SPECIFIC INDUCTIVE CAPACITY OE DIELECTRICS. 
579 
paraffine was poured to a depth of about one centimetre. Upon this, when solid, a 
piece of brass tubing 4 - 3 centimetres long and 7 - 24 centimetres in internal, and 
7*47 in external diameter, was rested so as to he concentric with the outer tube. Inside 
of this, and concentric with it, was placed another piece of brass tubing (c c), 13T centi- 
metres long and GT centimetres in external diameter. The space between this and the 
outer tube was then filled with paraffine, and from the middle tube thus imbedded a fine 
wire electrode ( d cl) was carried up. The condenser was put into a vessel containing 
water in which was placed a thermometer; and another thermometer {ee) was supported 
in the centre of the inner tube by a paraffine plug (ff) about a centimetre thick, which 
rested upon the top of this tube. This plug prevented the communication downwards 
of the temperature of the air. As an additional security, another paraffine plug (g g) 
of the same thickness was inserted in the inner tube a little above the bulb of the ther- 
mometer. 
The outer and inner tubes were connected with the earth, and the electrode from the 
other tube, which was insulated, was connected with the one side of the platymeter. 
An addition to the capacity of the sliding condenser had been made, increasing its 
zero-value, so that the readings for the spherical condenser were : 
Date. 
a. 
p. 
a +/3 
2 * 
Dec. 13, 1 C 69 
28 
2 
15 
This gives for the zero-value of the sliding condenser 1572 — 15 = 1557 scale-divisions. 
With this value the results shown in the following Table were obtained for the value 
of the cylindrical paraffine condenser at different temperatures. 
Date. 
Temperature. 
Condenser Scale. 
Value. 
Outside. 
Inside. 
Mean. 
CL . 
a-f/3 
2 ‘ 
Dec. 22, 1869 
O 
7-5 
O 
7-5 
7 '5 
158 
145 
1702 
Dec. 22, 1869 
17-6 
17*6 
1 7'6 
1 58 
1 45 
1702 
Dec. 29, 1869 
2-7 
2-7 
2-7 
150 
137 
1694 
Dec. 30, 1869.. 
5-7 
5-7 
5-7 
147 
134 
1691 
Dec. 30, 1869 
15-4 
15-7 
1 5*55 
145 
132 
1689 
Without the addition to the value of the sliding condenser the following measure- 
ments of the spherical condenser were taken : — 
Date. 
i«- 
p- 
«+/3 
•> • 
Dec. 10, 1869 
202 
176 
189 
Jan. 5, 1870 
201 
188 
Jan. 7, 1870 
200 
187 
Jan. 8, 1870 
199 
186 
Jan. 12, 1870 
201 
188 
Jan. 17, 1870 
202 
189 
Jan. 17, 1870 
202 
173 
18/ 
4 L 
MDCCCLXXI. 
