2 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Feb. 1 894, 



Specimens of Cassiterite, Antimonite, Zaratite, and Phacolite, 

 from Victoria, Australia, exhibited by F. Danvers Power, Esq., 

 F.G.S. 



Specimen from Goathurst Common, near Ide Hill, Kent, exhibited 

 by the Rev. R. Ashington Bullen, B.A., F.G.S. 



November 22nd, 1893. 



W. H. Hudleston, Esq., M.A., F.R.S., President, in the Chair. 



George Henry Hill, Esq., M.Inst.C.E., 3 Victoria Street, S.W., 

 and Albert Chambers, Albert Square, Manchester, was elected a 

 Fellow of the Society. 



The List of Donations to the Library was read. 



The Secretary announced that Prof. J. Prestwich, D.C.L., F.R.S., 

 had presented a large framed photograph of himself to the Society. 



The following communications were read : — 



1. 'The Basic Eruptive Pocks of Gran.' By W. C. Brogger, 

 Ord. Prof, of Min. and Geol. in the University of Christiania, 

 For. Memb. Geol. Soc. 



2. ' On the Sequence of Perlitic and Spherulitic Structures (a 

 Rejoinder to Criticism).' By Frank Rutley, Esq., F.G.S. 



3. ' Enclosures of Quartz in Lava of Stromboli, etc., and the 

 Changes in Composition produced by them.' 1 By Prof. H. J. 

 Johnston-Lavis, M.D., F.G.S. 



[Abstract.] 



The Author describes the existence of enclosures of quartz in a 

 lava-stream at the Punta Petrazza on the east side of Stromboli, 

 and also in the rock of the neck of Strombolicchio. He describes the 

 effects of the rocks upon the enclosures, concluding that the quartz 

 has undergone fluxion but not fusion, and has supplied silica to the 

 containing lavas, thus causing an increase in the amount of pyroxene 

 and a diminution in the amount of magnetite in the portions of 

 those lavas that surround the inclusions and raising the percentage 

 of silica. He suggests that such a process at greater depths and 

 higher temperature may, under certain conditions, convert a basic 

 rock into a more acid one, so that possibly the andesite of Strombo- 

 licchio may have been of basaltic character at an earlier period of 

 its progress towards the surface. He offers the suggestion that 

 other rocks or minerals once associated with the quartz have been 

 assimilated by the magma. 



1 This paper has been withdrawn by permission of tbe Council, 



