Messrs Jones and Richardson, On Hydrogen Ions. 
337 
Note on a Method for determining the Concentration of Hydrogen 
Ions in Solution. By H. O. Jones, B.A., Clare College, and O. W. 
Richardson, B.A., Coutts Trotter Student, Trinity College. 
\Read 3 February 1902.] 
The following investigation was suggested by a series of obser- 
vations by Mr Fenton and one of the authors 1 . They showed that 
oxalacetic hydrazone decomposed in presence of water at 100°C. 
into carbon dioxide and pyruvic hydrazone. In the presence of 
strong acids, however, the reaction proceeded differently and 
pyrazolone carboxylic acid and water were formed. With weak 
acids or very dilute strong acids the two reactions occurred simul- 
taneously and it was shown that the amounts of carbon dioxide 
given off, using acids of the same normality, were in the inverse 
order of their “ affinity constants.” 
It was suggested that these reactions might be explained by 
supposing that the formation of pyruvic hydrazone was due to the 
decomposition of the negative ion according to the following 
equation : 
— + 
COOH . C . CH 2 . C0 2 + H = C0 2 + COOH . C - CH 3 (1) 
II II 
N.NH.C 6 H 5 N.NH.C 6 H 5 ; 
whereas the undissociated molecule decomposed as follows : 
CH.-CO.OH CH 2 -CO 
I -H | | 
C:N.N.C,H, = C:N.N.C,H, + H 1 0. (2) 
I I 
C0 2 H COJ1 
The effect of acids would thus be to diminish the concentration of 
the negative ion and hence to reduce the amount of carbon 
dioxide produced. 
The experiments here described were undertaken with the 
view of further developing this hypothesis, and of testing its 
quantitative validity. The theoretical problem is one of some 
complexity, since it is necessary to take into account the simul- 
taneous occurrence of two reactions, the products of each of which 
exert an effect on the rate at which the other proceeds. In the 
case where the concentration of the hydrogen ions due to the 
hydrazone is negligible compared with that due to the acid used, 
1 Fenton and Jones, Jour. Chnn. Soc. 1901, lxxix. p. 91 ; Proc. Ghem. Soc. 1901, 
p. 24 ; Proc. Canib. Phil. Soc. xi. 2, p. 108. 
