Proceedings. 31 



allowed to dry on the rubber, soon destroyed its elasticity. 

 Rubber is rapidly destroyed by oxidation ; but the Chro- 

 mates and even Chromic acid, powerful oxidising agents, 

 regarded by chemists generally as fatal to rubber, had, he 

 found, little or no effect on it. The oxides and salts of 

 manganese had an injurious, and nitrate of silver a most 

 injurious, influence on rubber. There are many other salts 

 which have more or less destructive influences, but the 

 above are a few of the most curious examples. 



Ordinary Meeting, November i8th, 1890. 



Edward Schunck, Ph.D., F.R.S., F.C.S., President, in the 



Chair. 



The thanks of the members were voted to the donors 

 of the books upon the table. 



The following note from Mr. WILLIAM Brockbank, 

 F.L.S., F.G.S., was read : — 



"At the last meeting of the Society I communicated 

 the interesting discovery, by Mr. de Ranee, of Estheria 

 minutUy van Brodieana, at Alderley Edge. Mr. de Ranee 

 has since pointed out to me that Professor Rupert Jones 

 states that the variety Brodieana occurs in the *Lettenkohl ' 

 of the Baden Trias. This formation is on the lowest 

 horizon of the German Keuper, as is the Cheshire Keuper 

 * Building Stone,' and in this relation it is of great interest 

 to note that this is the formation in which the oldest known 

 mammal, Microlestis^ occurs on the Continent, the presence 

 of which in England was first made known, by Professor 

 Boyd Dawkins, in the Rhaetics of the West of England. 



