.\r.\CLEOD. — Udic of O.cidatioii of ActttihltJiiide to Aceiic. Arid . 43 

 The following experiment illustrates this : — 



Partial pressure of nitrogen = 30 mm. 



On the next day, using the same sample of oxygen, which had mean- 

 time remained undisturbed over the water, the action went on a little more 

 readily, though still much slower than formerly. 



Partial pressure of nitrogen = 22 mm. 



On shaking the water up to dissolve the chlorine, and allowing it to 

 stand several days, on again using it the action went on with very great 

 rapidity — ^greater, in fact, than that previously observed. 



Partial pressure of nitrogen = 24 mm. 



The speed of this reaction is somewhat remarkable. Nothing w^as 

 noticed to account for it. It may be that more water-vapour was present 

 than usual. These results show how susceptible the action is to disturb- 

 ing effects, the impurities in the oxygen being undoubtedly the cause of 

 the change in the velocity of the reaction in these cases. 



3. Vessel. — The speed with which the action proceeds seems also to be 

 influenced by the nature of the reaction-vessel. It has long been known 

 that the form and nature of the vessel has considerable effect on the velocity 

 of gaseous reaction, and this affords another marked example of it. Two 

 reaction-vessels were used, so as to enable an experiment to be made each 



