MINKUALiMIICAl, NoTKS ANl>KI(SON. 31 



pvi'D-arseuate. The Hlti-ate t'roui sulpliidt' of ai-sunic was evaporated, 

 rendered ;ilkaliiie with ammonia, nnd pliosjdioric ncxd precipitated l)y 

 magnesia mixtuie. Chlorine was determined in another portion weighinp^ 

 •!)5l>5 gram, whicli was dissolved in niti'ic aeid and pieeipitated with 

 silver nitrate. The result Avas as follows : — 



Pb 7(vV2 



As.^0, -io-r^r) 



i\o, i-n 



Cf 2-00 



100-ly 



Less oxygen eqaivaleut to 



ehloriue ... ... '-tr) 



yy-7o 



In conclusion, I have to record my indebtedness to Messrs. 

 W. T. Watkin BroAvu, U. A. Porter and G. Smith for the loan of 

 specimens, and to Messrs. B. J. Smart, B.Sc, and H. K. M. Curry, of 

 the Testing Brauch, Departmeut of Public Works, through whose kiud 

 offices the artificially etched ciystal of beryl was photographed. 



