4:96 



Dr. H. H. Poole on the Electrical 



specimen is somewhat higher. No simple general equation 

 has been found connecting: the various isotherms. 



Fiar. 4. 



Leg K 







/S 







/ s 





f 



W x 



y / 



°Sy 



•O/ 



/ / 



/ / 



/ / ° 



/ ' 



- / - -. ... / 



/ 

 V 



i 

 1 



! 



Mica Specimen B 



Glass. 



Tests were carried out on glass specimens, very thin 

 microscope cover-glasses, 5 cm. square, being used. The 

 faces were silvered, and the silvering then removed with a 

 pointed piece of soft wood moistened with very dilute nitric 

 acid, leaving a circular patch of suitable size in the centre of 

 each. A circle was dra\wi on one of these patches with a 

 sharp style, an optical arrangement being used as a guide. 

 This isolated a central region which was connected to the 

 galvanometer, the surrounding annular silvering forming an 



