26o 



SDLSBEE AND HONAMAN: CONDUCTIVITY MEASUREMENTS 



polarizing test, and on the following day, respectively. The 

 apparent permanent increase of resistance observed with this 

 specimen serves to explain some mysterious results obtained at an 

 earher date, in which one specimen had shown an increase of 

 resistance to more than twenty times its initial value | after 



FJg- 3- Variation in resistance of glass cup resulting from polarization. 



several successive tests. The fact that an appreciable time is 

 required to obtain a reading, even with quick acting direct cur- 

 rent indicating instruments, and that during this time the speci- 

 men is being polarized, is probably a complete explanation of the 

 variation of apparent resistance with appUed voltage. If the 



