22 
DR. A. E. H. TUTTON ON THE 
Table of Molecular Refraction and Dispersion (Lorenz). 
Salt. 
Molecular refractic 
n 2 - 1 
M 
A = m - 
Molecular dispersion. 
m G - m c . 
’ n 2 + 2 
For ray C (H a)- 
For ray Ely near G. 
a. 
ft. 
y- 
CL. 
ft- 
7- 
CL. 
ft. 
7- 
KCo sulphate 
55-43 
56-00 
57-33 
56-61 
57-17 
58-57 
1-18 
1-17 
1-24 
RbCo 
58-63 
59-20 
60-19 
59-83 
60-41 
61-48 
1-20 
1-21 
1-29 
AmCo 
59-43 
59-95 
60-77 
60-89 
61-40 
62-22 
1-46 
1-45 
1-45 
CsCo 
64-50 
64-81 
65-30 
65-87 
66-18 
66-71 
1-37 
1-37 
1-41 
Molecular Refraction (Gladstone and Dale). 
n ^ M for ray C. 
cl J 
Mean molecular 
Salt. 
refraction for ray C. 
i (cc + ft + y). 
a. 
ft- 
7 - 
KCo sulphate. 
93-61 
94-75 
97 • 35 
95-24 
RbCo ,,. 
• 99-17 
100-32 
102-29 
100-59 
AmCo ,,. 
100-64 
101-70 
103-33 
101-89 
CsCo ,,. 
109-75 
110-39 
111-37 
110-50 
Optic Axial Angle ,—-The results with three pairs of section-plates perpendicular 
to the first and second median lines are given in the two next tables. The angle in 
air, although very large, was just clearly visible in all three of the plates ground 
perpendicular to the first median line, but the absorption at the blue end of the 
spectrum prevented trustworthy observations being obtained beyond the wave-length 
of T1 light. 
Apparent Optic Axial Angle in Air, 2E, of AmCo Sulphate. 
Light. 
Plate 1. 
Plate 2. 
Plate 3. 
Mean 2E. 
Li. 
o / 
156 1 
157 34 
o / 
155 16 
o / 
156 17 
C. 
156 20 
157 51 
155 34 
156 35 
Na. 
158 32 
159 52 
157 29 
158 38 
T1. 
160 40 
162 0 
159 40 
160 47 
A determiuation of 2E at 70° with Plate 1 gave the value 153° 5' for sodium light, 
indicating that the optic axial angle in air diminishes with rise of temperature to 
the extent of 5|-° for 55° of rise. 
