120 Messrs. Wright and Thompson on the Determination of 
II. Cadmium. 
189. Cells were set up with electro-cadmium plates im- 
mersed in cadmium-nitrate solution, opposed on the one hand 
to electro-copper, and on the other to amalgamated zinc im- 
mersed in solutions of their nitrates respectively, the constant 
solution-strength being :25 M(NO3;).100 H,O. The following 
values were obtained :— 
Zine-Cadmium. | Cadmium-Copper. 
$< 
Maximum ......... B59 £722 
Minimum ......... "344 ‘707 
Average ......scece "351 ‘713 
Probable error ... +:0026 +:0024 
From these figures the following valuations result for the 
voltaic constant of cadmium in nitrate solution ‘25 Cd(NO3), 
100 H,0:— 
Aincscadminm: i... "sis “e) pelinel hs, ciel. al | 
Zinc-copper—Cadmium-copper. . 1:066—‘713 =°353 
Mean .° i0: 9 t=saa2 
Julius Thomsen finds Cd, O, N,O; aq. = 86300 (for 
‘25 Cd(NO3), 100H.O), whence Hy="357. Hence the thermo- 
voltaic constant for electro-cadmium in nitrate solution of 
this strength is 
K—Ey='352 —°357= —:005. 
It is here noticeable that the value of the thermovoltaic 
constant is negative, as in the case of chloride solution of 
corresponding strength, whereas it is positive in the case of 
sulphate solution of the same strength; but in no case is the 
numerical value of the constant large. 
Ill. Lead. 
190. Cells containing electro-lead opposed to amalgamated 
zinc and electro-copper in nitrate solution of strength 
mM (NO3;). 100 H,O gave the following average values, the 
probable error in no case exceeding +'004, and being usually 
considerably less :— 
ie 
Zinc-Lead ......... 580 588 ‘591 
Lead-Copper ... "486 ‘501 519 
