neighbourhood of Cirencester. 



325 



favourable for corn ci'ops, which is far from usually being the 

 case with those either of the Inferior or Great Oolitic beds ; in- 

 deed our observations of crops upon what the Cotteswold farmer 

 calls " stone brashes " of the district, when compared with the 

 Cornbrash, would lead us to conclude the following as a faif 

 average grown upon an acre in bushels : — 



The average rent may perhaps be gathered from the following 

 table : — 



the acre. 



1 . Stonebrash, Inferior Oolite 7*. to 20s. 



2. Stonebrash, Great Oolite 14s. to 25s. 



3. Cornbrash 20s. to 40s. 



This great difference in the productive powers of soils, which 

 a cursory examination only would lead to the conclusion were 

 nearly alike in character, may, to a considerable extent, be ex- 

 plained by the following analyses, which were made by Professor 

 Voelcker from specimens which I had the pleasure of procuring 

 for him ; and it may be remarked in passing, that as the analyses 

 were made by the Professor in order to ascertain the different 

 constituents of the rocks and not the soil, in each case typical 

 hand specimens were presented to him, and the result singularly 

 explains observed facts with regard to the crops upon the re- 

 spective substrata. 



Result of analyses by Professor A. Voelcker : — 



Inferior Oolite. Great Oohte. Cornbrash. 



Carbonate of lime 



Magnesia 



Sulphate of lime 



Oxide of iron 



Alumina 



Phosphoric acid 



Soluble silica 



Insoluble siliceous matter.. 

 Alkaline salts 



89-20 

 •34 

 •09 



4-14 



•06 



2^75 



327 



undetermined, 



99 85 



95-346 

 •739 

 •204 



1-422 



-124 

 1-016 



-533 

 undetermined, 



99-384 



89-195 

 •771 

 -241 



2-978 



•177 



1-231 



4-827 



undetermined- 



99-420 



