524 Intelligence and Miscellaneous Articles. 



minerals, and is seen in isolated crystals in various stages of con- 

 version to hornblende. The material dissolved has rendered the 

 acid magma less acid, and has influenced accordingly the products 

 of final consolidation. The granophyre is roughly estimated to have 

 taken up about one-fourth of its mass of gabbro, and this material 

 has been derived, not from the rocks seen in contact with the 

 intrusions, but from some subterranean source. 



3. 4 Observations on the Geology of the Nile Valley, and on the 

 Evidence of the greater Volume of that Biver at a former Period.' 

 By Prof. E. Hull, M.A., LL.D., F.R.S., F.G.S. 



The author draws attention to the two great periods of erosion 

 of the Nile Valley, the first during the Miocene period, after the 

 elevation of the Libyan region at the close of Eocene times, and the 

 second during a ' pluvial' period extending from late Pliocene times 

 into and including the Pleistocene. He notes the course of the 

 river through escarpments of the granitic and schistose rocks of 

 Assuan, the Nubian Sandstone, the Cretaceous limestone, and the 

 Eocene limestone, and observes that in places the line of erosion of 

 the primaeval Nile was directed by dislocations of the strata. Evi- 

 dence of the unconformity of the Nubian Sandstone upon the granites 

 and schists of Assuan is given, and some observations made upon 

 the age of the different parts of the Nubian Sandstone. 



In the second part of the paper the terraces of the Nile Valley 

 are described, and full details given of the characters of a second 

 terrace, at a height varying from 50 to 100 feet above the lower 

 one, which is flooded at the present day. The second terrace is 

 devoid of vegetation, and its deposits have frequently furnished 

 river-shells such as Cyrena fluminalis, JEtheria sernilunata, Unio, 

 Paludina, &c. The second terrace is traceable at intervals for a 

 distance of between 600 and 700 miles above Cairo. Two old 

 river-channels are also described, one at Koru Ombo, and the other 

 at Assuan itself. The author discusses the mode of origin of the 

 second terrace and the old river- valleys, and believes them to be 

 due to the former greater volume of the river, and not to subsequent 

 erosion of the valley. He gives further evidence of the existence of 

 meteorological conditions sufficient to give rise to a 'pluvial' period, 

 and points out that other authors have also considered that the volume 

 of the Nile has been greater in former times. 



4. « The Fauna of the Keisley Limestone. — Part I.' By F. E. 

 Cowper Reed, Esq., M.A., F.E.S. 



LXI. Intelligence and Miscellaneous Articles. 



ON THE DIFFUSION OF METALS. BY W. C. ROBERTS-AUSTEN, 

 C.B., F.R.S., PROFESSOR OF METALLURGY, ROYAL COLLEGE OF 

 SCIENCE, 



Pakt I. — Diffusion of Molten Metals. 

 TN the first part of the paper the author alludes to some earlier 

 4* experiments he made in 1883 on the diffusion of gold, silver, 



