Don't think hydrogen sulphide is the _only_ constituent of the smell though, as pure H2S smells like rotten eggs. So whoever posted saying this technique isn't that effective is probably right.
I was once asked by a chemistry teacher, 'why do farts smell ?'
Being a diligent student I looked up the chemical make-up of flatulence and found it to be mainly nitrogen, oxygen, carbon dioxide, hydrogen and methane - the latter 2 being flammable as any teenage boy with a lighter knows full well.
The smelly stuff is hydrogen sulphide but also indole, skatole and other sulphur containing compounds such as methyl mercaptan and methyl sulphide.
He was genuinely impressed but the answer to the question 'why do farts smell ?' was apparently 'for the benefit of deaf people'.
