90 



Proceedings. 



two fields. A discussion on the possible cause of the phe- 

 nomenon ensued, in which Mr. W. THOMSON, Mr. H. 

 Grimshaw, and Professor Reynolds took part. It was 

 suggested that the erosion might be due to the attacks of 

 rats, to the perforation of a weak point in the pipes in con- 

 sequence of impurities in the water, and the subsequent 

 action of running water forcing a channel below, and to 

 possible galvanic action resulting from contact with matters 

 in the soil. The apparent absence of erosion in the interior 

 of the pipe was referred to as evidence against the erosive 

 action of impurities in the water. 



The introduction to Part II. of Dr. W. C. Williamson's 

 " General, Morphological, and Histological Index to the 

 Author's Collective Memoirs on the Fossil Plants of the Coal 

 Measures " was read. 



Mr. Harry Grimshaw, F.C.S., read a paper on "Recent 

 Developments in the application of Iron Salts to the Pre- 

 cipitation of Sewage." A discussion ensued, in which Mr. 

 W. Thomson, Dr. G. H. Bailey and Mr. Faraday took 

 part. 



1'^ HEVJYO 



