346 Geological Society: — 



metal against the atmospheric pressure, which for most liquids 

 lias heen found to be about one-eleventh of the total latent 

 heat. Thus for the vaporization of a gramme-molecule of solid 

 Zn and of solid Cd ? without performance of external work, we 

 have the approximate values 27 and 28 respectively, while the 

 value adopted on p. 18 of my paper is 29*6 for both of them. 

 This agreement should increase the confidence to be placed 

 in the estimates of the latent heats of the other metals and 

 compounds given in that paper. It should interest therm o- 

 chemists to learn that the work of Barus shows how a number 

 of important latent heats can be determined experimentally 

 with the aid of thermodynamics. 



XXXI V. Proceedings of Learned Societies. 

 GEOLOGICAL SOCIETY. 

 [Continued from p. 260.] 

 May 18th, 1898.— W. Whitaker, B.A., F.E.S., President, 





T 



in the Chair. 

 HE following communications were read 



1. 'The Garnet-actinolite Schists on the Southern Side of the 

 St, Gothard Pass.' By Prof. T. G. Bonney, D.Sc., LL.D., E.K.S., 

 V.P.G.S. 



The author describes the field relations and the microscopic 

 structures of a group of schists or gneisses characterized by the 

 frequent presence of conspicuous garnets and actinolites, which are 

 exposed on the southern slopes of the St. Gothard Pass and for some 

 distance west and east, on the northern side of the Val Bedretto. 

 These, called for purposes of reference the Tremola Schists, he has 

 examined from time to time since 1678, the last occasion being 

 the summer of 1897, when he was accompanied and aided by 

 Mr. John Parkinson, F.G.S. These rocks in the field might be 

 regarded as highly-altered sedimentary strata (as the author once 

 thought) or as a group of igneous rocks (originating possibly in 

 magmatic differentiation) affected by fluxion- movements anterior to 

 consolidation. To the latter view he now inclines, but considers 

 the schistosity and the peculiar minor structures to be the results 

 of crushing (generally without marked shearing) followed by very 

 considerable mineral reconstruction. The garnets he holds to be 

 anterior to this crushing, but the larger biotites and the con- 

 spicuous actinolites to be posterior to it. These minerals, in 

 his opinion, throw some light; on processes of crystallization in 

 rocks more or less pulverized, or, in other words, in the presence of 

 various impediments. He thinks it probable that the Tremola 

 Schists assumed their present form prior to the great Tertiary 

 earth-movements which gave rise to the existing Alpine chain. 



2. " On the Metamorphism of a Series of Grits and Shales in 

 Northern Anglesey.' By C Callaway, M.A., D.Sc, F.G.S. 



These rocks occur in a patch about 3 miles square, situated 

 south-west of Amlwch, and extending from Llanfechell and Rhos- 



