Influence of Heat on the Rate of Chemical Change. 



Malleable Cast-iron Ring, X (Soft) . 



Mean diameter =10-115 centim. 



Bar-thickness = 1*304 „ 



Number of coils = 1220. 



323 



33. 



[i obs. 



23. 



jjl obs. 



62 



178 



7144 



735 



276 



146 



7628 



724 



1293 



491 



7669 



755 



3784 



712 



8759 



715 



3976 



701 



9142 



626 



4395 



717 



9526 



618 



4622 



767 



10373 



495 



5045 



746 



11080 



417 



5247 



746 



11907 



276 



54i9 



753 



12412 



217 



5853 



754 



12876 



173 



6196 



759 



13562 



115 



6781 



762 



15762 



47 



XXXVI. On the Influence of Heat on the Rate of Chemical 

 Change. By John J. Hood, D.Sc. (Loncl.)*. 



TT1HE accelerating action of heat on the rate at which a 

 JL chemical change progresses has been made the subject 

 of investigation by several chemists. The amount of work 

 that has been done towards the elucidation of this side of the 

 great problem of chemical action, expressing the rate as a 

 function of the temperature, is as yet too insignificant to 

 allow of any deductions being drawn relative to the probable 

 mechanical processes that take place in a medium containing 

 a chemical system undergoing change. • Considered in the 

 light of molecular interdiffusion, it would seem probable that 

 the relation between the rate of change of different chemical 

 systems comprising two or more active bodies (active in a 

 chemical sense) and the temperature should be of the same 

 type; and the experiments that have been made on this subject 

 all seem to show this in common, that the rate of the change 

 increases very rapidly for small increments of temperature. 



Warder t, in his experiments on the speed of saponification 

 of ethylic acetate, was led to infer that the increase of speed 

 in this reaction is approximately as the second power of the 

 temperature. 



Mills and Mackey$ ? studying the evolution of hydrogen 

 from zinc and hydric sulphate at different temperatures, a 

 case of a chemical system of a non-homogeneous character, 



* Communicated by the Author. 



t American Chemical Journal, vol. iii. % Phil. Mag. [5] xvi. 



2A2 



