T. Deighton 



•22b 



begins to take effect however the tendency is to concentrate the extra 

 moisture added in the interstices where one particle touches another or 

 the electrode surface and therefore we may expect that the resistance 

 will vary inversely as some function of the moisture content. Experi- 

 mentally it was found to vary approximately as the inverse square of 

 the moisture as had been found iireviouslv bv Whitney. 



COABSt CALCAHEOUS SAN3 



18 19 GO 01 07 03 04 



Log. of % water over hygroscopio 



Fig. 5. 



A tentative explanation of the second series of cases where the 

 particles are covered by a colloid substance was originally elaborated 

 on the theory that the conductivity of a substance in the gel stage would 

 be less than that of the same substance under similar conditions as a sol. 

 Recent work by Miss Laing and Prof. McBainO) however shows that 



the several particles and the electrode the area wetted a:n[(R + AiJ)^ -iJ^] =2ni?. AiJ 

 neglecting higher powers of Ai?. If in is the moisture content nR.\R cctiRm. But for 



any electrode obviously n oc 



1 



Resistance = 



1 



R conductivity area wetted 



experimental results agree with this in the region dealt with. 



oc - . The 



16- 



