CAPACITY OP GLASS, AND OP LIQUIDS. 
373 
index for long waves was calculated by the formula «+ The results are given in 
the following table :— 
h C. 
rD. 
#*P. 
pG. 
fJ. 00. 
Tempei ature. 
Petroleum spirit. 
1-3952 
1-3974 
1-4024 
1-4065 
1-3865 
12-75 
Petroleum oil (Field’s) . 
1-4520 
1-4547 
1-4614 
1 4670 
1-4406 
13-0 
Petroleum oil (common) 
1 -4525 
1-4551 
1-4615 
L4670 
1-4416 
13-0 
Ozokerit lubricating oil. 
1-4558 
1-4585 
1-4653 
1-4443 
13-0 
Turpentine. 
1-4709 
1-4738 
1-4811 
1-4871 
P4586 
13-25 
Castor oil. 
1-4785 
1-4811 
1-4877 
1-4931 
1-4674 
13-5 
Sperm oil. 
1-4724 
1-4749 
1-4818 
1-4611 
13-75 
Olive oil. 
1-4710 
1-4737 
1-4803 
1-4598 
14-0 
Neatsfoot oil. 
1-4673 
1 4696 
1-4578 
14-0 
In the following table is given a synoptic view of the comparison of /ico 2 and K 
fJ. GO. 
fjL GO 2 . 
K. 
Petroleum spirit. 
1-3865 
1-922 
1-92 
Petroleum oil (Field’s). 
.L4406 
2-075 
2-07 
Petroleum oil (common) . 
1-4416 
2-078 
2-10 
Ozokerit lubricating oil . 
1-4443 
2-086 
213 
Turpentine. 
1-4586 
2-128 
2-23 
Castor oil. 
1-4674 
2-158 
4-78 
Sperm oil. 
1-4611 
2-135 
3-02 
Olive oil. 
1-4598 
2-131 
3-16 
| Neatsfoot oil. 
1-4578 
2-125 
3-07 
A glance shows that vegetable and animal oils do not agree with Maxwell’s theory, 
the hydrocarbon oils do. It must, however, never be forgotten that the time of 
disturbance in the actual optical experiment is many thousands of million times as 
short as in the fastest electrical experiment even when the condenser is charged or 
discharged for only the 2 0 q q-q second. 
c 2 
