468 Intelligence and Miscellaneous Articles. 



He referred to the evidence furnished by the Walton section (Q. J. 

 G. S. May, 1886), the Brookwood deep well (Geol. Mag. August, 

 1886), the contemporaneous denudation of the London Clay (Geol. 

 Mag. September, 1886) as affording further support to the view 

 which he has advocated ; gave six new sections on the northern 

 side of the area, showing (1) the attenuation of the Lower Bag- 

 shots beneath the Middle Bagshot clays, (2) the greater development 

 of clays towards the margin at the expense of the sands, (3) con- 

 temporaneous transverse erosion of the London Clay, (4) cases of 

 overlap, (5) the occurrence of massive pebble-beds at nearly the 

 same altitude along the northern Hank underlying (as at East- 

 hampstead and Bearwood) Upper Bagshot sands, and resting either 

 immediately upon, or in near proximity to, the London Clay ; and 

 added an account of his observations on the flank of St. Anne's Hill, 

 Chertsey, which he takes to be nothing more than an ancient river- 

 valley escarpment, subsequently eroded by rain-water, the hollows 

 thus formed having been subsequently filled up and covered over by 

 pebbles and other debris of the beds in the higher part of the hill, 

 these assuming the character of ordinary talus material. The con- 

 sideration of the southern margin of the Bagshot district is reserved 

 for a future paper. 



The Author considered that his main position, resting as it does 

 upon physical evidence, remains untouched by the attempt of later 

 writers to disprove it; while the disproof breaks down even on 

 its own lines (the stratigraphical), the paper in which this dis- 

 proof is insisted upon being characterized by (1) an incomplete 

 grasp of the problem on the part of its authors, (2) equivocal data, 

 (3) omission of important evidence, (4) inconsistencies, (o) erro- 

 neous statements. 



The Author (while correcting some errors of stratigraphical detail, 

 which appeared in his former paper, from insufficiency of data) 

 maintained that (though occasional intercalated beds with marine 

 fossils may be met with, as is commonly the case in a series of 

 delta- and lagoon-deposits) the view he has put forward is, in the 

 main, established ; and he proposed the following classification of 

 the Bagshot Beds of the London Basin : — 



Old Beading. New Beading. 



1. Upper Bagshot Sands =1. Marine-estuarine Series. 



2. Middle Bagshot Sands 



and Clays J> ==2. Freshwater Series. 



3. Lower Bagshot Sands 



LY. Intelligence and Miscellaneous Articles. 



ON THE INERT SPACE IN CHEMICAL REACTIONS. 

 BY OSCAR LIEBREICH. 



ACCORDING to all previous observations, it has been assumed 

 that a chemical reaction in liquids which are perfectly mixed 

 takes place uniformly and simultaneously in all parts unless cur- 



