Usage of AC to measure the conductivity of ionic solutions

there was this statement in my [chemistry textbook](https://ncert.nic.in/ncerts/l/lech103.pdf)....



> 
> However, for measuring the resistance
> of an ionic solution we face two problems. Firstly, passing direct current
> (DC) changes the composition of the solution. Secondly, a solution cannot
> be connected to the bridge like a metallic wire or another solid conductor.
> The first difficulty is resolved by using an alternating current (AC) source
> of power<
> 
> 
> 


I don't understand how using AC over Dc would help, I mean electric current would pass ( although less than it would have otherwise) but still it could change the composition of a solution by electrolyzing it. So why AC?




* Since AC can be *capacitively* coupled to the solution, metallic electrodes don't need to contact the solution -- they can be **outside** an insulating container, e.g., glass or PTFE, avoiding introducing metal ions.
* At moderate AC frequencies, ions won't migrate an appreciable distance in one direction before returning to that position on the opposite half of the cycle. Steam vaporizers running at 50 or 60 Hz, using electrodes immersed in salt water, do not produce hydrogen and chlorine, just hot water and steam, for example.


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