Chap. V.] 
WINCHITE. 
157 
Fe203.3Si02, as before leaving the loss on ignition out of account. There 
was then found to be an excess of only 0'03 per cent, of Si02. On this 
interpretation an allowance has to be made in the analyses for a con- 
version of the Fe203 into Fe304 on ignition. The analysis can then 
be restated as follows, on the assumption that the iron is in the form of 
FegOs :- 
SiOo 
. 55-04 
AI2O3 
ro8 
Fe203 
7-06 
MnO 
. 0-77 
MgO 
. 22-00 
CaO 
7 ■ 64 
Na20 
2-80 
K2O 
0-i»8 
Loss on ignition .... 
2-71 
Moisture at 100°C 
. 0-14 
101 00 
— 
be arranged as follows : — 
MgSiOs 
. 55-43 
CaSiOs 
. 15-87 
Na2Si03 
5-70 
KaSiOs 
161 
MnSiOa 
1-42 
Fe203-3Si02 
. 15-03 
A!203-3Si02 
3-OG 
Loss on ignition . . . . 
. 2-71 
Moisture ...... 
. 0-14 
100-97 
Excess Si02 ..... 
. 003 
101-00 
The formula corresponding to this is : — 
14 [(Mg,Ca,Na2,K2,Mn,)Si02] ■^[{Fe,Al)203.3Si02] ; 
or, with all the oxides shown separately, it is : — 
(MgO)53 (CaO)i3 (Na20)4 (KgOh (MnO)x (AloOs)! (Fe203)4 (Si02)89- 
