Penfield and Sperry — Mineralogical Notes. 319 







Measured. 



Calculated. 



No. of times. 



Limit. 



V •, V 



3121 ,s 2131 



31° 34' 



31° 46' 



4 



30° 57'-31° 34' 



V ~ V 



2131^1231 



18° 31' 



18° 11' 



4 



18° 31'-19° 51' 



Jc^Jc 



6241 ~ 4.261 



36° 28' 



37° 14' 



2 



35° 8'-36° 28' 



h A.k 



4261 ^ 2461 



20° 40' 



20° 41' 



2 



20= 2'-20° 41' 



*a£ 



4261^3361 



10° 36' 



10° 21' 



2 



9° 32'-10° 36' 



m a.v 



1010 a 3121 



37° 25' 



37° 49' 



2 



37° 16'-37° 25' 



m ~n 



1010^4131 



28° 51' 



29° 0' 



1 





m ^ Jc 



1010^6241 



25° approx. 



26° 8' 



1 





m^m 



1010 a 0110 



59° 49' 



60° 3' 



1 





v -.Tc 



3121^6241 



15° approx. 



15° 6' 



1 





The results of the chemical analyses of the three varieties are 

 as follows : 



I. Norway, Maine, Sp. Gr. 2-747, 



II. Litchfield Co., Ct., Sp. Gr. 2*716. 



III. Willimantic, Ct., Sp. Gr. 2-725, 



No. 409A in Professor Brash's collection. 



No. 410 A in Professor Brash's collection. 



Si0 2 



A1 2 3 



Fe 2 3 



FeO 



MnO 



BeO 



Cs 2 



K 2 



Na 2 



Li 2 



Ign 



64-12 

 17-89 



•16 



12-13 



1-61 



•10 



1-21 



•75 

 2-24 



Ratio. 



1-069 



•175 



•002 



•485 

 •007 

 •001 

 •029 

 •015 

 •124 



100-21 



The ratios are as follows : 



Si0 2 : A1 2 3 : RO : 



I 1-069 -175 -539 



II 1093 -177 -554 



III 1-095 -180 -551 



II. 



65-62 



17-86 



•37 



•18 



13-50 

 •03 



•54 



•10 



2'34 



100 54 



Ratio. 



1-093 

 •175 

 •002 

 •002 



•540 



•009 

 •003 

 •130 



III. 

 6572 

 18-40 



•26 



•12 



13-08 



•12 



•75 



•28 



2-06 



100-79 



Ratio. 



1-095 



■180 



•004 

 •002 

 •523 



•001 

 •012 

 •009 

 •114 



H 2 0. 

 •124 

 •130 

 •114 



0-98 

 0-97 



0-98 



3-03 

 3-04 

 3-02 



0-70 

 0-71 

 0-62 



In the above ratios, RO includes all the protoxides (Be, Fe, 

 Mn, Cs 2 , K 2 , Na„ Li„)0. In relation to the alkalies, it will be 

 seen that in analysis I, the BeO is fully one per cent lower 

 than in II and III, while by a consideration of the ratios it 

 will be seen that this deficiency is fully made up by the pres- 

 ence of a sufficient quantity of alkalies. This is certainly the 

 necessary proof of the correctness of our assumption that the 

 alkalies in beryl are isomorphous with the BeO. In analysis 

 I, if we neglect the alkalies, the ratio of Si0 2 : A1 2 3 : BeO be- 

 comes 6: 0*98: 2*72. In analysis II there is an unusual quan- 

 tity of Fe 2 3 , which may account for the yellow color of the 

 beryl ; however, the results of the FeO and Fe 2 3 determina- 

 tions can not be regarded as very exact, owing to the difficulty 

 of decomposing the beryl with hydrofluoric acid, though special 

 care was taken to make the determination as exact as possible. 

 Aside from the above-mentioned peculiarities, the analyses 



