496 



PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May IC, 



No. 4. — Blue clay, from the Forest Marble. (This soil is greatly improved by 

 top-dressing with bm"nt clay.) 



Moisture 



Water of combination, and a little organic matter 



Soluble in 

 ' dilute muri- 

 atic acid. 



Carbonate of lime 



Carbonate of magnesia 



Oxides of iron and alumina 



Potash -35. Soda -IS 



Magnesia in a state of silicate ^ f 



Potash in a state of silicate I Insoluble in j 



Alumina [ dilute acid. 1 



SUica J L 



2-37 

 5-38 



31-38 

 204 



11-90 



•53 



1-52 



1-29 



7-43 



36-16 



100-00 



Remarks on the above Analyses. — Dr. Voelcker is of opinion that 

 the soils of the Cotteswold Hills are the products of the decompo- 

 sition of the strata on which they rest. It may, however (supposing 

 this hypothesis true), appear surprising that there is not a greater 

 amount of carbonate of lime in soils which rest on limestone rocks ; 

 but the fact is, that a large proportion of this constituent is being 

 constantly dissolved and carried away into the substrata by the in- 

 filtration of rain-water charged with carbonic acid. This theory, as 

 to the origin of these soils, is also in unison with the observations of 

 Professor Buckman, who has so fully illustrated the mutual illations 

 subsisting between the soils and subsoils, and the changes in the one 

 consequent on the changes in the other. We may therefore consider 

 it as an established fact, that the soils of the Cotteswold Hills cannot 

 be considered as a " Drift," derived from aqueous deposition, but as 

 being due solely to atmospheric agency. 



