40 



T ran.^actiouH. 



Experiments made to determine whether such a Maximum Pressure 

 AS that indicated by Dr. Ewan's Experiments did exist. 



In this connection the chief points to be cleared up were : (1) Whether 

 a maximum reaction pressure did exist ; (2) whether the pressure of alde- 

 hyde had any effect on it ; (3) the effect of temperature on this maximum 

 pressure, if it was found to exist. 



At the outset it may be said that although the rate of reaction, as. 

 indicated by the value of K', seemed to diminish with higher pressures of 

 oxygen, the pressure of aldehyde remaining constant, yet there was nothing 

 to show that the action came suddenly to an end, as is indicated by Dr. 

 Ewan's experiments. Further, as will be shown later, on raising the percent- 

 age pressure of aldehyde the value of K' again rose, even though the oxygen- 

 pressure remained high. Some explanation from theoretical considerations, 

 as will be shown later, can also be given of the fact that the value of K' is 

 small when there is a big pressure of oxygen and a small one of aldehyde. 



It will be as well at this stage to quote some experiments to illustrate 

 this point. 



Except where otherwise stated, the oxygen, prepared from j)otassium- 

 chlorate and manganese - dioxide, was . dried over calcium - chloride. No' 

 attempt was made to absorb the acetic acid formed. 



Partial pressure of nitrogen 

 Partial pressure of acetic acid 



20 mm. 

 12 mm. 



Partial pressure of nitrogen 

 Partial pressure of acetic acid 



27 mm. 

 12 mm. 



Partial pressure of nitrogen = 23 mm. 

 Partial pressure of acetic acid = 12 mm. 



