[Bored chemist]

It wasn't me who wrote that.

Sorry for the confusion.
As you say, the quote function sometimes makes a mess of attribution.

[Mitko Gorgiev]

I consider this as yet another great evidence that the electric current flows de facto from the Plus to the Minus-pole of the battery.

It doesn't indicate anything like that.

What does it indicate according to you?

[alancalverd]

The spark experiment is indeed counterintuitive, and contrary to what happens in vacuo. We use field emission of electrons from a sharp spike, in several applications such as cold-cathode x-ray tubes and electron microscopes, and the source electrode is always negative.