54G 



Mr. A. G-ilmour on the Resistance of 



within the scale of the instrument, and the resistance R 

 could again be calculated, knowing the deflexion and 

 voltage applied. The sensitivity of the galvanometer was 

 about l/HxlO -8 amp. per mm. scale-division, and was 

 tested at the beginning and end of each set of readings to 

 ensure that it remained constant during the experiment. 



To get the specific resistance factor of the cell, the latter 

 was filled with clean mercury and the resistance measured. 

 The specific resistance of mercury divided by this measured 

 resistance gives the factor of multiplication which transforms 

 the actual resistance of any liquid in the cell into the specific 

 resistance in ohms per c.c. 



Solutions. 



Owing to the difficulty of obtaining drainage of the 

 glycerine from burettes and measuring-vessels, the com- 

 position of the solution is expressed in grams of copper 

 sulphate per gram of glycerine. Blue crystallized copper 

 sulphate CuS0 4 , 5H 2 was used. The required weight of 

 it was added to a known weight of glycerine, and the whole 

 heated slightly until the copper sulphate dissolved. The 

 resistances were measured while the solutions were fresh. 



Results. 



The results are given in the following table and are 

 represented in Curves I, II, III. It will be seen that when 

 the concentration of the copper sulphate (as measured by 

 the scale of numbers used as abscissae) lies between -01 and 



Gms. CuS0 4 

 added to 



lgm. 

 glycerine. 



Sp. Res. 



10 4 



in 

 ohms/cc. 



Gms. OnS0 4 

 added to 



1 gm. 

 glycerine. 



Sp. Res. 



10 4 

 in 



ohms/cc. 



Gms. CuS0 4 

 added to 



1 gm. 

 glycerine. 



Sp. Res. 



104 



in 

 ohms/cc. 







441 



•0102 



39-4 



•0338 



7-91 



•0010 



245 



•0110 



410 



•0400 



5-93 



•0022 



153-7 



•0130 



344 



•0474 



5-52 



•0033 



119-0 



•0140 



20-5 



•0691 



470 



•0040 



91-9 



•0170 



21-2 



•1004 



3-40 



•0060 



64-8 



•0200 



23-0 



•1291 



2-50 



•0070 



52*5 



•0230 



16-2 



•1683 



1-36 



•0086 



40-1 



•0254 



8-78 



•2008 



1-20 



•0095 



31-5 



•0285 



9-05 



•2584 



1-08 



•03, maxima and minima occur in the curve. From the 

 positions of the points in the vicinity of the first maximum 

 it seems possible that subsidiary peaks are there present, 

 but no close investigation has been made of these, as this 



