MONOCLINIC DOUBLE SULPHATES CONTAINING AMMONIUM. 
43 
Table of Molecular Refraction and Dispersion (Lorenz). 
Salt. 
Molecular refractio 
71 s - 1 
M 
- = in. 
Molecular dispersion, 
m G - m c . 
’ n 2 + 2 ' 
For ray C (Ha). 
For ray Hy near G. 
cl. 
A 
7 - 
CL. 
A 
7 - 
GL. 
A 
7 - 
KCu sulphate 
55 • 93 
56-20 
57-73 
57-24 
57 • 55 
59-09 
1-31 
1-35 
1-36 
RbCu ,, 
59 • 23 
59-44 
60-77 
60-57 
60-79 
62-17 
1-34 
1-35 
1-40 
AmCu ,, 
59-41 
60-38 
60-87 
60-86 
61-85 
62 • 35 
1-45 
1-47 
1-48 
CsCu „ 
64-53 
64-70 
65-67 
66-02 
66-19 
67-18 
1-49 
1-49 
1-51 
Molecular Refraction (Gladstone and Dale). 
Salt. 
CL. 
'—j— M f° r ray C 
. A 
7 - 
Mean molecular 
refraction for ray C. 
r (« + /3 + y). 
KCu sulphate. 
94-53 
95 • 06 
98-13 
95-91 
EbCu ,, . 
100-27 
100-69 
103-35 
101-44 
AmCu ,, ..... 
100-63 
102-57 
103-56 
102-25 
CsCu „ . 
109-78 
110-11 
112-07 
110-65 
As regards the important property of molecular refraction the copper group shows 
the same relation as the other groups, namely, that the values for the ammonium 
salt are slightly higher than those for the rubidium salt, as is well expressed in the 
last column of the third table by the mean molecular refraction. 
Optic Axial Angle .—Three pairs of section plates, parallel to the first and second 
median lines, afforded the following results :— 
Apparent Optic Axial Angle in Air, 2E, of AmCu Sulphate. 
Light. 
Plate 1. 
Plate 2. 
Plate 3. 
Mean 2E. 
Li ... . 
116 41 
o / 
115 45 
o / 
116 20 
o / 
116 15 
C. 
116 20 
115 27 
116 0 
115 56 
Na. . . 
115 18 
113 43 
114 46 . 
114 36 
T1 . . . 
114 19 
112 50 
113 40 
113 36 
Cd. 
113 32 
112 0 
113 9 
112 54 
F. 
113 12 
111 30 
112 45 
112 29 
G 2 
