296 



2. A specimen of the better variety in Mr. Davis's pits, afforded 

 Lime, - . . . 20-6 > Carbonate of lime 36-8 

 Carbonic acid, - - 16-2 ) per cent. 



Greenish residue, clay and sand 



containing some oxide of iron, 63-0 

 Loss, - . . _ 00-2 



1000 



The shelly matter much decayed, consisting chiefly of Pernas 

 and Turritella. 



3. The Fairton marl affords from the best variety 



Lime, - - - . i9-0 ) Carbonate of lime 34 

 Carbonic acid, - - 15-0 ) per cent. 



Greenish residue of clay and 



sand, - - - . 65-5 

 Loss, - - - - 00-5 



1000 

 The shelly matter fragments of Perna. 



The inferior variety, consisting of sand with a little clay and 

 shells belonging to a species of oyster in an undecayed condition, 

 contained, in two examinations made, not more than four per 

 cent, of carbonate of lime, after the shells were picked out. 



Bog Iron Ores. — This district is characterized by an abundant 

 supply of bog iron ore, which sustains in fact a principal part of 

 its manufacturing industry. 



The origin of the deposits of bog ore of the region before us, 

 we can readily understand, by adverting to the very ferruginous 

 nature of nearly all the strata, both the greensand and the beds 

 overlying it. The water, not only in the marl region proper, but 

 throughout the adjacent tracts, contains very generally a consi- 

 derable quantity of the oxide of iron, which it procures in its 

 passage through the upper strata. Upon coming into the open 

 air it parts with the carbonic acid, the agent by which it is en- 

 abled to retain the oxide of iron in the dissolved state ; this it 

 quickly precipitates, and hence the accumulations of bog ore in 

 all situations where the low grounds are entered by springs 



