280 



Mr Bevan, A Method of following the Course 



This method is applicable also in other cases where the action 

 is characterised by a change of conductivity in the medium of the 

 action. One such action is the inversion of cane sugar under the 

 catalytic action of hydrochloric acid. The amount of water present 

 here is affected by the combination of a molecule of water and 

 a molecule of the sugar, and the conductivity changes in con- 

 sequence. A change also may be produced by the alteration of 

 the sugar in the solution. But in any case the change of con- 

 ductivity affords a method of observing the change. In the 

 following experiment the resistance was measured by the Kohl- 

 rausch method with a telephone and alternating current. This 

 method is not so accurate as the commutator method, but it gives 

 results which are fairly satisfactory. The author is investigating 

 further some points in connection with this action with a view to 

 understanding this kind of catalytic action, and the experiment 

 here described is a preliminary one to find whether the action 

 could be thus investigated. The results are given in the following 

 table ; in the first column the time from the beginning of the 

 action and in the second the observed resistance. 



Inversion of Sugar. 



Time 



Resistance 



Time 



Resistance 



•13 



134-2 



91 



137-80 



•5 



133-2 



92 



137-74 



1-0 



133-9 



97 



137 87 



2-33 



134-0 



115-5 



138-13 



4-5 



134-0 



121 



138-00 



19-25 



135-3 



137-5 



138-06 



23-0 



135-3 



139-75 



138-19 



41 25 



136-33 



142-0 



138-25 



41-75 



136-52 



145-0 



138-21 



43-75 



136-60 



163-0 



138-27 



67-5 



137-30 



186-0 



138-36 



In Fig. 5 the curve 



y = (l _ e -*) 



is plotted. The change of conductivity corresponding to t— oo is 

 262. In the figure the changes of conductivity are divided by 

 262 and the times in hours by 10 - 45. The points are seen to lie 

 irregularly about the curve. 



