While waiting for magicsound's results, I wanted to make another test. Unfortunately one of the zip ties I used to hold the electrodes together broke and a quick fix I attempted didn't restore the electrodes to the previous tight fit. The electrode gap got significantly wider than usual and probably mainly because of this I haven't been able to reproduce the hissing noise as in the past few tests.
Right now I'm struggling with OCR'ing current data from the current clamp, which doesn't have a very readable display.
I tried to measure voltage directly across the electrodes, and kind of expecting high voltage spikes below 1000V or so I made a voltage divider to avoid damaging the multimeter. 2 MOhm on across both ends and 0.4 MOhm across the last resistor, for a 5x voltage reduction. Unfortunately I didn't manage to observe any spike justifying its usage, but that's also probably because the reaction didn't proceed as usual.
Since I used the 200V scale on the multimeter with the measured values divided by 5 this also means that measurements for the low voltages observed haven't been very precise.
The syringe was used for periodically introducing distilled water as the solution got evaporated or electrolyzed, but I forgot to weight the jar before and after the test. The water level was gauged by eye, so this was not a very accurate test either. While the total amount of water introduced in the end could give some indications about the heat produced, since electric measurements are quite rough this will probably not be as useful as initially expected.
I will post some graphs when the OCR process has finished, but this time I'm not trusting my own data very much.