388 Geological Society: — 



abstruse and general discussion would fail to instil into him. 

 We can strongly recommend the book to all students of chemical 

 theory. 



The first five chapters deal with general theoretical consider- 

 ations, in which the notion of chemical potential plays an important 

 part. The remainder of the book is devoted to applications and 

 illustrations of the theory. In Chapters VI. to XI. the author 

 studies changes of physical state and analogous phenomena, various 

 cases of dissociation, solution, systems having only a single phase 

 of variable composition, and mixtures which arrange themselves 

 in layers. The last six chapters (XII. to XVII.) are devoted to 

 the theory of gases, dilute solutions, and osmosis. 



Percentage Tables for Elementary Analysis. By Leo F. Guttman>', 

 Ph.D., A.G.G.L, A.l.C. London: Wbittaker & Co. 1904. 

 Pp. vii + 43. 

 These tables will be found extremely useful in calculating the 

 percentage of carbon and hydrogen in a substance which on com- 

 bustion yields carbon dioxide and water. We would suggest the 

 omission of the "so" before "multiply''' and " divide " on p. vii, 

 this form of expression being a German idiom but not an English 

 one. 



Memoire sur la Reproduction Artificielle dn Bubis par Fusion. Par 



A. Verneuil. Paris : Gauthier-Villars. 1904. Pp. 30. 

 This pamphlet, which is reprinted from the Annates de Chimie et 

 de Physique, contains an interesting account of the author's experi- 

 ments on the artificial production of rubies. The problem, it seems, 

 is an extremely difficult one, and although very small rubies were 

 obtained whose physical and chemical characteristics were indis- 

 tinguishable from those of the natural product, yet all attempts to 

 produce larger sizes failed. 



X X XVII T . Proceedings of Learned Societies. 



GEOLOGICAL SOCIETY. 

 [Continued from p. 288.] 



December 21st, 1904.— J. E. Marr, Sc.D., F.K.S., President, 

 in the Chair. 



HE following communications were read : — 



T 



1. 'On Certain Genera and Species of Lytoceratidac.' By 

 S. S. Buckman, F.G.S. 



2. * The Leicester Earthquakes of August 4th, 1893, and 

 June 21st, 1904.' By Charles Davison, Sc.D., F.G.S. 



The earthquake of 1S93 was a twin, with its principal epicentre 

 between Markfield and Woodhouse Eaves, and the other near 

 Tugby, about 17 miles to E. 34° S. Its disturbed area contains 

 about 2200 square miles. In the north-western focus, the originating 

 fault hades to the north-east, and is probably one of the group of 



