550 



On Chalk Marl 



dug out in masses weighing several tons each. Between these 

 masses of stone there are large fissures filled up with a rich unc- 

 tuous marl. In these^, when quarrying stones in hop-grounds, 

 the roots of the hop-plant are frequently found 20 feet and up- 

 wards below the surface. This rock is not used as manure, and 

 it decomposes very slowly ; but whenever it crops out or runs 

 near to and parallel with the upper soil the land is always of the 

 most fertile description. 



Analysis of the Firestone Rock (No. 5). 



Per Cent. 



Combined water with a little organic matter . 1*60 



Soluble in dilute acids, 83* 38 :— 



Silicic acid (silica) .... not ascertained. 

 Carbonic acid . . o . . ,35-47 



Sulphuric acid .a trace. 



Phosphoric 0*15 



Chlorine 0-4 



Lime 44 '90 



Magnesia ....... '28 



Potash -18 



Soda -30 



Protoxide and peroxide of iron . . , '60 

 Alumina ....... 1 '46 



Insoluble in acids, 15*02 : — 



Lime '41 



Magnesia . . , • , . , '10 



Potash -07 . 



Soda . -43 



Alumina with a little oxide of iron . . . '92 

 Silicic acid and sand . . . . .13*09 



100-00 



It will be seen that this rock differs from all the other strata 

 that we have yet described, in being a comparatively pure lime- 

 stone, containing 80 per cent, of its weight of carbonate of lime. 



No. 6. Fossiliferous Green Marl. — This is a ;^thin stratum, 

 usually found from 12 to 20 feet above the building-stone. It 

 varies in thickness from a few inches to 15 or 20 feet. Just at 

 the bottom of this marl the phosphatic fossils lie in the greatest 

 abundance. These, with the marl, have been fully described in 

 vol. ix. of the Journal, in the paper " On the Phosphoric Fossils 

 of the Chalk Formation." * 



* It may not be uninteresting to state, that since the discovery of these phosphatic 

 remains I have extensively and exclusively used the above fossils, as well as those still 

 more abundantly obtained from the lower greensand, as substitutes for bones in the 

 manufacture of superphosphate of lime for the use of my farm ; and that, both as 

 regards cheapness and efficacy, I have every reason to be satisfied with their employ- 

 ment for this purpose. — J. M. Paine. 



