 a much smaller quantity of vegetable matter than the two 

 specimens previously mentioned. One hundred parts of the 

 air-dry soil left, after a careful calcination, from 89 to 90 per 

 cent, of mineral matter, which in color (reddish) resembled 



