484 
Messrs. Smith and Moss on the Contact 
The chief results of the measurements are summarized in 
the following Table : — 
1. 
2. 
X 
4. 
5. 
<;. 
7. 
Strengths 
of 
solutions. 
Max. S.T. 
KCN 
(scale- 
reading). 
Max. S.T. 
KCl 
(scale- 
reading). 
E.M.F.of 
Max. S.T. 
KCN 
volt. 
Horizontal 
distance 
between 
curves. 
volt. 
KCN KCl + 
volt. 
! KCN + 
volt. 
JKCNjKClU 
YOlt. 
o-i ». 
36-65 
36-75 
■039 
•645 
•642 
•043 
•679 
•2n. 
36-30 
36-70 
•020 
•667 
•671 
•018 
•694 
•24 n. 
36-10 
36-: 3 
010 
•687 
•687 
•012 
698 
•25 n. 
36-08 
36-35 

•691 
•690 
•003 
•699 
•26 ii. 
36-04 
36-30 

•696 
•693 
-•001 
•697 
•27 n. 
3600 
. 36-27 
-•005 
•697 
•696 
-005 
•693 
•50 n. 
35-81 
36-17 
-•020 
•716 
•715 
-016 
•703 
1-0 n. 
35-70 
36-10 --059 
•748 
•745 
-•046 
•705 
Solutions of KCN and KCl o£ equal strength being of 
approximately the same conductivity and degree of ionization 
(cf. Kohlrausch & Holborn, Leitvermogen der Elektrolyte, 
pp. 145 & 148), the contact potential-difference between 
them will be very small, probably less than a millivolt. 
This is confirmed by the agreement between the numbers in 
Columns 4 and 5, since the former represents the difference 
between Hg | KCl and Hg | KCN (cf. Phil. Trans. I c. 
pp. 69 et seg.). 
Each number in Column 7 should be equal to the sum of 
the corresponding numbers in Columns 5 and 6. A com- 
parison serves to indicate the limits of the uncertainty of the 
dropping-electrode measurements. The jet fell freely in 
contact with the air. By comparison of the numbers in 
Columns 3 and 6 it will be seen that Pascheir's relation held, 
within the limits of errors of experiment, in every case. 
The null solution was that for which the surface-tension 
was a maximum in the natural state (applied E.M.F. zero). 
Its strength was, in round numbers, w/4 KCN, and assuming 
with Palmaer that, in consequence, Hg ' n/4 KCN = 0, it 
would give, by Column 5, Hg | ra/4 KCl = 0*6 9 approxi- 
mately. 
§ 10. As will be seen later, a solution of ?*/4 KCl, ex- 
amined according to either of the methods described by 
Palmaer, would have given a null solution from which he 
would have deduced the value Hg I w/4 KCl = 0*565 approx. 
