﻿British Mineralogy. 331 



3-68 



10-57 



99-89 4044 

 Upon calculation it will be found (when the smaller amounts 

 of alumina, protoxide of manganese, and magnesia are taken into 

 consideration, along with respectively the sesquioxide of iron, 

 protoxide of iron, and lime) that we have 12 equivalents of silica, 

 1 of sesquioxide of iron, 3 of protoxide of iron, and 6 of lime ; 

 and taking the atomic numbers of these substances at SiO 2 = 30, 







Oxygen. 



Silica 



. 49-12 



26-19 



Alumina 



. 1-60 



0-751 



Sesquioxide of iron . 



. 9-78 



293 J 



Protoxide of iron 



. 12-87 



2-86] 



Protoxide of manganese 



1-25 



028 1 



Lime 



. 20-87 



5-96 f 



Magnesia 



. 3-67 



1-47J 



Loss on ignition . 



. 0-73 





3 = 



= 80, 



FeO = 36, 



andCaO: 



= 28, we 



should have 







12Si0 2 . 



• • • 



360 



50-28 







lFe 2 3 



. • • 



80 



11-17 







3FeO . 



... 



108 



15-08 







6CaO . 



. . . 



168 

 716 



23-47 

 100-00 



These numbers, which approximate closely to those found by 

 actual analysis as above stated, indicate the mineral to be com- 

 posed of 



6 CaO SiO 2 + 3 FeO SiO 2 + Fe 2 O 3 SiO 2 , 



or 9(CaFe)0, Si0 2 -f Fe 2 O 8 SiO 2 , 



giving the general formula 



9ROSi0 2 + R 2 3 , SSiO 2 , 

 in which the protoxides are those of iron, manganese, lime, and 

 magnesia, whilst the sesquioxides are alumina and sesquioxide 

 of iron. 



In the analysis of the Babingtonite from Arendal, spec. grav. 

 3*366, Rammelsberg * obtained thefollo wing percentage results: — 



Oxvgen. 

 Silica 51-22 



Sesquioxide of iron . 

 Protoxide of iron . 

 Protoxide of manganese 

 Lime 



Magnesia . 

 Ignition loss 



11-00 

 10-26 



791 

 1932 



0-77 



0-44 



i0(>92 

 Handbuch der Miner alchemie, p. 4/7 



