SPECIFIC INDUCTIVE CAPACITY OE DIELECTBICS. 
581 
altogether 6 G ' 9 S 3 grammes. The following Table shows the results of the weighings 
in water. The weights are given in grammes, and the volumes in cubic centimetres. 
Temperature. 
Weight of paraffine 
and platinum in 
water. 
Weight of water 
displaced by both. 
Volume of both. 
Volume of 
platinum. 
Volume of 
paraffine. 
0 
1 
3-698 
53-285 
53-289 
•4077 
52-881 
8-8 
3-413 
53-570 
53-579 
•4078 
53-171 
10-1 
3-372 
53-611 
53-626 
•4078 
53-218 
17-2 
3-139 
53-844 
53-909 
•4079 
53-501 
These numbers give for the expansion of paraffine the results shown in the following 
Table* : — 
Temperature. 
Difference 
of volume. 
Mean 
volume. 
Total 
expansion. 
Cubic expan- 
sion per 
degree. 
Linear ex- 
pansion per 
degree. 
Mean 
temperature. 
Prom 
To 
Diff. 
0 
1 
O 
8-8 
7'8 
•290 
53-026 
•00547 
•000701 
•000234 
O 
4-9 
1 
10-1 
9-1 
•337 
53-049 
•00635 
•000698 
•000233 
5-55 
1 
17*2 
16-2 
•620 
53-191 
•01166 
•000720 
•000240 
9-1 
8-8 
10-1 
1-3 
•047 
53-195 
•00088 
•000677 
•000226 
9-45 
8-8 
17-2 
8-4 
•330 
53-336 
•00619 
•000737 
•000246 
13 
10-1 
17-2 
7-1 
•283 
53-360 
•00530 
•000746 
•000249 
13-65 
From these determinations of the expansion of paraffine the effect produced by variations 
of temperature upon the capacity of the tinfoil condenser may be easily calculated. 
The mean value of the condenser 1638 - 5 scale-divisions maybe taken as its value at the 
mean temperature 13 0, 7. Its values at the different temperatures estimated from this, 
together with those previously given as obtained from actual measurements, are shown 
in the following Table : — 
Temperature. 
Measured value. 
Estimated value. 
O 
7*2 
1642 
1641 
11-4 
1640 
1639-4 
14-5 
1638 
1638-2 
21-8 
1634 
1635-1 
The values given in the last column of this Table were estimated on the supposition 
that the expansion of the paraffine did not produce any sensible stretching of the tinfoil ; 
and this, from the manner in which the condenser was formed, was probably the case. 
From this it appears that the regular alteration in the values obtained for this condenser 
at different temperatures follows so nearly that resulting from the variations of the 
* After these experiments were made it was found that the French “ Bureau des Longitudes/’ in the { An- 
nuaire’ for 1870 published by them, give, on the authority of M. Fizeatj, -00027854 per degree Centigrade as 
the coefficient at 40° Centigrade of linear expansion of “ paraffine de Rangoon, ” and -0000009926 as the “ varia- 
tion of coefficient” per degree. This gives -00024787 as the expansion per degree at temperature 9°-l, that 
given in the Table at the same temperature being -000240. 
4 L 2 
