Anyone made one of these?  I made one this afternoon and hooked it up to a 9v battery.  It made the ammonia bubble, but not much.  I used a steel rod and noticed afterward the sticker said it was coated.  It is silvery in appearance, but is not stainless steel.  Would this cause it not to work as well?

Also, how do you use a power supply from a cordless drill battery charger or computer printer for this?  I've heard of people using it but how do you do it?  How do you tell positive and negative?

Usually sleeve is (-) and the tip or inside part is (+).

hook up a volt meter and see if it says -X/volts if it does the positive terminal is on the black lead assuming the meter is hooked up with black to - and red to +

Quoted: Usually sleeve is (-) and the tip or inside part is (+).

you get an oddball everyonce in a while