In article , Clifton T. Sharp Jr. wrote:

I suspect the internal resistance of the battery limits what can flow
through your nice, wet tongue. I don't remember the short-circuit current
of a typical 9V battery, but it seems to me the last time I tested one
it was in the tens of milliamps.

Seems to me wet tongues have more resistance than fresh 9V batteries.
At least alkaline ones. I can usually light up a 93 bulb with one, and
that takes nearly an amp. Sometimes a 9V battery can light up an 1156
bulb, and that requires well over an amp.

- Don Klipstein )