APPENDIX 339 



tions rapidly and note the time which elapses until the blue color 

 sets in. 



The experiment is now to be repeated; but I take solutions which 

 have been warmed in order that the molecules may move more 

 rapidly. The relative quantities of the total volume remain the 

 same. You note how much more rapidly the molecular exchange has 

 taken place. 



In order now to show you that space has something to do with 

 this reaction, I must increase the distances between the molecules in 

 order that they shall be obliged to traverse more than the previous 

 distance in order that they may meet one another. How can I do 

 this ? Simply by distributing them evenly over a larger amount 

 of water. You will remember that I had employed 25 cc. of each 

 acid solution, 5 cc. of starch paste and 20 cc. of water, or 75 cc. 

 in all. If I now preserve all of these measures, excepting that I 

 substitute 95 cc. of water for the 20, the total bulk will be 150 

 cc., while the molecules of reacting acids will remain the same. In 

 this case, then, the speed is very much diminished, although the 

 time required is not exactly doubled, for there are so many other 

 questions entering in here, the reaction is complicated. 



In order to produce still another effect, I shall maintain the quan- 

 tities of this last experiment, but raise the temperature. The time 

 now approximates that of the first experiment. 



Yet another variation may be easily made; I shall increase the 

 amount of iodic acid while maintaining the amount of sulphurous 

 acid, and I shall again so arrange that the total volume is 75 cc. 

 A little explanation is here necessary, inasmuch as I shall take 

 only 25 cc. of iodic acid solution, but this is made of just double 

 the strength of the one I originally used. In this case, again, you 

 will see the speed of reaction is augmented and the time very much 

 reduced. 



The results that I have shown you here involve energy, space, and 

 time, as well as matter, and I have varied the energy by changing 

 the temperature, and the space by changing the volume, and you 

 have seen how time was affected. 



