CAPACITY AND BESIDUAL CHARGE OP DIELECTEICS. 
135 
was made introducing a suitable compensating leakage into one of the other 
condensers of the bridge/^ The result indicated a capacity between 50- and GO. 
Water. 
The platinum plates (fig. 2) were placed in ordinary distilled water in a beaker 
which was cooled to 0° C. by a surrounding brine solution composed of water, common 
salt and ice. The experiments with the short-contact apparatus show no material 
difference in the apparent resistance, whether the time of contact be "00002 or 
•00099 second; the apparent resistance for these times is 379 ohms. The effects of 
residual charge in water do not affect the resistance within the range of times of 
contact given by this apparatus. 
[Added March 17th, 1897.] 
Oil of Lavender. 
This oil was supplied by Messrs. Hopkin and Williams : it was tested with the 
short-contact apparatus, fig. 5, = ’33, = *0015 microfarad. The charging 
potential was 1250 volts ; the following figures give the results :— 
Time of contact in seconds . . ‘00002 *00099 ’0028 '006 '01 
«in ohms. 9500 14000 14500 14800 14800 
The high frequency resonance experiments give specific capacity 3'89 : the 
frequency being of the order 2 X 10®. 
Two experiments were made at low frequency. First, the Bridge method, fig. 3, 
which gives the following results, the temperature of the oil being 16°C. :— 
Frequency Charging Specific. 
Volts. 
Capacity. 
18 
65 
5'6 
79 
30 
4-,34 
Second, the Bridge method with Ruhmkorff coil as used in the castor oil experi¬ 
ments. Temperature 14°C. Specific capacity 4*18. 
Experiments have been made by Stankewitsch (‘ Wied. Ann.,’ 52), showing a 
variable capacity for oil of lavender. We, however, have not succeeded in obtaining 
any result so high as his. 
* This appears to have been done bj Nernst, ‘ Physical Society’s Abstracts,’ vol. 1, p. 38. 
