I learned about this at a soapmaking forum I belong to.
I've been using it for about six months, and I love it--no more itchy underarms. It isn't quite as strong as regular deodorant, but works pretty well--although I'm not a terribly smelly person, I'd say average.
I use sodium bicarbonate, it is not the same but in principe it is a natural simple way to deodorise. On me it works very well.
Just put a little powder on the tip of your finger, wet your underarms a bit and spread the bicarbonate that will dissolve with the little water.
Or you can make a saturated water with bicarbonate and spray it as a normal deodorant.
the deodorant thing sounds awesome, i love using milk of magnesia as a mattifying liquid (keeps ultra oily skin matte longer than anything else, but messy and if you even slightly taste it beside your lips, yuck). I will try my Phillips tomorow as deodorant and report back (I do have quite a fair amount of hydrosis so I should be a good gauge).