398 Geological Society. 



Lustre shining, silky on the fibrous face; dull on that of 

 the laminae. Transparency of the laminae 0, fibres translu- 

 cent. Colour pale greenish gray ; extei'nally yellowish, from 

 adhering sulphur. Taste slightly acid and astringent; i7i- 

 odorous. 



Solubility. In cold water little or none ; but the fibres fall 

 asunder : on applying heat, the colour changes to orange, and 

 the hot water dissolves a portion, acquiring its taste. In mu- 

 riatic acid swells like sponge, assuming a rich orange colour, 

 and soon dissolves, except a little residue of sulphur and earth. 

 By dry heat, in tube closed at one end, the fibres separate 

 and become orange-coloured, giving off much water and a 

 little sulphur : by increased heat, sulphuric acid is driven off, 

 and the residue left red. In open tube, much the same : on 

 charcoal, before the blowpipe, exhales the odour of sulphur ; 

 and shrinks exceedingly, leaving a residue of oxide of iron. 

 By analysis, Oxygen. 



Peroxide of iron 31 = 9'5 



Sulphuric acid 26 = 15*5 



Water 33 = 29- 



Sulphur, earth and loss 10 



100 



the acid containing 1 '5, and the water three times the oxygen 

 of the base, formula 2 Fe2 O3 + 3 S O3 + 18 Aq, containing 

 half as much acid as the persulphate of iron, and a little ex- 

 cess, to which the sapidity is probably due. 



Its aspect and composition suggest the name Fibrofen'ite. 



J. Prideaux. 



LXI V. Proceedings of Learned Societies. 



GEOLOGICAL SOCIETY. 

 May 27, — npHE memoir " On the Classification and Distribution 



1840. X of the Older Rocks of tlie Nortli of Germany," &c., 

 by Prof. Sedgwick and Mr. Murchison, commenced at the previous 

 meeting, was concluded*. 



In an introduction of considerable length, the authors enter on a 

 historical review of the different steps by which they had been led, 

 during the former year, to place nearly all the older slates of Devon- 

 shire, and a considerable part of the slate rocks of Cornwall, in a 

 group intermediate between the carboniferous and Silurian systems, 

 and therefore coeval witli the old red sandstone of Herefordshire. 

 To the vast group of slate rocks, so defined, they proposed the name 

 of Devonian System ; and their leading object in visiting Belgium, 

 the Rhenish provinces, the Hartz, &c., was to ascertain whether in 

 any of those countries there was a group of strata (no matter of what 

 mineralogical character) with Devonian fossils, and in a position 



* See L. E. and D. Phil. Mag., vol. xvii. p. 508.— Edit. 



