TEMPERATURE OF THE RATE OF A CHEMICAL CHANGE. 
203 
It is possible that this mode of measuring the effect of one phenomenou upon 
another may have a wider application. In studying the relation between unemploy¬ 
ment and pauperism, the proper course might be to take the ratio of the increase per 
cent, of pauperism to the increase per cent, of unemployment as the measure of the 
effect of one upon the other. The ratio of the increase per cent, of coal or oil 
consumed in a ship to the increase per cent, in the number of knots attained by the 
vessel might be used with advantage in comparing the merits of coal and oil. 
{-June 15.—The I’eferees of this paper have asked the author to discuss, with 
reference to the law here advocated, the experiments of Teautz and Volkmaxx “ On 
the Saponification of Esters,” ‘ Zeit. Ph 3 "s. Chem.,’ 1908, 64, pp. 53-88; 1909, 66, 
p. 496 ; 67, p. 93 ; 68, p. 295.'-= 
Teautz calls the ratio n = the temperature coefficient of the rate of 
chemical change; and he discusses the effect of temperature on the value of n, which 
is a constant when the rate increases in geometrical progression as the temperature 
increases in arithmetical progression. This relation has been often used since its first 
use by Beethelot in 1862. In most experiments n has been found to decrease with 
temperature, but in the cases of saponification of esters it first increases and then 
decreases, having a maximum value between 10° C. and 20° C. Teautz connects 
this with a similar maximum of viscosity in the medium in which the chemical action 
is taking place. 
The value of m = (7’“^ dI-)/(T“^ dT) also shows a maxunum value at the same point. 
The following table exhibits the values of m and n in the experiments with methyl 
acetate, vol. 64, p. 83 :— 
t. 
m. 
n. 
m = 20 
n 
0 
10 
1 17-9 
1 ■ 85 
2-05 
20 
i 23-5 
2-26 
2-00 
30 
! 19-0 
1-87 
1-96 
40 
18-2 
1-81 
1-91 
50 
17-7 
1-75 
1-87 
[* It appears from the results of several experimentalists that the saponification of esters at different 
temperatures does not give, for the change of rate with temperature, interpretable results. This may be 
owing to a complication in the reaction or a liability to error in the subsequent analysis. Volkmaxx 
does not describe his modus operandi fully enough for any judgment to be formed. Nor does he interpret 
his results. See p. 88. 
Both he and Teautz, who is the sole author of the three subsequent papers in vols. 66, 67, and 68 of 
the ‘ Zeitschrift fiir Phys. Chem.’ (in which there is no experimental work), give lists of the literatitre of 
the subject which do not include Esson’s and my jJapers. Our formula is given, vol. 64, p. 57, but is not 
referred to elsewhere or discussed. Nothing in Volkmann and Trautz’s papers leads me to doubt of 
anything we have written.—A. V. H.] 
2 D 2 
