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LIV.— ANALYSIS OF THE BERYLS OF GLENCITLLEN, CO. 

 "WICKLOW. By f . K HARTLEY, F.R.S., Royal College 

 of Science, Dublin. 



[Read, March 23, 1887]. 



The beryls of Glencullen, Co. Dublin, described by Professor 

 J. P. O'Reilly, 1 and by Mr. J. Joly, B.E., 2 were analysed about 

 twelve months since by Mr. J. B. Wise, a student in the Eoyal 

 College of Science. 



Analysis. — One grain of the mineral was fused with six parts 

 of mixed potassium and sodium carbonates. After treatment with 

 acids, it was found that a small portion of the substance remained 

 unattacked. This was again fused, and it then showed a very 

 decided green colour characteristic of manganese, possibly derived 

 from the iolite contained in the mineral. The following are the 

 data : — 



Analysis I. Analysis II. 



Ordinary Crystals. "Weathered" Crystals. 

 Per Cent. Per Cent. 



Si0 2 47-47 54-27 



A1 2 3 32-49 27-23 



BeO 11-29 10-50 



CaO 2-60 1-40 



FeO 3-13 2-88 



MgO 0-41 0-47 



Na 2 0-46 0-47 



K 2 0-62 0-41 



MnO trace. 



H 2 0-48 Not estimated. 



98-95 97-63 



Bases = 51-01 Bases = 43-36 



Silica = 47-47 Silica = 54-27 



The specific gravity of the specimens represented by Analysis I. 

 is 2-706 at 15-2° C. 



1 Proceedings, E.B.S., vol. iv., p. 505. 

 3 Proceedings, S.D.S., antea, p. 48. 



