OF THE DOUBLE SELENATES OF THE SERIES R2M(Se04)2,6H,0. 
Jorphological Angles of Potassium Magnesium Selenate— continued. 
257 
Angle measured. 
No. of 
measure¬ 
ments. 
Limits. 
I\lean 
observed. 
Calculated. 
Differ¬ 
ence. 
r CO = 001 
111 
0 / 0 ^ 
0 / 
0 / 
34 54 
/ 
op =111 
no 
— 
--■ 
— 
43 34 
— 
J 
cp = 001 
no 
48 
78 20— 78 34 
78 28 
— 
fo' = 110 
111 
— 
-- 
— 
57 13 
— 
o'c = 111 
001 
« - 
— 
— 
44 19 
— 
pc = no 
001 
48 
101 22—101 42 
101 32 
101 32 
0 
^ho = 010 
111 
_ 
69 57 
< 
[os = 111 
101 
— 
— 
— 
20 3 
_ i 
\ho = 010 
Ill 
_ 
' 
_ 
65 16 
' 
[oV = 111 
loi 
— 
■ — 
— 
24 44 
— 
Csq^ =101 
on 
_ 
_ 
_ 
38 19 
_ 
qp = on 
no 
13 
85 26— 85 46 
85 35 
85 34 
1 i 
i 
ps, = no 
loi 
— 
--- 
— 
56 7 
1 
jpq^ = no 
oil 
13 
94 12— 94 40 
94 25 
94 26 
1 
r.s7 = 101 
on 
_ _ 
_ 
_ 
44 55 
_ 
qp =011 
no 
14 
64 0— 64 15 
64 7 
64 5 
2 
i 
ps = no 
101 
— 
— 
— 
71 0 
— 
J)q = 110 
oil 
14 
115 45 — 116 5 
115 53 
115 55 
2 
r r'o' = 201 
Ill 
__ 
34 30 
J 
o'p =111 
no 
— 
— 
— 
92 54 
— 
i 
pr’ = 110 
201 
28 
.52 21 _ 52 42 
52 33 
52 36 
3 
Ir'p = 201 
no 
28 
127 18—127 37 
127 27 
127 24 
3 
Total number of measurements, 324. 
From measurements made by Topsoe in 1870, Topsoe and Christiansen (/oc. cd., 
p. 75) quote for the ratio of the axes and the axial angle u\h -.c — 07447 : 1 : 0'5014, 
and /3 = 75° 43'. 
The cleavage direction common to the series, namely, parallel to r [201}, is well 
developed. 
Volume. 
Relative density. —The following four determinations were carried out with difierent 
specimens of the salt:— 
"Weight of salt 
employed. 
7-4818 
6- 2738 
7- 1272 
6-2631 
2 L 
Sp. gr. at 
2074°. 
2-3627 ^ 
2-3630 
2-3634 , 
2-3630 J 
i- Mean, 2-3630 
VOL. exeVIL—A. 
