324 Dr. J. J. Hood on the Influence of Heat 



found a relation between what they call the " zero strength " 

 and the temperature, represented by the equation 



, b + ct 

 d+t 



Urech *, from experiments on the speed of inversion of cane- 

 eugar by acids at different temperatures, expresses the rate as 

 a function of the temperature of the form at + u f t 2 + a, f/ t?. 



More recently Menschutkin | has studied this subject, em- 

 ploying the rates of formation of ethylic acetate, acetanilide, 

 and acetamide. His results show that if e and e' represent 

 the amounts of these bodies that are formed during the interval 

 of one hour at temperatures 6° and #° + n°, the value of € / — e 

 passes through a maximum at a definite temperature. 



LemoineJ, with reference to the simplest case of a chemical 

 change represented by the equation 



jf-AG.-,), 



such, for instance, as the action of hydric peroxide on a soluble 

 iodide in presence of sodic thiosulphate, as worked out by 

 Harcourt and Esson, says: — " Un fait tres general et tres 

 digne de remarque est l'extreme accroissement du coefficient 

 A, c'est-a-dire de la vitesse de decomposition avec la tempe- 

 rature. Si 6 est la temperature, A parait varier avec elle 

 suivant une formule exponentielle A = a f a . Ce fait, resultat 

 d'une multitude d'experiences, parait correlatif de la nature 

 meme de ce mouvement interieur qui constitue la temperature 

 d'un corps." 



The " multitude d'experiences," however, would seem to 

 imply the common observation of the great increase in rapidity 

 of a chemical reaction with small increase of temperature. 



In a paper published in this Journal §, in which the oxida- 

 tion of ferrous sulphate by potassic chlorate was the subject 

 of investigation, it w r as shown that the course of the oxidation 

 was represented by the equation 



g— tfW • (i) 



Integrating and writing it in the form y(a 4 i) = b, it is clear 

 that for two experiments made at different temperatures 6* 



and 0° + n°, the relation % = ^tt^ holds. 



b A 6 ) 



* Berichte d. d. Chem. Gesell. xvi. p. 762. 

 t Journ, Prald, Ch. 1884. 



X " Etudes sur les Equilibres chimiques," p. 178 (Fremy's Ency. Chtm.). 

 § Phil. Mag. [5] vi. 



