Thanks for that. I suspect that one should view the Noxzema as the guilty party here!
The soap has the following ingredients according to what i can find.
potassium stearate, sodium stearate, potassium tallowate,aqua, lac powder, parfum, sheep milk, arachis hypoaea, lanolin, potassium cocoate, sodium tallowate, sodium cocoate, glycerine, potassium hydroxide, sodium hydroxide, alpha-isomethyl ionone, hydroxisohexyl 3-cyclo-hexene carboxaldehyd, CI 77891
The only recognised 'baddy' I can see here is alpha-isomethyl ionone, which is 'powdery' scent but is now banned from fragrances although it can be used in soap etc. The rest would be a fairly normal soap. There is no Tetrasodium Etidronate on my ingredients list - strange.
I suspect we are seeing a reaction between sodium/potassium salts and the ammonium hydroxide to form sodium/potassium hydroxide + ammonia.
Bottom line is that Noxzema + this soap (and maybe others) is NOT a recommended combination!