152 Proceedings of the Royal Society of Edinburgh. [Sess. 
64 Groups 
No. 
Formula. 
Si0 2 . 
Ti0 2 . 
PA- 
H 2 0. 
A1 2 0 3 . 
Fe 2 0 3 . 
FeO. 
52 
b b 
a a b b 
42-2 
2-1 
2-3 
13*2 
8 4 
11*2 
53 
b b 
a b a a 
46*5 
1-6 
•3 
2*6 
14-0 
5-4 
63 
54 
b b 
a b a b 
44*6 
1-0 
•4 
1-4 
16*3 
5-7 
6-8 
55 
b b 
abba 
44*7 
•9 
•3 
1-5 
16-6 
7-0 
7-8 
56 
b b 
a b b b 
42*2 
•2 
•1 
1*8 
17-9 
8-3 
8-1 
57 
b b 
b a a a 
45*7 
•2 
3-5 
4-3 
3-9 
7-6 
58 
b b 
b a a b 
42*0 
1-3 
2-6 
3-0 
7-7 
59 
b b 
baba 
41*6 
•4 
•1 
4*7 
9-2 
5'5 
8-0 
60 
b b 
b a b b 
37-0 
•2 
4‘3 
4-9 
7-8 
11-8 
61 
b b 
b b a a 
46*7 
•7 
•2 
1*9 
11-3 
3-4 
5*7 
62 
b b 
b b a b 
42-2 
1*5 
•2 
1-9 
12-0 
4 3 
6-1 ! 
I 63 
b b 
b b b a 
41-9 
1-3 
•4 
2-4 
11*7 
7*3 
6-4 
64 
b b 
b b b b 
39-5 
1*3 
•5 
2*2 
13-5 
7-7 
7-0 
| 
57-4 
•5 
*2 
1*8 
15-6 
37 
4-0 
