[NewCandle] Boric acid Redux

[Keith Nagel]

More boric acid fun....

I redid the experiment with the nickel cathode, a wire mesh basket
fastened with nickel wire. One of these days I'll get a spot
welder... Anyway, I was able to get the voltage up to 1300V
before breakdown, so it helped quite a bit to control the
E field around the anode in this fashion. 

Glow gets kinda bright around 1000V, although it remains the
case that when I switch to constant voltage and let the
cell sit current drops off to nothing and the glow extinguishes.
I think it is the case that the oxide is pretty insoluble
in this weak acid solution and so you only get the oxidation
reaction and a constantly increasing impedence. Quite different
from the stronger acids where the current would never really
diminish with DC.

I also tried ammonium borate, and found the limiting voltage
to be reduced by half, around 600V. The current was also greater,
I needed about 20ma before the voltage began to rise on constant
current. Did I get the crystalline layer? Hard to say, from visual
inspection it does look different but not that much. I suppose
I would know from a comparison of electrode capacity given two
electrodes anodized to the same voltage. One confusing aspect
of these experiments is that the cell temp changes as voltage
rises and power input increases. I have a peltier cooler, I
suppose it is time to put it to work. If I keep things cool
will I get a higher limiting voltage? 

K.