334 



Scientific Proceedings, Royal Dublin Society. 



In the present investigation the effect of the absorption of water by 

 erinoid upon its electrical resistance was also determined for different times 

 of immersion. This was done as follows. 



The sample in the form of a short tube closed at one end was immersed 

 in water with a length of one cm. projecting above the surface. Mercury 

 was poured inside the tube to a level of that of the outside water, and 

 thermometers reading to 02° C. were placed in the mercury and water. 



The resistance between mercury and water through the walls of the 

 sample was measured for different intervals at ordinary temperature. By 

 warming or cooling the bulbs of the thermometers as required and replacing 

 them in the mercury and water, the temperature of the sample could be 

 adjusted to the right value ; time being allowed to reach a fairly steady state. 

 This operation was done very carefully to avoid wetting the dry part of the 

 tube. An allowance for the evaporation and absorption of the water was also 

 made when necessary. 



The tube was about 6 - 5 cms. long, of outer diameter 2 - 5 cms., and inner 

 diameter 1/55 cms. The results obtained for red and black erinoid are 

 given in Table 1, and Fig. 1 gives the curves relating percentage decrease of 

 resistance and time in hours. 



Table 1. 



Temperature 18 - 6°C. 



Thus the red erinoid has a greater decrease of insulation resistance due to 



