﻿composition of Herder ite and Beryl. Ill 



beryl analyses, but to select some very pure beryl and 

 make an analysis of it as carefully as possible. The analysis 

 was made according to the method described at the end of 

 this article, and we feel assured from our experience that the 

 results of the analysis represent the composition of the mineral 

 very closely. The beryl which we selected for analysis was a 

 very pure transparent aqua marine from Stoneham, Maine, fur- 

 nished to us by Mr. Greorge F. Kunz of New York. The 

 mineral was crushed and ground in a steel mortar and the 

 fine powder boiled in dilute hydrochloric acid, washed and 

 dried at 100° C. Duplicate analyses were made by both of 

 us, so tiat we might obtain a very fair average. 



Specific gravity taken on a chemical balance, 2 # 706. 



Ratio. 

 SiO„ 65-54 1-092 6- 



A1 2 3 17-75 -172 ) 



Fe 2 O s -_ -21 -001 j 



FeO -38 •005') 



BeO 13-73 -541 



CaO._ -06 -001 



Na 2 -71 -011 J 



Li 2 trace 



HO 2-01 -112 0-61 



173 0-95 



•558 3*06 



100-39 



The ratio of Si0 2 : A1 2 3 : EO : H 2 0=6 : 1 : 3 : 5 nearly. The 

 ratio of the first three is in the proportion required by the 

 usually accepted formula for beryl. This conclusion was also 

 arrived at by Baker* in a recent analysis made according to 

 the same method which we used. As regards the alkalies, we 

 have as yet no proof that they replace the beryllium, but that 

 is probably the case. Analyses of beryls very rich in alkalies 

 would best settle this question. The water is very constant, 

 about two per cent, in all beryls which have come to our 

 notice, with one exception — Aduntschilon, Siberiaf — and must 

 be in some way very firmly united in the molecule, as it is only 

 given off by very strong ignition. As can be seen by our 

 ratio, there is about one-half a molecule present. Beryls 

 which show a higher percentage of water may, and in some 

 cases which have come under our observation do, contain 

 mechanical inclusions of water. Eegarding the water as essen- 

 tial, we would have to add iH 2 to the ordinary accepted 

 formula of beryl, or write it H 2 Be 6 Al 4 Si 12 37 . The theoretical 

 composition according to the above formula is 



* American Chem. Journal, vii, 175. \ This Journal, III, xxviii, 29. 



