372 Mr. J. J. Houd on the Laics of Chemical Change. 



A thorough investigation on this point might lead to many 

 interesting facts in science, and a clearer insight might be 

 gained into molecular action. 



For instance, by a comparison of the rates of change at 

 d iffe rent temperatures, all other conditions being the same, 

 the necessary data could be obtained to deduce the law of 

 temperature, and so find the point at which no action could 

 take place ; or, again, if analogous compounds, such as the 

 sulphates, nitrates, chlorides, &c, have an accelerating or re- 

 tarding effect on the change, their " equivalence " might be 

 determined or compared — that is to say, whether K 2 S0 4 , or 

 174 parts by weight of potassic sulphate, can perform the 

 same amount of work as Na 2 S0 4 , or 142 parts of sodic 

 sulphate. 



The cases of chemical change selected for investigation 

 would require to be under complete control, to allow of the 

 determination of the amount of change up to any period of 

 time, as it might so happen that the intervals of time between 

 two observations would require to be equal in order to calcu- 

 late the necessary constants required by theory. 



The methods of determining the remaining energy should 

 be accurate and speedy. 



When two bodies A and B undergo change and produce a 

 third, C, which does not take an active part in the change, it 

 will doubtless, by its mere presence, if not removed from the 

 sphere of action, either accelerate or more probably retard the 

 change taking place ; and if this effect be great, supposing C 

 not capable of being removed immediately it is formed, a 

 mathematical statement of the change would not be possible, 

 as the influence of C could not be determined. If, however, 

 the rate of change is so little influenced by the presence of C 

 that it may be neglected, a theory of the action can easil) be 

 formed as a guide to the experimentalist. 



The experiments detailed in this paper were made merely to 

 see how far the following theory of chemical energy is cor- 

 rect, neglecting all retarding or accelerating effects of the 

 compounds produced during the action. By an inspection of 

 the results, it will be evident that this influence cannot be 

 very large. 



Suppose two bodies in solution which are capable of react- 

 ing on each other to form new inactive compounds, and the 

 action taking place be expressed by an equation in terms of 

 the time and the amounts of remaining active bodies at that 

 time, on the hypothesis that the amount of change in an inde- 

 finitely small space of time is proportional to the product of 

 the remaining active bodies at that time. Let A and B be 



