190 Dr. C. R. A.Wright on the Determination of 



The following table gives the average result, in volts*, of 

 upwards of forty series of observations and comparisons, mostly 

 extending over three to four hours, during which time the 

 readings of each particular cell remained sensibly constant: — 



Variation in E.M.F. due to the use of cadmium" 

 and copper sulphate solutions of different 

 strengths, both solutions being of equal I Less than 

 molecular strengths in any given case \ ±'0015. 

 (strengths varying from MS0 4 47H 2 0, to 

 MSO, 1250H 2 'O)t " • • 





Man- Mini- 

 mum, mum. 



Range. Ave " 

 ° rage. 



Effect of substituting for electro-copper : — 

 Amalgamated copper (surface wet with 1 

 liquid mercury) J 



Effect of substituting for bright cadmium : — 



+ •003 



+ •006 

 -•050 



-020 



-•003 



+ •002 

 -•033 



-•005 



006 --001 



•004 +004 

 017 -0415 



015 --015 



Amalgamated cadmium (surface wet with 1 

 liquid mercury . . , J 



Amalgamated cadmium (solid and erys- 1 

 talline) J 



Electromotive force of combinations : — 



Electro-copper — Electro-cadmium 



•756 -750 

 •753 745 



•717 -701 

 •740 -727 



•006 '7525 

 ■008 -7485 



•016 -707 

 •013 ; 7335 



,, ,, Amalgamated cadmium 1 

 (liquid amalgam) J 



,, ,, Amalgamated cadmium 1 

 (solid amalgam) J 





•754 

 •752 



•715 

 ■737 



•749 

 •744 



•701 

 •727 



•005 -7515 

 •008 j -7475 



014 -706 

 010 -7325 





„ „ Amalgamated cadmium "1 

 (liquid amalgam) ...J 



,, „ Amalgamated cadmium 1 

 (solid amalgam) J 



When cells containing bright or electro-cadmium and elec- 

 tro-copper plates were allowed to stand for twelve hours or 



* All the observations given in this paper are reduced to the same 

 standard as that employed in Part V. — viz. the average reading at 15°o 

 of a number of Clark's cells taken as 1-457 volt, the particular Clark's 

 cells used being the same throughout. 



t The specific gravities at about 10° of these fluids are close to the 

 following : — 



MSO^ 47H.O when M is cadmium: spec. grav. 

 do. when M is copper : spec. grav. 



MS0 4 1250 H 2 : in each case below 101. 



1-217. 



: 1*1755 solution 

 nearly saturated. 



