42 



alcalies were separated from one another by chloride of platinum, and 

 the water was determined by ignition. Its composition is as follows : 



Silica 57.69 



Lime 26.83 



"Water 14.71 



Soda .44 



Potash .23 



Oxide of Iron - - - - .32 



Oxide of Manganese - - .22 



100.44 



' This composition differs from that of all other minerals, so far as 

 the author's knowledge extends; and shows the sulDstance under 

 analysis to be a hydrated quatersilicate of lime, conformably to the 

 formula, 9 S* C + 16 Aq. 



Sir David Brewster, who possesses a mass of the mineral which he 

 received froni Count Vargas Bedemar, has observed crystallized faces, 

 but so near the general surface, that they cannot be separated. He 

 has also found that it possesses double refraction ; that it reflects a 

 bluish light, and consequently transmits a yellowish one ; and that 

 it possesses no pyroelectricity. He has no doubt that it is a new 

 mineral. 



The author proposes to distinguish it by the name of Dysclasite, 

 [Svs kAow], as expressive of its remarkable tenacity and difficult fran- 

 gibility. It will, of course, be arranged with the Zeolites. 



The Secretary read an extract from a letter, giving a short descrip- 

 tion of the Stalactitic Caves recently discovered in the county of 

 Tipperary, and exhibited various illustrative drawings. 



Several additional s^jecimens were exhibited from Burdiehouse 

 Quarry ; and Dr Hibbert read a short notice relative to the position 

 of the limestone there, and the relation it bears to the mountain- 

 limestone of Muirhouse and the neighbourhood. His observations 

 were to the effect that, by examining some sections of the strata be- 

 tween Burdiehouse and Loanhead, he had now satisfied himself that 

 the limestone of Burdiehouse lies beneath the great bed of mountain 

 limestone fonnerly described by him as traversing the country from 

 Joppa towards the Pentland Hills. The order of the strata between 

 them is as follows : — Burdiehouse limestoiie — shale and thin beds of 

 the same limestone, — sandstone and shale, — sandstone, coal blaes, 

 ironstone bands, and thin seams of coal — Mountain limestone — lime- 

 stone blaes — Coal measures. 



i 



