"The only substance that will give anywhere close to the effect that you need is Kolokol-1, an incapacitating gas that my father helped develop many years ago. It is delivered as an aerosol, and takes one to three seconds to cause unconsciousness, which can last anywhere from two to six hours. I have no idea what effect it would have on the goblin nervous system, however. The risk in humans is that it causes a degree of hypoventilation – respiratory depression – which can lead to apnoea – a, ah, cessation of breathing, eh?" Maddy added for the benefit of the wizards and witches, who mostly had no idea what apnoea was. "Nausée is also common, which can cause the subjects to drown in their own vomit while they lie unconscious. Fatalities are probable, but they would still be less than would occur with traditionnel wizarding tactics."